WELCOME physicsphysicsworld.com worldVolume 34 No 3 March 2021 Physics World – free sample issue Welcome to your complimentary copy of the March 2021 issue of Physics World magazine.

For more than 30 years, Physics World has been helping physicists around the world stay up to date with the latest developments in the subject. Including in-depth Pots of potential features from acclaimed physicists and science writers, comprehensive news and Archaeology sheds light on our magnetic past analysis, and incisive opinion pieces, careers articles and book reviews, each edition has lots for you to enjoy.

The cover feature of this free sample issue examines how geophysicists are using archaeological artefacts to piece together how the Earth’s magnetic field has changed in the past – and how it could vary in the future (p37).

There’s a great feature about how research at the intersection between physics and biology is leading to new generation of topological soft materials based on DNA (p48). Don’t miss either our look at the rising stars in cosmology who are re-examining what Einstein called his “biggest blunder” (p42).

You can also find out about the UAE’s Hope mission to Mars (p12), the Chinese underground detector hinting at dark matter (p5), the importance of teaching children about careers in physics (p23) – and more besides.

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Matin Durrani Editor-in-chief, Physics World

Make or break Building topological soft materials with DNA Heavenly challenge New ideas on the cosmological constant Career questions Making children feel positive about science

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com Contents: March 2021

simulation case study Looking beyond our solar system with ray tracing

Open science Comfortable burden? Greener future simulation... Introducing young children to science careers 25 New theories about the cosmological constant 42–46 Troels Schönfeldt’s career path to nuclear 61–62

Astronomers detected an Earth-like planet 11 light-years away Quanta 3 from our solar system. How? Through data from an échelle Features spectrograph called HARPS, which finds exoplanets by detecting Frontiers 5 tiny wobbles in the motion of stars. Engineers looking to Chinese detector supports hints of dark matter ● Properties of Digging up magnetic clues 37 further the search for Earth-mass exoplanets can use ray tracing einsteinium revealed ● “Alpha clusters” seen on neutron-rich We’ve known for centuries that a record of the Earth’s magnetic ● ● past might be stored in objects made from fired clay. Rachel Brazil simulation to improve the sensitivity of échelle spectrographs. nuclei Click beetle’s jump revealed Egg yolk sheds light on brain injury ● “Sextuply” eclipsing star system spotted explains how geophysicists are now using that concept to get clues about the future course of our planetary field learn more comsol.blog/echelle-spectrographs News & Analysis 12 UAE Mars orbiter becomes first craft from Arab country to reach A new generation takes on the another planet ● Planetary probes could study gravitational waves cosmological constant 42 ● China mission releases first Mars image ● “Dismay” at state of Rob Lea reveals how several rising stars in cosmology are tackling geoscience education ● France unveils €1.8bn quantum plan what Albert Einstein once called “his biggest blunder”. But will their ● Support for arrested US scientist with China links revolutionary theories be accepted? ● Concerns over renaming of Oxford chair Make or break: building soft materials Comment 21 with DNA 48 Entangled thoughts DNA molecules are constantly getting broken up and glued back together to adopt new shapes. Davide Michieletto explains how Forum 23 this could lead to new kinds of “topologically active” materials Supporting science in difficult times Caitlin Duffy ● Widening career aspirations Carol Davenport Reviews 55 The superheavy element hunt Hamish Johnston ● Strolling in Transactions 27 the deep Ian Randall Grounds for optimism James McKenzie Careers 61 Critical Point 29 Rethinking nuclear for a greener planet Julianna Photopoulos Beneath the rotunda Robert P Crease Recruitment 63 Feedback 31 Your thoughts on making physics inclusive, school teaching, Lateral Thoughts 68 long-term thinking and free will Fine structure and black holes Sidney Perkowitz

On the cover Physics World is published monthly as 12 issues Archaeology sheds light on our per annual volume by IOP Publishing Ltd, Temple Circus, Temple Way, Bristol BS1 6HG, UK Multimedia magnetic past 37–41 (Mat Ward/IOP Publishing) United States Postal Identification Statement Listen to the latest Physics World Building topological soft materials Physics World (ISSN 0953-8585) is published with DNA 48–52 monthly by IOP Publishing Ltd and distributed in NASA/JPL-Caltech Stories podcast to hear about the the USA by UKP Worldwide, 3390 Rand Road, New ideas on the cosmological South Plainfield, NJ 07080. Periodicals postage search for past life on Mars with NASA’s constant 42–46 paid at Rahway, NJ and at additional mailing Perseverance rover (bit.ly/3puCT04) The COMSOL Multiphysics® software is used for simulating designs, devices Making children feel positive about offices. US Postmaster: send address changes science 25 to Physics World, IOP Publishing, C/O 3390 and processes in all fields of engineering, manufacturing and scientific research. Rand Road, South Plainf ield, NJ 07080.

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Lock-in Amplifiers For the record Seen and heard The return on such an investment 37 m isn’t that bad given that Shepard is high wasn’t wearing natty golfing trousers and … and more, from DC to 600 MHz Cherry Murray from the University of Arizona a short-sleeved polo shirt. Instead, he

writing for APS Physics London Barrett had to hit his balls wearing a tight-fitting Murray – a former president of the American spacesuit and swinging his club with one Physical Society – says that governments will arm. “I would challenge any club golfer seek to stimulate the economy following to go to their local course and try to COVID-19, which could be a boon for physics hit a six-iron, one-handed, with a one- research. quarter swing out of an unraked bunker,” Saunders told the BBC. Maybe lunar It was actually rather gratifying to see sports fans will have to stick to a round of how many people are interested crazy golf. Physicist Gordon Watts from the University of The case of the cubic poo Washington quoted in Symmetry Lunar living If there’s one mystery that has longed Some 1500 ideas or “letters of interest” have The housing market might be a bit puzzled biologists, it’s why wombat poo been submitted to the US Snowmass exercise, sluggish with lockdown in full swing, but is not round but shaped like a cube? The which helps to plan the future of particle physics. that hasn’t stopped housing developer thinking used to be that cubic faeces are Barratt London teaming up with the formed during the act of defecation, with It’s like the Academy Awards British Interplanetary Society to create a the wombats producing this shape to stop Joseph Lykken, Fermilab’s chief research officer, prototype home for future astronauts on the poo from rolling away, thereby helping quoted in Science the Moon. Consisting of two floors with the animals to communicate (see January a 2 m-thick roof to protect inhabitants 2019 p5). Now, however, physicist David The Muon g-2 experiment at Fermi National from radiation, the lunar module boasts Hu from Georgia Institute of Technology, Accelerator Laboratory is expected to report a three bedrooms that are on the lower along with colleagues in the US and new measurement of the magnetism of the muon floor to further reduce the radiation dose. Australia, has discovered that wombat this month. The open-plan upper floor, meanwhile, poo is cube-shaped thanks to the muscles features a kitchen, dining and living that line the marsupial’s intestines. They She wrote back to him, ‘Write me a space as well as a gallery that offers do not have cylindrical symmetry but paper on quantum physics and I’ll the “perfect place” to view the lunar rather create two stiff and two flexible do it.’ landscape and, “if you’re lucky”, catch regions, which means that as the material Earth in the distance. Barratt says that moves through the intestines, rhythmical Kevin Bright, executive producer of the US hit TV many amenities in the terraced properties muscle contractions sculpt the poo into show Friends, quoted by Hollywood Reporter starting at will be available such as electricity, water, cubes. The team says its discovery could Bright was commenting on how Matthew Perry Internet and – thankfully – air. The house “have applications in manufacturing, Optimized detection for pulsed $6,600 (who played Chandler) once managed to would be built using resources found on clinical pathology and digestive health”. convince Julia Roberts to guest star on the show. the Moon including basalt bricks, but And where was the research published? measurements: Boxcar averager furnishing it will be “one of the trickiest Soft Matter (17 475), of course. The types of stitches, the differences aspects of living on the Moon” as wood Simplified image acquisition for laser scanning and plastic would have to be flown in from Stamp of success in their geometries as well as the USPS microscopy: Image recorder Earth. Connecting each property is also The US Postal Service has order may determine [the fabric’s] a “street”, which to us looks more like an issued a commemorative One-box solution for laser locking properties underground bunker despite the smiley, stamp honouring the Physicist Elisabetta Matsumoto from the happy people on the company’s CGI Chinese-American and stabilization: PID/PLL Georgia Institute of Technology quoted in mock-up. Perhaps it should be renamed physicist Chien-Shiung Science News The Crescent? Wu. The 1957 Nobel Prize Seamless control with your choice of API: Matsumoto has combined knitting and for Physics was shared A load of Moon balls by Chen Ning Yang and Python, C, MATLAB®, LabVIEW™ and .NET mathematics and is now training a computer to think like a knitter. If we did eventually ever settle on the Tsung-Dao Lee “for their penetrating Moon, we’d need something to while investigation of the so-called parity laws away those long dark nights…so how which has led to important discoveries The results of this study may have about a spot of golf? Alan Shepard, of regarding the elementary particles”. wider application course, famously hit a couple of golf balls However, some physicists argue that Wu Alexander Fedorchenko from the Czech during the Apollo 14 mission in 1971. should have shared the prize for providing Academy of Sciences quoted in the Daily Mail Despite shanking his first attempt with a the experimental evidence for Lee and Fedorchenko and colleagues has been studying makeshift 6-iron, he claimed his second Yang’s theoretical prediction of parity the physics of frying pans, finding that when the shot went “miles and miles and miles”. violation. Wu now follows in the footsteps Zurich Find out more today oil disperses outwards, it leaves dry spots in the Imaging specialist Andy Saunders from of Albert Einstein, Enrico Fermi, Richard centre to which the food can stick. the UK has now put Shepard’s boast to Feynman and Maria Goeppert Mayer www.zhinst.com the test, but found that the ball travelled with a commemorative stamp. Just a Instruments barely 37 m. Still, as Saunders point out, shame it was never a Nobel too.

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 DESKTOP SOLUTIONS CAEN Electronic Instrumentation physicsworld.com Frontiers A whole lab on your desk! China detector hints at new physics The PandaX-II dark-matter experiment has confirmed previous signs of exotic particles but further evidence will be needed, as Edwin Cartlidge reports

New data from the PandaX-II par- three years apart, they say they were ticle detector in China leave open able to measure the energy spectrum the possibility that the XENON1T of the tritium contamination within experiment in Italy has found evi- the experiment. By subtracting the dence of new physics. Researchers background spectra of tritium, kryp-

working on XENON1T had last year PandaX Collaboration ton and radon, the researchers were announced the detection of around able to quantify any signals from 50 events above background levels putative solar axions or a high neu- and concluded that hypothetical trino magnetic moment. Liu’s team Logic units Digitizers & MCA High Voltage solar axions or very magnetic neutri- found that the remaining electron nos might be responsible. The new recoils were in fact consistent with results from PandaX-II are consist- the excess events seen by XENON1T. ent with these hypotheses but fur- However, the researchers could not ther work will be needed to settle the fully endorse the earlier result given, issue (Chinese Phys. Lett. 38 011301). they say, that their data were also XENON1T was built to hunt consistent with a “background-only for a type of dark matter known as Closing in dwarf stars dimmer than they appear. hypothesis”. weakly interacting massive particles The PandaX-II However, as Aprile and colleagues The researchers in China are now (WIMPs). Housed under a mountain detector has point out, the events could also have increasing their detector mass to at Italy’s Gran Sasso National Labo- undertaken a careful had a more mundane explanation – 6 tonnes – meaning a sensitive target ratory, it contained 3.5 tonnes of analysis of the beta decay of tritium nuclei. This of 4 tonnes – while lowering back- liquid xenon and operated between background events would come about when the few neu- ground rates. Dubbed PandaX-4T 2016 and 2018. Like other experi- that could account trons liberated from surrounding it should start taking data this year. ments of its type, it was designed to for signals seen in rock by cosmic rays create tritium by Also coming online are an upgraded pick up the tiny flashes of light gener- other experiments. splitting xenon nuclei. Unlike other 8.3 tonne “XENONnT” as well as SiPM and array detector readout ated when WIMPs in the “halo” of background processes, this remains the 10 tonne LUX-ZEPLIN detector Preamplifiers Signal Generators dark matter thought to envelop the a nuisance since its extent is not pos- currently being installed in the San- Milky Way collide with xenon nuclei. sible to estimate reliably. Aprile and ford Underground Research Facil- The events reported in 2020, how- colleagues calculate that the tritium ity in South Dakota, US. “A year of ever, involved electron, rather than theory could account for the excess low background data taking from nuclear, recoils. Elena Aprile of events with a statistical significance PandaX-4T would be able to offer a Handy units to easily power and read out any detector Columbia University in the US and of 3.2σ – compared to 3.4σ, 3.2σ definitive answer to the XENON1T CAEN provides a wide range of Desktop modules to easily build your laboratory experiment. CHECK THIS OUT! colleagues reported 53 ± 15 such and 3.0σ for solar axions, neutrino excess,” Liu says. recoils at low energy that they could magnetism and bosonic dark matter, Yet Matthew Szydagis, Cecilia With just few red instruments on the desk you will be able to bias your detectors, digitize not tie to other identifiable sources respectively. Levy and colleagues at the State of background (these events them- Jianglai Liu of Shanghai Jiao Tong University of New York at Albany and read out multiple signals or program your logic operations. selves being considered noise in the University and colleagues have now already have an explanation for the search for WIMPs). carried out an independent experi- XENON1T excess – and it does not You can even generate detector-like signals to test and validate acquisition systems or Careful not to claim any discovery, mental check on the XENON1T rely on exotic new physics. They experiments prototypes. they instead laid out several possible results using the PandaX-II detector modelled background interactions explanations for the observation– in the China Jinping Underground within the Gran Sasso detector and including the possibility it was caused Laboratory in Sichuan. Although found that around 30 decays of the by hypothetical particles known as PandaX-II contains barely over half isotope argon-37 would generate the axions from the Sun or solar neutri- a tonne of xenon, the researchers observed excess. Levy says that their nos with a greater magnetic moment ran their experiment for longer and hypothesis could be investigated by than previously observed. Another acquired nearly half as much data thoroughly calibrating the XENON possibility, they said, was “bos- as their XENON1T counterparts. detector, adding that her group onic dark matter”, which would be The Chinese group also character- does not know where the argon absorbed, rather than scattered, by ized their background spectra bet- might come from. But the observed the xenon nuclei and cause electrons ter, thanks to direct measurement excess should be scrutinized by the CoMPASS WAVE to be emitted. Theorists then put for- or calibration. In part, this was done larger experiments. “If it is due to a C A DDE E new particle, it should predictably N GECO DUMP ward several ways to overcome one by twice injecting methane with one 2 030 CAEN CAEN CAEN obvious sticking point with the Sun- of its hydrogen atoms replaced by scale with the more massive detec- based hypotheses – that the flux of the tritium into the target. tors,” she says, “and a signal should particles involved would make white With the two injections carried out be clear.”

Free and easy-to-use software always included! Small details… Great differences Physics World March 2021 5

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 edwardsvacuum.com physicsworld.com Frontiers Turbomolecular Pumping Stations Nuclear physics lography studies. Delays related The Edwards Turbomolecular Pumping Stations are a comprehensive range of to the COVID-19 pandemic also meant that they were losing their products providing versatile vacuum solutions in many different applications. sample due to radioactive decay. To All our nEXT turbomolecular pumping stations are supplied fully assembled Mysteries of einsteinium unveiled overcome these problems, the team bonded the einsteinium atoms to and ready to run straight out of the box with both nEXT turbomolecular New insights into the physical and groups of organic molecules called pumps and backing pumps that are end user serviceable. chemical properties of the rare heavy ligands, which acted as lumines- element einsteinium have been cent antenna and then analysed the gained by researchers working at sample using X-ray absorption spec- Find out more on www.edwardsvacuum.com several labs across the US. The team, troscopy, carried out at the Stanford led by chemist Rebecca Abergel at Synchrotron Radiation Lightsource. Lawrence Berkeley National Labo- By measuring the resulting spec-

ratory, claims the results shed light Sargent/BerkeleyMarilynLab trum of the sample, Abergel and on the poorly understood proper- colleagues determined the bond dis- ties of the heaviest elements and tance of einsteinium, which is crucial could help scientists synthesize new in understanding how metallic atoms and even heavier elements (Nature bind to molecules. In addition, they 590 85). uncovered aspects of einsteinium’s The periodic table displays the physical chemistry that deviate from elements in a systematic way that expected trends across the actinide provides insights into their chemi- series. This knowledge could open cal properties. However, this order 99 not out In their study, Abergel and team new avenues of research into how breaks down for the heaviest ele- Leticia Arnedo- studied einsteinium-254, which is actinides could be used in areas ments, which can behave in unex- Sanchez (from left), the most stable form of the element, including nuclear power, and novel pected ways given their positions in Katherine Shield, with a half-life of 276 days. They did pharmaceutical drugs. the table. Understanding the chem- Korey Carter, Jennifer this by making a 250 × 10 –9 g sample The discoveries also improve our istry of these elements is difficult Wacker and using the High Flux Isotope Reactor understanding of how physics and because they can only be synthesized colleagues have at Oak Ridge National Laboratory chemistry is altered towards the in minute quantities and have short determined the bond in Tennessee by bombarding curium edge of the periodic table. This could half-lives. distance of targets with neutrons to trigger spe- enable researchers to better predict With an atomic number of 99, einsteinium, which cific radioactive decay chains. the processes that occur when ein- einsteinium is a metal and is in the was first discovered Unfortunately, the research- steinium and its actinide neighbours same actinide row of the periodic in 1952. ers encountered several setbacks, are bombarded with other atomic table as uranium. It is also the heavi- including discovering californium nuclei in the hopes of creating even T-Station 85 est element that can be produced in (element 98) contaminants in their heavier elements that have yet to be quantities large enough to carry out sample, which meant that they could discovered. “classical” chemistry experiments. not perform planned X-ray crystal- Sam Jarman ‘Alpha clusters’ discovered on neutron-rich nuclei

“Alpha clusters” resembling helium-4 Alpha spotter of a nucleus to become free particles nuclei have been spotted on the Researchers used – explaining a common radioactive neutron-rich surfaces of heavy atomic the Grand Raiden process called alpha decay. While alpha nuclei. An international team of spectrometer at decay is a much-studied effect, it has physicists, led by Junki Tanaka at Osaka’s Research never been shown conclusively that TU Darmstadt in Germany and Yang Centre for Nuclear alpha particles exist in nuclei. Zaihong at Japan’s Osaka University, Physics to spot the Stefan Typel from TU Darmstadt

used a high-energy proton beam to DarmstadtAumann/TU Thomas formation of alpha has previously calculated that alpha knock the clusters off the surfaces particles on neutron- particles should form in the neutron- of several tin isotopes. Their findings properties is understanding how protons rich skins of heavy rich skins of heavy nuclei. Now, Typel T-Station 300 could provide a better understanding of interact with neutrons. However, both nuclei. and colleagues have confirmed his radioactive decay in heavy nuclei and neutron stars and nuclei should obey prediction by using the 392 MeV proton provide insights into the compositions of the same physical laws governing how beam at the Research Centre for neutron stars (Science 371 260). neutrons and protons interact despite Nuclear Physics at Osaka University Heavy atomic nuclei tend to contain their very different sizes. As a result, to knock away alpha clusters from the many more neutrons than protons and studying the neutron-rich skins of nuclei surfaces of a variety of tin isotopes, nuclear physicists believe that these could shed light on the equation of state containing between 62 and 74 neutrons. nuclei have neutron-rich “skins” on their of neutron stars, which links the radius The team found that the probability of surfaces. An understanding of these of a neutron star with its mass. this happening decreases gradually skins could help astrophysicists to One way that protons and neutrons as their neutron numbers increase. develop models of neutron stars – super- could interact in a nucleus is to bind Conversely, the thickness of the dense objects about 20 km in diameter. together to form an alpha particle neutron skin is expected to increase While neutron stars are made (essentially a helium-4 nucleus). In with neutron number– confirming an mostly of neutrons, about 5% of their 1928 the theoretical physicist George interplay between alpha clusters and mass comprises protons – and one Gamow showed that alpha particles the thickness of neutron skins. © Edwards Limited 2021. All Rights Reserved. of the challenges of calculating their can quantum mechanically tunnel out Sam Jarman Plug & Pump Robust construction End user Low cost of Configurable serviceable ownership TIC Turbo Cart Physics World March 2021 7

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IOP webinars Biophysics A programme of talks and events for the physics community Spring and latch mechanism flings click beetles into the air

Click beetles use the elastic recoil of Click and release released. As a result, the beetle’s tho- a spring-like mechanism in their exo- X-ray imaging at the rax is flung in the opposite direction skeleton to throw themselves into the Advanced Photon and the insect fires itself into the air. air. The mechanism of the insects’ Source has shed John J Socha The X-ray images show that the motion was discovered using high- light on the click peg reaches a maximum velocity of speed synchrotron X-ray imaging. beetles’ impressive 1.8 m/s during the energy release and The team says its techniques could jumping abilities. a maximum acceleration of more further our understanding of how than 500 times the acceleration due Future webinars include: animals perform ultrafast move- to Earth’s gravity. The images also ments as well as novel techniques for show that the deformation in the soft energy storage (Proc. Natl Acad. Sci. sity of Illinois Urbana-Champaign cuticle is released in less than 1 mil- 118 e2014569118). and colleagues took four beetle lisecond, which is much faster than Small creatures like fleas, mantis specimens to the Advanced Photon the loading time. This supports the The role of solar technologies shrimp and trap-jaw ants produce Source at Argonne National Labora- idea that click beetles can amplify some of the fastest movements in tory. Using a high-speed synchrotron mechanical power during the click- the animal kingdom. These extreme X-ray imaging system, they captured ing motion and is characteristic of an in sustainable development accelerations are powered not by the beetle’s internal movements at elastic recoil. muscles, but by complex energy stor- rates of 30 000 frames per second. Despite the power they generate, age and amplification structures. In The high-speed X-ray recordings Wissa says that the beetles can click 29 March 2021 the case of the click beetle, Elater show that the click has three phases: repeatedly without apparent injury. abruptus, it can jump more than 20 latching, loading and energy release. “We found that the energy is dis- body lengths without using its legs. To “latch”, the beetle moves its head sipated using a nonlinear damping Using a latch on the underside of and thorax away from the underside force,” she says, adding that more its exoskeleton, it bends its body of its body, causing the peg to slide research is needed to know the exact Quantum Dot Day at a hinge between a peg on the over and latch onto the lip. During mechanism. Yet understanding the thorax and a lip on the abdomen. the loading phase, the beetle main- physical mechanisms that small When the latch releases, the beetle tains this bend in its body while the animals use to achieve extreme 29 March 2021 unbends extremely quickly, makes a soft cuticle behind the peg deforms accelerations could have biomimetic loud clicking sound and – if uncon- and stores elastic energy, acting like a applications such as the design of strained – leaps into the air. spring. After this contraction – which new “actuation strategies for small To record the rapid movement of takes around 240 milliseconds – the mechanical systems where power the mechanism, mechanical engi- peg slips, the latch unlocks and the might be limited,” says Wissa. Magnetism 2021 neer Aimy Wissa from the Univer- energy stored in the cuticle is rapidly Michael Allen 12-13 April 2021 Accelerating egg yolks shed light on brain injuries New insights into how brain injuries Brain food yolks only deformed slightly in occur have been gleaned from how an Researchers have response to translational impacts egg yolk is deformed when rotational discovered that egg but were highly sensitive to rotational forces are applied to its outer shell. Ji yolks are only impacts – particularly those involving Lang, Rungun Nathan and Qianhong deformed slightly in deceleration. In this case, the Wu at Villanova University in the US, response to researchers determined that the fluid conclude that brain injuries are far translational pressure outside the yolk initially more likely to result from rotational Biswarup Ganguly/CC BY 3.0 impacts but were becomes larger than the centrifugal impacts on the skull than from direct highly sensitive to force of the fluid enclosed by its delicate translational impacts. Their work rotational impacts. membrane, leading to compression at provides new insights into how soft the centre of the yolk. However, if the matter behaves and could lead to a the similarities between the brain outer shell’s rotation suddenly stops, better understanding of how certain with a simpler system: a soft egg yolk these centrifugal forces will become sports injuries occur (Physics of Fluids surrounded by fluid white and encased far greater than the outside pressure. Register at iop.org/eventsandtalks 33 011903). in a hard eggshell. Wu and colleagues This means the yolk will no longer hold The human brain is surrounded by examined how egg yolks deform its shape and will expand into the a thin layer of cerebrospinal fluid and during non-destructive translational surrounding fluid. The team’s results encased in a hard skull. It is now widely and rotational impacts on their outer offer new insights into why brain injuries believed that sudden translational shells. To do this, they devised a simple appear to be more likely to occur after and rotational impacts on the skull experiment involving a kitchen gadget certain types of impact, particularly in will temporarily deform the soft brain, that scrambles an egg in its shell. This sports. The research may also inform potentially causing serious injury as allowed the team to subject yolks to a future studies of membrane-enclosed intricate networks of neurons are variety of shear and spinning flows and soft matter, including red blood cells disrupted. To study these impacts in image their deformation over time. and spinning droplets. iop.org further detail, Wu’s team exploited The images revealed that the Sam Jarman

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 Frontiers physicsworld.com Sextuply-eclipsing star system discovered An unusual grouping of six gravitationally bound stars is more than an astronomical curiosity and could shed light star formation, as Keith Cooper explains

A system of six gravitationally bound and Max Moe of the University of stars – each of which eclipses the Arizona, US, proposed that such “partner” star in its binary pair – has migration could be driven by gas been identified by researchers who accretion from a protostellar nebula used machine learning to locate its surrounding the stars when they are signal within the vast datasets gener- still young. Because close binaries ated by NASA’s Transiting Exoplanet are often found in triple or quadru- Survey Satellite (TESS). The discov- ple star systems, Tokovinin and Moe

ery of this unusual grouping is both NASA Goddardsuggested Space Flight Center that gas accretion could a step forward in our understanding not only drive a binary system closer of complex multi-star systems and an together but could also provide example of how artificial intelligence enough gas to form more stars. is enhancing astronomical observa- Tokovinin thinks that a similar tions (arXiv:2101.03433, to be pub- thing may have happened in TIC lished in The Astronomical Journal). 168789840, but on a grander scale. Although binary- and triple-star The similarities between the three systems are common, groupings of primary stars, he says, “prompts six stars are much less so. Only 18 sual or complex multiple star systems Six-fold needle in the idea that the original primaries, sextuplet systems have so far been within the TESS data. This analysis a haystack A, B and C, were already forming a identified, and a sextuply-eclipsing led the NASA Goddard Space Flight Data scientists used bound triple and acquired their com- sextuplet system like the one des- Center team to TIC 168789840’s observations from panions at the same time, [perhaps] ignated TIC 168789840 is rarer multiple eclipses. NASA’s Transiting when this triple passed through a still – perhaps even unique. This is One puzzling feature of TIC Exoplanet Survey dense gas cloud”. In this scenario, because the stars’ orbital plane must 168789840 is that the primary stars Satellite to identify a the gas that accreted from the cloud be almost edge-on with our line of in each of the three binaries all have complex system of onto the triple system was enough to sight here on Earth for us to see the very similar masses (between 1.22 six eclipsing stars. form the three smaller secondaries. stars eclipse their partners as they and 1.30 times the Sun’s mass), radii As they formed, this same accretion orbit their common centre of mass. (between 1.46 and 1.69 solar radii) process led them to migrate inwards, While this alignment is more com- and temperatures (between 6350 becoming closer to their primary mon in close pairs of stars like the and 6400 K). Their partners, mean- stars. Hence, what started as a triple ones that make up TIC 168789840, while, are all K-type stars, smaller system, with two stars orbiting one the probability is still less than 20%, and cooler than our Sun. Such simi- another and a third orbiting them says Brian Powell, a data scientist at larities are “interesting because it is both, became a system of six stars. NASA’s High-Energy Astrophysics yet another improbable characteris- “[The system] provides an excep- Science Archive Research Center tic of this star system”, adds Powell. tional laboratory in which to study (HEASARC). “The chance that A further puzzle is that the three possible formation scenarios,” Pow- High-density wiring a sextuple would contain all three pairs of stars in the system orbit one ell says. “It could be the smoking gun binaries oriented in such a manner another at relatively close distances. for the accretion-migration model of is quite small, not to mention the The stars in A and C are 4.8 and 4.2 close binaries.” Our new high-density wiring is a rarity of the sextuple-system for- million kilometres apart respec- Powell says that TESS is “a gold- modular option for the Bluefors side- mation to begin with,” Powell told tively, while the stars in the outer mine of interesting data” and more loading XLDsl dilution refrigerator Physics World. binary, B, are separated by 14.9 mil- discoveries will be made. “I have lit- At the heart of the system are two lion kilometres. By way of compari- tle doubt that there is a larger star system that enables a large scale-up pairs of eclipsing binary stars, desig- son, Mercury, the innermost planet system than this one in the data, of the experimental wiring, especially nated pair A and pair C. Each star in in our solar system, gets no closer to simply waiting to be found,” he adds. for high-frequency signals. It is easy pair A and pair C orbits its partner the Sun than 47 million kilometres. Indeed, Ulrich Kolb, an astrophysi- to install and to maintain. in a matter of days. Pairs A and C While closely spaced binary stars cist who studies star formation at the also, collectively, orbit their shared are not uncommon, they pose a Open University in the UK but was centre of mass. Finally, a third eclips- challenge to star-formation models, not involved in the discovery, says ing binary, pair B, is located farther which predict that stars should not that the eclipses in TIC 168789840 out and orbits the A–C pair. An be able to form within 1.5 billion are more than just an astronomical eclipse occurs whenever one star in kilo metres (10 AU) of one another. It could be curiosity. They also reveal a wealth the system is seen to move in front To resolve this apparent contradic- of information about the six stars of its fainter partner (a primary tion, astronomer Andrei Tokovinin the smoking that could otherwise only be deter- eclipse) and then behind it (a sec- from the Cerro Tololo Inter-Amer- gun for the mined using sophisticated stellar ondary eclipse). Powell and Veselin ican Observatory in Chile, suggests accretion- models. “All of [the models] have Kostov used machine learning and that the stars in TIC 168789840 and migration intrinsic assumptions and ambigui- artificial intelligence tools devel- other close binaries may have formed ties,” he says. “So finding an eclips- oped by astrophysicist Alan Smale in other locations and then migrated model of close ing system like TIC 168789840 is a and colleagues to help identify unu- closer together. In 2020 Tokovinin binaries bit like striking gold.”

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Astronomy UAE Hope probe reaches Mars orbit Planetary missions could hunt for gravitational waves The United Arab Emirates has become the first Arab country to reach another planet – a feat that it Spacecraft heading to Uranus and Listening in measurements of the planetary hopes will turbocharge its science base, as James Dacey reports Neptune in the next decade could Proposed missions gravitational fields,” says Soyuer. be used to investigate gravitational to Uranus and “[It] sounds easy in principle, but the The $200m Emirates Mars Mission Out of this world waves as they venture into the outer Neptune in the next changes in frequency that we want to

successfully arrived in Martian orbit The United Arab MBRSC solar system. That is according to decade could be detect are extremely small.” last month, concluding its seven- Emirates’ Hope a new study by a team of Swiss and used to detect Another technical challenge would month journey to the red planet. The mission will study Danish researchers, who say that gravitational waves be noise in the data. Among the

arrival of the United Arab Emir- the Martian examination of the radio signals as they travel on Gill M NASA/JPL-Caltech/Kevin main contributors to this would be ates’ (UAE) probe – named Hope atmosphere, from far-flung probes might reveal their way. the mechanical noise of the antenna – marks the beginning of the science studying daily and the signature of these subtle ripples Kuiper belt. What a future genera- listening in back on Earth. But if stage in the first interplanetary voy- seasonal changes in in the fabric of space–time as they tion of outer planet explorers would those hurdles can be overcome with age undertaken by an Arab nation. the climate. roll across our planetary neighbour- have on their side, though, is time. advances in technology, the missions As Physics World went to press, the hood (arXiv:2101.11975). Proposed missions to Uranus and could potentially detect the gravita- 1500 kg craft was undergoing fur- The scientists say that gravitational Neptune – which planetary scien- tional waves given off by bodies – such ther manoeuvres and testing before waves would make themselves known tists hope might launch around 2030 as stellar-mass black holes – whirling it begins returning science data from through a Doppler shift in the trans- – would take many years to reach around gargantuan black holes. They the Martian atmosphere. missions from distant spacecraft. their targets, meaning they would may also be able to pick up the space– Mission control at Dubai’s “When a gravitational wave passes have several opportunities to carry time ripples emanating from collid- Mohammed bin Rashid Space Cen- after Hazza al-Mansouri became Rashid, to the Moon in 2024 and to through, it can slightly disturb the out searches for the elusive undula- ing supermassive black holes. tre (MBRSC) received a signal, the first Emirati in space when he build a “Mars Science City” in the radio link by shifting its frequency. tions. “There is one-and-a-half to If detections do occur, they could relayed from NASA’s Deep Space spent eight days on the International desert outside Dubai – a research We can detect the small deviations two months of ideal time in a year to provide a “nice overlap” with obser- Network, on 9 February to confirm Space Station. facility that will eventually host ana- in the carrier frequency we receive do these kinds of observations when vations by Europe’s upcoming grav- that the car-sized spacecraft had Having established a national space logue “missions to Mars”. from the spacecraft and deduce that the Earth–Sun–spacecraft angle itational-wave mission, LISA, says entered into a stable orbit. That fol- agency in 2014, the UAE quickly built By investing heavily in space a gravitational wave has passed,” becomes favourable,” explains Soy- Laura Nuttall from the University lowed a nail-biting half hour as Hope up its space capacity by collaborat- exploration, the UAE hopes to kick- explains Deniz Soyuer from the Uni- uer. “So a 10-year cruise time would of Portsmouth who is a member of fired its Delta V thrusters, slowing ing with established space nations. start its science and engineering sec- versity of Zurich, who led the work. yield a total of 10 one-and-a-half- the LIGO scientific collaboration. its speed from over 121 000 km/h Launched from Japan’s Tanegashima tors, to diversify its economy away Similar gravitational-wave hunts month long observations.” “[These missions] are more likely to approximately 18 000 km/h to Space Center in July, the Hope space- from oil. Since the Hope mission was have been attempted – without suc- The technique would also not to see different events than LIGO/ be captured by Mars’ gravity. “We craft was built in partnership with first mooted in 2014, mission leaders cess – by previous missions. In prin- require any dedicated on-board Virgo are sensitive to as they are congratulate our leadership and the Laboratory for Atmospheric and have spoken regularly about how it ciple, it is even something that could equipment to be fitted to the probes. probing a different part of the grav- our people of all nationalities in the Space Physics (LASP) at the Univer- can foster interest in science among have been tried with NASA’s New “All missions already have Doppler itational-wave spectrum,” she says. UAE,” noted Sarah Al Amiri, chair sity of Colorado, Boulder. The mis- students. Under broader plans out- Horizons spacecraft, which is cur- tracking instruments on them, since “So just like LISA, [they] would com- of the UAE Space Agency via Twit- sion team comprises 200 staff from lined in 2017, the UAE set the tar- rently traversing the remote region that is how you track the spacecraft plement LIGO/Virgo.” ter. “The science team has a lot of MBRSC, 150 from LASP, along with get that “knowledge workers” would of our solar system known as the and also conduct gravitational field Will Gater work to do, and we are confident that support from an international sci- make up 40% of its total workforce they will make new, great and big dis- ence team and roughly 100 partners. by the end of 2021. China’s Tianwen-1 Mars mission sends back first image as it plots rover landing site coveries about the red planet.” “The UAE could have easily just “The UAE’s Mars Mission is a purchased a spacecraft to go to clear reflection of the UAE’s vision China’s Tianwen-1 probe has beamed back its Weather watcher Mars, but they had a goal to build and ambition,” says Sanam Vakil, a first picture of Mars, days before it entered orbit Hope’s main scientific objective is it, not buy it,” says LASP engineer Middle East researcher at Chatham around the red planet on 10 February. Tianwen-1, to study daily and seasonal weather Brett Landin, who leads the mis- House, an independent policy insti- which means “Quest for Heavenly Truth”, sent a changes, as well as observing how sion’s spacecraft team. “I think the tute in the UK. “The project is black-and-white picture of the red planet taken hydrogen and oxygen are lost into most fascinating part of this mission designed to promote the knowledge- when the probe was around 2.2 million kilometres space. This data could provide a has been watching a nation decide to based economy while also inspir- from Mars. Launched in July last year, the probe better understanding of how Mars institute a meaningful change and ing Emiratis and attracting other is China’s first mission to Mars and will orbit the turned into the dusty barren planet then actually make it happen in a regional nationals to the Emirati planet before landing a rover on the surface. It is we see today. Hope carries three very short period of time.” economic model.” Administration Space National China hoped that it can gather important information main instruments: an infrared and Hope was the first of three sepa- about the Martian soil, geological structure, an ultraviolet spectrometer as well The UAE could Building a ‘knowledge economy’ rate missions arriving at Mars and environment and atmosphere, as well as search as an imager that will study the lower have easily just It may still be early days, but the was swiftly followed by China’s for signs of water. The probe will now study the atmosphere at visible and ultraviolet purchased a UAE has grand ambitions for space Tianwen-1 spacecraft, which arrived landing spot, which is expected to be a flat plain wavelengths. exploration. Hope is just one pro- in orbit on 10 February (see oppo- within the Utopia impact basin just north of Sending a mission to Mars was a spacecraft to ject in the nation’s “Mars 2117” site). As Physics World went to press, Mars’ equator. The as-yet-unnamed rover, which bold statement from the UAE, an go to Mars, but programme, which has the ultimate NASA’s Perseverance rover suc- has a similar appearance to NASA’s Spirit and Arabian state with a population of they had a goal goal of establishing the first human cessfully landed on Mars and began Opportunity rovers from the 2000s, will be sent to 9.8 million that gained independ- to build it, not settlement on Mars within the next searching for signs of ancient life in a the surface in May or June. ence from the UK in 1971. The century. Other key projects are to Martian crater that was once flooded Michael Banks achievement came just three years buy it send an unmanned rover, dubbed with water.

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Education ‘Dismay’ at global standards for school geoscience

Despite growing demand for geo- lesson plans and resources for teach- scientists around the world, the ing earth science, fewer are provided attainment achieved in school-level with specific geoscience courses. earth-science education is bleak. Only a third of countries offer pro- That is the conclusion of an interna- fessional development programmes tional survey by UNESCO and the in teaching earth science, while very iStock/SDI ProductionsiStock/SDI International Geoscience Education few offer financial resources for Organisation, which found that more developing geoscience lessons. than half of the countries studied Geoscientist Chris King from either have no national educational Keele University, who led the sur- standards for earth science or they vey, is dismayed by the results. He are not followed. says that a similar survey conducted The survey canvassed the opin- in 2013 was “bleak but not quite as ions of experts from 51 countries, bleak as this one”. King told Physics comprising more than half the global World that it is distressing that earth population. Respondents included science is in many national curricula, educational researchers, academics, Grounds for ing material is available in around but is not widely followed by teach- employees in national ministries or concern 80% of the countries surveyed, ers. “We know why they don’t follow agencies for education, and teach- A survey of 51 according to the respondents, but the curriculum, and that’s because ers. They reported that earth sci- countries’ earth- they consider it to be only of “mod- they haven’t been taught very well,” ence forms part of the curriculum science teaching erate quality” in almost two thirds he says. “They don’t understand it. in 75% of countries surveyed, but found that national of countries and “poor quality” in They haven’t really developed an these national standards are only standards are only around 10% of nations. Careers interest in it.” closely followed in 46% of countries. kept in half of cases. advice is also lacking, with very little King adds that getting people In the rest they are either not closely or no careers advice relating to earth interested in, understanding and followed or do not exist. science available to students in three working in earth science is crucial Three quarters of the countries quarters of the countries surveyed. to tackling climate change. “A huge surveyed have standardized assess- Most earth-science teachers, the amount of climate change, both what ments, but, on average, only a quarter report found, are non-specialist. causes it and what can stop it hap- of these feature earth-science ques- And while teachers in more than pening, comes down to geoscience.” tions. Written earth-science teach- half the countries are provided with Michael Allen

Funding France unveils huge €1.8bn quantum technologies boost

France has announced it will invest Quantum France in the leading circle of countries €1.8bn over five years to advance enthusiast capable of mastering quantum quantum computing technologies in the Unveiled by technologies in a sustainable manner,” country. The plan was officially unveiled Emmanuel Macron, noted Macron. “It is nothing less Vacuum solutions by French president Emmanuel Macron France aims to be than achieving our independence in a on 21 January during a visit to the Paris- among the first to technological domain that will shape Saclay campus – a major scientific and produce a complete the future.” He adds that “quantum technological cluster currently under prototype of a first- technologies are among the keys to the construction. It will place France third in CC BY-SAgeneration EU Estonian Presidency general- future that France must master”. from a single source the world – after the US and China and purpose quantum Philippe Chomaz, scientific director of ahead of the UK and Germany – in terms computer. fundamental research at the CEA, says Pfei er Vacuum stands for innovative and custom vacuum solutions worldwide, technological of investment in quantum technologies. that the quantum revolution has already perfection, competent advice and reliable service. We are the only supplier of vacuum technology The “Quantum Plan” includes the begun, and that it is already impacting development of quantum simulators and companies such as Total, Atos, aspects of quantum information that provides a complete product portfolio: as well as research into quantum Airbus, Thales, STmicroelectronics and technology. He says there are three sensors, post-quantum cryptography Air Liquide. The remainder will come links in the “quantum chain”: quantum and quantum communications. It also from the Investments for the Future sensors; quantum communication; ■ Pumps for vacuum generation down to UHV includes the ambition to make France Programme and research organizations and quantum computing. “These three ■ Vacuum measurement and analysis equipment among the first to produce a complete including the French National Centre fields are at the heart of the new ■ Leak detectors and integrity test systems prototype of a first-generation general- for Scientific Research, the French quantum plan together with a fourth purpose quantum computer. As part of Alternative Energies and Atomic Energy – fundamental research – without ■ Vacuum chambers and components the plans, €1bn will be directly financed Commission (CEA) and the National which real-world applications are not ■ Pumping stations and customized solutions by the government, €200m will come Institute for Research in Digital Science possible,” Chomaz says. from European credits and €550m from and Technology. Isabelle Dumé the private sector – via investment funds “With this plan, we aim to position Paris Are you looking for a perfect vacuum solution? Please contact us:

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US Sidebands

Estonia joins CERN club MIT scientist backed over China links Estonia has become an associate member of the CERN particle-physics lab near Geneva following an agreement

More than 200 researchers at the MIT Massachusetts Institute of Tech- that was signed in June 2020 and has nology (MIT) have signed a letter now been officially approved by the supporting nanotechnologist Gang government. For the past two decades, Chen, who was arrested and indicted scientists from Estonia have worked in January on charges related to on several CERN programmes such as his links with research institutions the CMS Collaboration at the Large funded by the Chinese government. Hadron Collider (LHC) as well as the Chen, a naturalized American citi- worldwide LHC computing grid, the theory zen born in China, is charged with department and in the development of Instruments for “failing to disclose that he was acting the Compact Linear Collider project. As as an ‘overseas expert’ on science and an associate member, Estonia is now technology for the Chinese Commu- entitled to participate in CERN council nist government…in exchange for and scientific policy meetings. Estonia’s financial compensation and awards”. nationals are also eligible for limited- Advanced Science The letter, addressed to MIT Centre of attention environment for Chinese research- duration staff positions and fellowships, president Rafael Reif, states that the Gang Chen, who was ers is something that we don’t want.” and its companies are entitled to bid for researchers are “concern[ed] both arrested and The issue comes as little surprise CERN contracts. on the allegations against Chen and indicted in January to physicist Xiaoxing Xi from Temple Mass spectrometers for vacuum, gas, plasma and surface science its implication for open academia on charges related to University. In 2015 the FBI charged Arnold Wolfendale dies aged 93 and intellectual freedom” and are his links with Xi with illegally sending sensitive The astronomer Arnold Wolfendale has “troubled that the complaint against research institutions technology to China, only to admit died at the age of 93. Born in Rugby in Chen vilifies what would be consid- funded by the later that agents had misidentified central England in 1927, Wolfendale ered normal academic and research Chinese government. the technology. “From my own per- graduated in 1948 with a BSc in physics activities, including promoting sonal experience, what the govern- from the University of Manchester before MIT’s global mission”. The charge ment charges is not necessarily true,” completing his doctorate in 1953. He against Chen specifies a payment of Xi told Physics World. Speaking at a then moved to Durham University in $19m from China’s Southern Uni- recent colloquium at Harvard Uni- 1956 where he remained until retiring versity of Science and Technology. versity Xi said that persecuting lead- in 1992. Best known for his work on the However, the faculty members’ let- ing researchers who collaborate with origins of cosmic rays, Wolfendale was ter notes that MIT, not Chen, was Chinese colleagues and making it also president of the Royal Astronomical the recipient of this money, which untenable for Chinese scientists to Society from 1981 to 1983 and later “benefited the institute, the research have a life and career in the US is became Astronomer Royal from 1991 programmes of many of its faculty, “destroying American science and to 1995, where he worked to promote Residual Gas Analysis and its students”. technology”. astronomy and campaigned for better Yoel Fink, a materials scientist The news comes after NASA nano- funding for all the sciences. From 1994 to Perform RGA at UHV/XHV . Our RGA configurations include systems for UHV and electrical engineering at MIT, technologist Meyya Meyyappan 1996, Wolfendale served as president of science applications including temperature-programmed desorption and who organized the letter, sees the pleaded guilty in January to making the Institute of Physics, which publishes issue as one of government misun- “false statements” to US government Physics World. electron/photon stimulated desorption. derstanding of the global nature of authorities over his links to China scientific research. “Casting doubt (February p11). Meanwhile, Amer- Giorgio Parisi bags Wolf prize about our loyalty and the framework ican-born Charles Lieber, chair of The theoretical physicist Giorgio Parisi in which we operate is something we Harvard’s Department of Chem- from the University of Roma I ‘‘La don’t want,” says Fink. “If we heard istry and Chemical Biology, also Sapienza’’ has been awarded the 2021 Thin Film Surface Analysis of a professor arrested in another awaits trial on a charge of making Wolf Prize for his “ground-breaking Conduct both static and dynamic SIMS analysis with a choice of primary ions country, we would complain. So why false statements to authorities about discoveries in disordered systems, aren’t we raising the same level of his connection with China’s Thou- particle physics and statistical physics”. for full chemical composition and depth profiling. Our SIMS solutions include alarm in this country?” sand Talents Programme. “What is Parisi worked at Italy’s national institute MIT has committed to paying so striking,” Lieber’s lawyer, Marc for nuclear and particle-physics research complete workstations and bolt-on modules. Chen’s legal fees. It has also agreed Mukasey, said in a statement to from 1971 to 1981, before moving to to provide him with information he Physics World, “is that MIT has been the University of Roma II “Tor Vergata” needs to defend himself in court and supportive of Professor Chen and where he spent a decade. He then went to support his students and research appears to respect the presumption to La Sapienza in 1992. Parisi’s work Plasma Characterisation activities. And according to Fink, of innocence. Harvard, on the other has touched on several areas of physics faculty members of other universi- hand, has pushed Professor Lieber in from studying how quarks and gluons Fully characterise a range of plasmas: RF, DC, ECR and pulsed plasmas, including ties, including Northwestern and front of the train to save itself, and are distributed inside the proton and Stanford, are working on their own cares not about the bedrock concept nuclei to “spin-glass” systems. The Wolf neutrals and neutral radicals. Extend your analyses to atmospheric pressure messages of support for Chen. “This of “innocent until proven guilty”. Foundation said in a statement that processes using the HPR-60, with time-resolved mass/energy analysis. has to do with any research univer- Mukasey added that “there will be Parisi was awarded the prize for “being sity in this country, not just MIT,” no guilty plea” by Lieber. one of the most creative and influential he says. “The idea of criminalizing Peter Gwynne theoretical physicists in recent decades”. scientific activity and creating a toxic Boston, MA

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 News & Analysis physicsworld.com Concerns raised as Oxford renames physics chair The University of Oxford has announced that its Wykeham chair of physics will be renamed after the giant Chinese technology corporation Tencent, which denies claims it has links with the Chinese security services. Michael Allen reports

The University of Oxford is to and all our universities,” he told the rename its Wykeham chair of phys- newspaper. “I’ve got no doubt at all ics as the Tencent-Wykeham Chair that there are serious strategic and as part of a five-year £700 000 dona- Shutterstock security issues at stake.” tion from the Chinese conglomerate Tencent. The professorship, which Monitoring links is the only endowed chair in the The renaming of the Wykeham Rudolf Peierls Centre for Theoreti- chair of physics coincides with a new cal Physics, has been vacant since the report by the UK think tank CIVI- condensed-matter theorist David TAS, which highlights what it calls Sherrington retired in 2008. Accord- the “pervasive presence of Chinese ing to Oxford’s physics department, military-linked organizations in the appointment of the next chair is high-technology research centres in progress. Other previous hold- in many leading UK universities”. ers of the post include Willis Lamb, According to the 117-page report, Roger Elliot and Peierls himself. China connection ducted transparently, in good faith which was published last month, the Founded in 1988, Tencent is cur- The Wykeham chair and without conditions”. “We have UK government needs to improve rently worth more than $500bn and is of physics at the deep respect for the rich history and monitoring of Chinese involvement one of the world’s most valued com- University of Oxford innovative future of the UK’s higher in UK research, calling current panies. More than a billion people will now be named education establishments, and are methods “inadequate”. It claims use its WeChat communications app, the Tencent- pleased to support their missions of that 15 of the 24 universities in the which the company says operates out- Wykeham Chair as learning, teaching and research,” the prestigious “Russell Group”, as well side China, and the sister app Weixin, part of a £700 000 spokesperson added. “As a publicly as many UK academic bodies, have which operates within China. The donation by the listed global company we hold our- research relationships with Chinese tech giant is also known for online Chinese firm selves to the highest standards, and military-linked universities and with gaming and many other Internet- Tencent. our policies and procedures comply weapons suppliers or other defence related services and products. with all laws and regulations in each firms. Oxford was not one of those Tencent has, however, faced con- country in which we operate. User 15 universities. troversy. It has denied claims made by privacy and data security are core val- Written by Radomir Tylecote and the CIA that the company received ues at Tencent, and we look forward Robert Clark, the report says that funding from China’s Ministry of to continuing to sustain user trust and these institutions are often unin- State Security when it was founded. delivering great user experiences.” tentionally generating research Tencent has also faced criticism that, A University of Oxford spokesper- that is sponsored by and may be due to Chinese law, the company son, meanwhile, told Physics World of use to Chinese firms that pro- shares user data from its messaging that the university has “a rigorous duce intercontinental ballistic and apps with the Chinese government. due diligence process and Tencent hypersonic missiles, nuclear war- In a report by Amnesty International has been approved as an appropri- heads, stealth aircraft and military in 2016, which examined how 11 mes- ate donor by our independent com- drones. Tylecote told Physics World saging apps use encryption to pro- mittee to review donations, which that research areas with frequent tect users’ online privacy, Tencent includes independent, external rep- links are aerospace physics and received a score of 0 out of 100. resentatives”. The spokesperson did hypersonic technologies, metals and not confirm the value of the dona- alloys, and data science. Chinese Philanthropic affairs tion but said the university has a sponsorship also covers research News of the renaming of the profes- “very clear position” on academic such as ceramics, piezoelectrics, sorship was broken last month by the independence from donations. “Our rare-earth metals, drones and radar, Daily Mail, which quoted Richard donors have no say in setting the shipbuilding and robotics, he says. Dearlove, a former head of MI6, say- Tencent research and teaching programmes Much of this work will, however, ing he was “amazed” that Oxford had of the posts they fund, nor do they have a civilian use, the report states, agreed to the move for just £700 000. has been have any access to the results of with UK-based researchers being Former Brexit secretary David Davis approved as research, other than publicly avail- unaware of a possible dual military told the paper the decision was “very an appropriate able material,” they added. use despite much of the work being unwise”, while Iain Duncan Smith, a donor by Chris Patten, chancellor of the taxpayer-funded. CIVITAS sug- previous leader of the UK Conserv- University of Oxford and the last gests that the UK should set up a new ative Party, said that “to celebrate Oxford’s British governor of Hong Kong, said government organization similar Tencent by renaming this professor- independent he was unaware of the renaming of to the US’s Committee on Foreign ship is grotesque”. committee the chair until contacted by the Daily Investment to monitor and assess A Tencent spokesperson, however, Mail. “I’m strongly in favour of the university sponsorship. “It would told Physics World that the compa- to review proposal to do a comprehensive sur- expose UK universities to less risk,” ny’s philanthropic efforts are “con- donations vey of relationships between China Tylecote says.

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 ENESTEDT.SE physicsworld.com Comment Entangled thoughts Physics World Temple Circus, Temple Way, Bristol BS1 6HG, UK Tel +44 (0)117 929 7481 Research at the interface between physics and biology is rewarding and exciting E-mail [email protected] If someone says the word “entanglement”, do you picture pairs of photons shar- Web physicsworld.com Twitter @PhysicsWorld ing their quantum behaviour or do you see wriggly polymer chains tied up in a Facebook facebook.com/physicsworld knot? If you hear the word “nucleus”, does your mind turn to the super-dense Head of media Jo Allen core of an atom, or to the region at the heart of a cell containing its genetic infor- mation? Come to think of it, when anyone talks of “cells” do you think of batteries Editorial Editor-in-chief Matin Durrani or biology? News editor Michael Banks Physicists will be well aware of the difference between the terms I’ve mentioned, Features editor Tushna Commissariat Online editors Tami Freeman, Margaret Harris, but they illustrate a wider point about what we know (or can be expected to know). Hamish Johnston Scientific understanding is something Product and content that’s constantly on our mind here at Lead product and content manager Dens Milne Physics World, especially when editing Content and production manager Kate Gardner Head of technical illustration Alison Tovey features. Those articles go into much Sales and marketing more detail on a particular issue than, iStock/Credit:ktsimage Marketing and circulation Laura Gillham say, news or opinion pieces, but the Advertisement sales Chris Thomas, Tom Houlden question is how deep they should go. Advertisement production Mark Trimnell In the Art of Making Lasers Our approach is to edit features so The 2021 subscription rate for institutions is £460 per annum for that an article on a particular topic can the print magazine, £874 for the electronic archive, £1067 for combined print and electronic. Single issues are £43. Orders to: be understood by physicists outside Subscriptions Dept, IOP Publishing, Temple Circus, Temple Way, that field. Partly it’s a numbers game: Bristol, BS1 6HG, UK; tel +44 (0)117 929 7481; e-mail [email protected]. Physics World is available physics has so many sub-disciplines on an individual basis, worldwide, through membership of the that there will always be far more readers unfamiliar with an area than there will Institute of Physics be readers who know it inside-out. We therefore try to ensure that non-experts Copyright © 2021 by IOP Publishing Ltd and individual remain interested and can follow along, though I hope experts on a topic don’t contributors. All rights reserved. IOP Publishing Ltd permits single photocopying of single articles for private study or feel patronised but appreciate seeing their pet subject clearly presented with a research, irrespective of where the copying is done. Multiple fresh perspective and in a form they might wish to share with others. copying of contents or parts thereof without permission is in breach of copyright, except in the UK under the terms of the It’s a theme that was on my mind while editing the feature “Make or break: agreement between the CVCP and the CLA. Authorization of building soft materials with DNA” by Davide Michieletto from the University of photocopy items for internal or personal use, or the internal or personal use of specific clients, is granted by IOP Publishing Ltd Edinburgh (pp48–52). He’s a physicist camped at the interface between physics for libraries and other users registered with the Copyright and biology, which happens to be the area I worked on during my own PhD. In his Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $2.50 per copy is paid directly to article Michieletto describes studying how entangled DNA chains get broken up CCC, 27 Congress Street, Salem, MA 01970, USA and glued back together again with the help of certain proteins. Bibliographic codes ISSN 0953-8585 (print) If the gaps between different sub-fields of physics are large, the gulf is even ISSN 2058-7058 (online) CODEN PHWOEW wider between physics and biology. That’s why researchers working at the inter- Printed in the UK by Warners (Midlands) plc, The Maltings, face of the two fields have a tough time: there’s a new language and syntax to learn, High performance lasers with dependable excellence West Street, Bourne, Lincolnshire PE10 9PH as well as a lot of background to pick up on. It also makes editing such articles The Institute of Physics trickier than normal. Most Physics World readers probably know what a chromo- 37 Caledonian Road, London N1 9BU, UK some is, but what about gametes, restriction enzymes or topoisomerase proteins? Tel +44 (0)20 7470 4800 E-mail [email protected] Despite the language barrier, which I trust we’ve smoothed over as much as Web www.iop.org possible during editing, I hope you enjoy Michieletto’s article. Who knew that DNA behaves a bit like the elongated multi-molecular “micelles” found in soap C-WAVE. Tunable Lasers. Cobolt. Single & Multi-line Lasers. C-FLEX. Laser Combiners. and that you can use the molecule of life to make new kinds of topological materi- als? It certainly gives a flavour of what’s going at the intersection between physics and biology, which is rich in problems needing to be disentangled.

Matin Durrani Editor-in-chief, Physics World

The contents of this magazine, including the views expressed above, are the responsibility of the editors. They do not represent the views or policies of the Institute of Physics, except where explicitly stated.

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com Comment: Forum

Discover what’s out there Widening career aspirations

As children narrow down their those questions. Take the next step in your career with Physics World Jobs With funding from the UK Space Agency, career interests from an early I recently wrote a storybook called Are We age, Carol Davenport says it is Nearly There Yet? It features the ExoMars Search our comprehensive job listings and recruiter information to Rosalind Franklin rover that is set to launch important that they are brought in 2022, arriving at Mars a year later. In the find the perfect job for you at all stages of your career – whether you’re up with a positive attitude story, Rosie the Rover is heading to Mars an undergraduate, graduate, researcher or industry professional. but wakes up due to a solar storm. To help towards science her get back to sleep, Mission Control tells

Shutterstock/MonkeyImages Business her about all the other robots on other mis- Think back to your childhood. What did sions. This simple story is easy enough for you want to be when you grew up? In pri- children to understand and links to a love physicsworld.com/jobs mary school I wanted to be a special-effects of space that many of them already have. designer. I even wrote a letter to the BBC During a family session, a facilitator first asking how to be one, to which they replied reads the story before encouraging parents I should study physics and design technol- and children to re-read it. They then use ogy as well as draw and make models in my building blocks to create their own space spare time. Fast-forward many years and – robot and make a pretend surface of Mars although I am not a special-effects designer Early years Children can rule out careers in science for it to travel on, with the facilitator mod- – I am a physicist working at NUSTEM, at a very young age if they are not introduced – for elling the sorts of questions that families which aims to increase the diversity and instance through picture books – to the idea that could ask to help them explore the story number of young people choosing STEM science can be done by people like them. and the science a bit more. (science, technology, engineering and When we evaluated the project, we maths) careers. found that after the parents and carers had If you ask young children today what Children will only taken part, they felt more confident talking they want to do for a job, they will give a about space with their children. Of course, relatively narrow range of possible careers. know about a few this sort of activity does not have to be an Last year, we asked more than 600 children organized event. Families can encourage between the ages of seven and 11 that ques- children to ask questions about their story- tion, finding that the 20 most mentioned jobs, often those books, build models or draw pictures about jobs accounted for 75% of all aspirations whatever they are reading. It can be any (bit.ly/36gNrta). They included doctor, vet, they hear about or story book, and we have gathered together sports coach and police officer. Of course, a list of more picture books with a science this makes sense – children will only know see around them theme for young children (bit.ly/39iP3oa). about a few jobs, often those they hear about or see around them at home or at school. Starting young More worryingly, however, was that school children are fascinated by science Although career choices seem a long way although some jobs were mentioned by boys topics such as space, and might want to off, I believe parents and families can help and girls, career aspirations were strongly “become an astronaut” to follow up their their children to be aware of the broadest gendered. Footballer and YouTuber, for interest, but parents might not feel confi- range of possible careers as they grow up. example, were the most popular careers dent talking to their child about space and We know that in more normal times, many given by boys, while vet and teacher were its mysteries, or about how there are lots primary schools welcome visitors to talk most popular with girls. In fact, our earlier of jobs linked to space exploration that to children about their jobs and what they research on career aspirations in primary go beyond astronaut. Without encourage- do, often under the title of “people who school showed that children are making ment, the child may subconsciously think help us”. However, these visitors tend to be choices about what they don’t want to do this means that science is not for them or people such as local police officers, health- before they are eight years old (Interna- their family. Over time, these interactions care workers and fire-fighters. If you are a tional Journal of Science Education 42 764). steer children away from a career related STEM professional, I would encourage you We therefore must talk to children about to science. to talk to children in primary schools about future jobs and careers much earlier than At NUSTEM, we have been developing yourself, and your job. In that way, we can has traditionally been the case. story time activities for nursery-aged chil- help children see that science is often about dren and their families. Although we do not asking questions and finding solutions to It’s good to talk directly talk about careers in the session, problems and that it can be done by “peo- Parents and families are strong influences we try to make conversations about science, ple like them”. on a child’s attitudes and interests. Those technology, engineering and maths “nor- who did not study science beyond the age mal” in the family. By working and playing Carol Davenport is an associate of 16 can feel that science is about “know- together, the children and adults enjoy the professor at Northumbria ing stuff”. This might mean that when their story and activity and then ask each other University, UK, and director of child wants to talk to them about an aspect questions. The aim is to help families to dis- NUSTEM (nustem.uk), e-mail of science or asks a good science question, cover that science – and of course physics carol.davenport@northumbria. families are uncomfortable and close the – is about asking good questions and decid- ac.uk conversation down. Indeed, many pre- ing on good ways of finding out answers to

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com Comment: Forum Supporting science in difficult times

With COVID-19 fostering anti- factual concerns can add a different, some- times unwanted complexity. Alternatively, science conspiracies, constant mental stimulation and problem Caitlin Duffy says that scientists solving is a thriving point for some scien- tists who use such interesting conversations have a duty to speak up and as a break – or indeed, procrastination – Shutterstock/Yeti studio Shutterstock/Yeti from their day-to-day work. challenge misinformation The demand for and of scientists is high. But we know that for every scientist who Every minute of every day some 300 hours chooses to be vocal, there is another who of video is uploaded to YouTube and mil- is loathe to fill such an open role, not least lions of stimulating but unregulated discus- because they do not have the time. Indeed, sions occur daily on forum sites. While the speaking up and putting yourself out there Internet allows instant access to informa- Identity question We can combat anti-science is not always easy. The response from tion and each other, the bias of algorithms ideology directly or by publicly breaking stereotypes those outside of the community is some- favour suggestions that appeal to the user. that mean scientists are “othered” and mistrusted. times ostracizing and offputting: rife with Alongside media sensationalism and politi- misogyny for women, judgemental towards cal corruption, the Internet has cultivated people of colour, and filled with the mis- an insurgence of anti-science ideology, The demand for and conception that scientists believe they’re fuelled by misinformation, under-repre- better than the general public. sentation and angered passion. In a world of scientists is high This, in combination with an often unre- where nearly 60% of the population has latable day job, can lead scientists to reduce access to the Internet, scientists are needed fully, new US president Joe Biden is taking their social ties to non-scientists, ultimately more than ever to safeguard facts, reliabil- a different approach. removing an indispensable connection ity, global peace and health. When influential people show such dis- with most of the population. Part of being Anti-science rhetoric has nucleated in the regard, disrespect and suspicion regard- vocal is to also break down stereotypes and past decade, especially when it comes to the ing science, it’s easy to understand how defy stigma. Doing so demonstrates the climate. Despite the worst-case scenario conspiracies are formed and cultivated in “normality” lying behind the graphs, liq- showing a global temperature increase of communities, giving rise to the danger- uid nitrogen and serious statistics; behind 8 °C and a sea level rise of 1 m by 2100 – well ous anti-science crusade. The role of a every scientist is a unique person with dis- within the lifetime of our youngest genera- scientist is to be the elective voice of rea- tinct interests, families and stories. This is tion – many opt to ignore it or challenge son against absurdity and tunnel-visioned crucial to portray if today’s young people the underlying evidence. In the wake of proclamations. It is vital then that figures of are to grow up with trust and passion in COVID-19, ignorance and a failure to lis- authority trust scientific judgement and act science and if minorities are going to feel ten to scientists has exacerbated the prob- correspondingly. The trust of politicians welcomed into the scientific community. lem. Onlookers watch as countries guided and the media can help to combat anti-sci- People are often taken aback should a by science slowly return to a cautious nor- ence rhetoric and some of the most pressing scientist have unexpected hobbies – be it mality, while other countries suffer painful issues faced by humanity. With the obvious bodybuilder, pro-chef, sommelier, artist or death rates, long-term lockdowns and frus- need for visible scientists, it should be our musician. When the outside world only sees tration at U-turns in policies. duty to speak up about our concerns about “scientist” as one’s identity, it inadvertently In the UK, prime minister Boris John- certain policies. belittles talents and hobbies that have taken son initially shook hands with hospital- decades to master. A scientist may, in their ized COVID-19 patients, then prioritized Putting yourself out there eyes, then transform from a boring person economics over health, overlooked mem- Scientists are trained over many years to who sits behind a computer all day to some- bers of his government breaching COVID sift through jargon and data to establish one who does science but also runs ultra- laws and changed his mind haphazardly facts, spot flaws and – mostly – set aside marathons or produces their own music. regarding education, free school meals their personal convictions should evidence Demonstrating that science is accessi- and Christmas celebrations. When scien- deem them unlikely. After all, even Einstein ble for anybody and everybody is not just tists extensively modelled the outcomes for could not fault quantum mechanics despite about improving the image of scientists. It COVID and detailed the steps required to his deep, philosophical trouble with the the- is also a pivotal step in dousing the anti- prevent the worst, a compliant government ory. Scientists are approached with complex science fire and drowning out conspiracies should have listened. Banging pots and and detailed situations sometimes falling – both vital if we are to continue the global pans for under-funded, over-worked NHS beyond the scope of their field. As people advance towards a more peaceful, safe and and other stressed keyworkers is not the seek to find a balanced view of hyperbolized healthy future. answer. And in the US we’ve seen a similar news, scientists appear a good first point of COVID rebellion, with its former president contact for their trained critical thinking. Caitlin Duffy is a contributing Donald Trump calling for protests against Although rewarding, being the fact- columnist for Physics World and is mask-wearing and lockdowns, as well as finding, jargon-juggling rock of reason is a PhD student at the High Field promoting the ingestion of bleach and often taxing as it not only requires time and Magnet Lab in Nijmegen, hydroxychloroquine, giving false statistics effort but mental gymnastics to produce a Netherlands, e-mail caitlin.duffy@ and highlighting vaccine cynicism. Thank- satisfactory response. Being the go-to for ru.nl

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com Comment: James McKenzie Transactions Grounds for optimism

The solution to climate change

could be lying beneath our feet. iStock/ttsz James McKenzie examines the potential of pumps that warm our homes and offices by extracting heat from the ground below About 15 years ago I bought a house in Cornwall. It wasn’t any ordinary house but a “future-technology” building that had been fitted with a ground-source heat pump and underfloor heating. It was a fan- Green and clean Ground-source heat pumps are an environmentally friendly way to warm our homes. tastic place to live in – well insulated and always cosy. As soon as my family moved in tion” envisages 600 000 heat pumps being dioxide-producing fossil fuel, is currently and we had unpacked, I simply had to find installed in Britain every year by 2028. so cheap. out how it all worked. That’ll save the equivalent of 71 million And there’s the rub. People are generally Built in 2001, the house had been fitted tonnes of carbon-dioxide emissions (16% poor at making long-term decisions based with a “GeoKitten” ground-source heat of the country’s total). on a potential future payback. If it’s a choice pump made by a local Truro-based firm First developed in the 1940s by an between saving money now or in the future, called Kensa, which pioneered the adoption American inventor called Robert C Web- most of us can only think of the here-and- of the technology in the UK. The pump is a ber after a bizarre incident in which he now. And unless customers want to pay extra bit like a fridge that works in reverse, pull- burned his hand on the hot outlet pipe for environmentally friendly systems, house ing heat in from liquid circulating through from his domestic deep freezer, there are builders have no reason to invest in them. coils buried underneath my front garden. now countless ground-source heat pumps That’s why new regulations, such as those Coupled to the underfloor heating circuit, around the world. Study after study has outlined in the UK’s 10-point plan, are so the pump made the house a fabulous place shown that such systems are both effective vital. They will force the construction indus- to live in, especially when winter storms and efficient. The reason why they’re not try towards this green technology. were raging outside in Falmouth Bay. the number-one choice for heating build- Lovely warmth was sent by the pump ings is simple: the up-front costs are high. Zeroing in around the house, with every room having A conventional domestic gas boiler uses The beauty of ground-source heat pumps is an adjustable flow rate and therefore pre- about 20 kW of power and costs £50 per that they can be fitted even in built-up areas cise temperature control. But as it was the kilowatt, whereas a comparable ground- where space is at a premium. A great exam- only form of heating, I was expecting a mas- source of 17 kW costs more like £500/kW. ple is the new headquarters of the Institute sive electricity bill. Turns out heat pumps Of course, if your house is well insulated of Physics (IOP) in King’s Cross, London. It are incredibly efficient, with the coefficient you need less capacity. Costs will also fall won a CIBSE building-performance award of performance (COP) – the ratio of heat over time as demand for such heating sys- in 2020 for its green technology, which output to electrical-energy input – being tems increases (regulation will be vital for includes photovoltaics, LED lights and an about 3–4.5. My fears were unfounded. that to happen). I suspect that the even- advanced ground-source heat pump consist- In fact, Kensa has been a great UK suc- tual mature market price of ground-source ing of 10 vertical boreholes extending 60 m cess story. Founded in 1999 by two for- heat pumps will be around the £100– below the building – the first time such a mer marine engineers who’d spent years £200/kW mark. system has been used anywhere in the UK. installing heat pumps on luxury yachts in That’s roughly similar to the cost of air- After its first full year of operation, the the Mediterranean, the company’s prod- source heat pumps, which transfer heat system had a COP rating of 3.4 – a figure ucts are now used in many domestic and from the outside air to the inside of a build- that’s likely to improve still further as the commercial settings. Realizing they were ing and are likely to be the main competi- system gets tweaked and optimized. It’s a local, I once called the owners, who kindly tor to ground-source pumps if gas boilers success story for the IOP, proving that the showed me round their factory. It was small are banned. Ground-source heat pumps physics community is leading by example back then, but the firm has grown and are harder to install. Installing the coils (or (bit.ly/2MYM77e). I believe green technol- expanded. David Cameron even visited in “slinkies”) in the ground has to be carefully ogy and growth go hand in hand, and that, 2009 before becoming prime minister. done. You also need to dig quite a few large with sufficient focus, the UK can meet its holes, which is tricky for anything other net-zero-carbon goal by 2050. Thanks in part Too hot to handle than a new or refurbished property. to heat pumps, we have the means to tackle Ground-source heat pumps are a great But if your house is well insulated, as the threat of climate change, which is one of way of heating. Apart from being quiet and it should be, then you can expect to save the most enduring dangers that we face. cheap to run, they need little maintenance money compared to an LPG boiler within and last for ages. Heat pumps will help seven years. Unfortunately, compared to James McKenzie was vice-president for business the shift away from traditional gas- and a mains-gas system, there’s no payback at at the Institute of Physics 2016–2020, e-mail oil-fired boilers – in fact, the UK’s recent all over that time with a ground-source [email protected]. He is writing here in a 10-point plan for a “green industrial revolu- heat pump. Gas, despite being a carbon- personal capacity

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com Comment: Robert P Crease Critical Point Beneath the rotunda

Robert P Crease reflects on dressed as mushroom clouds and skel- etons, while pro-science groups also have the US Capitol’s invasion from slogans and symbols. The Capitol’s invad- a unique perspective ers shared a mix of anger and celebration. Some painted their faces in patriotic red,

Architectwhite of the Capitol and blue and dressed as bald eagles If you stand in the Great Rotunda in the or revolutionary war figures, while others neoclassical US Capitol Building and carried iconography of racism and antisem- look up, you’ll see high above a concave itism such as Confederate flags. fresco entitled The Apotheosis of Wash- The three Cs reinforce each other in a way ington. Painted in 1865 by the Greek–Ital- that makes them propagate easily. Wouldn’t ian artist Constantino Brumidi, it shows it be great if you didn’t need to investigate the first US president surrounded by six complex issues involving your health and allegorical scenes. The details are hard to welfare? Which would you rather watch: a make out from 50 m below, but with bin- parade of invaders smashing the halls of gov- oculars – or Google – you can spot George Clear picture The Apotheosis of Washington in the ernment, or broadcasts of a legislative ses- Washington gesturing towards a scene US Capitol links democracy and science. sion or scientific conference? Don’t you wish representing science. truth and moral clarity were easier? The central figure in that particular were stolen,” say believers of the first story; Grand stories aim to spread enough scene is the Greek goddess Athena. Neither “Scientific evidence against my view was distrust so that the most persuasively and looks at the other; Washington has other faked,” say believers of the other. Alterna- vividly presented position seems the truest. things on his mind, while Athena is teach- tive “experts” are found to reassure believ- This is why commonly suggested antidotes ing people – including Benjamin Franklin, ers. The Capitol invaders, for instance, such as “better communication”, “science Samuel Morse and the steamboat pioneer swear by certain disaffected politicians, literacy” or “more dialogue” are ineffec- Robert Fulton – about a spark gap. Bru- while science deniers turn to the likes of tive; the messier and more difficult truth is midi knew that Washington, like America’s Bjørn Lomborg (for his views on climate harder to explain. other founding figures, believed in an asso- change), Peter Duesberg (AIDS) and Democracies have ways of tolerating ciation between effective democratic insti- Andrew Wakefield (anti-vaccination). grand stories without suppressing them or tutions and science. If contrary evidence persists, the reason letting their members dominate headlines, I thought of Brumidi’s fresco on 6 Janu- must be a conspiracy – an organized effort affect decisions or invade buildings. These ary this year as I watched live TV footage to produce falsehoods. In one grand story, ways involve a sifting process in which of domestic terrorists in the Great Rotunda the conspirators are socialists, political experts and institutions exercise judgment assaulting police, smashing artefacts and opponents, those of other races, and the by weighing evidence, consulting experts splashing blood on a sculpture (Brumidi’s “deep state”; in the other, foreigners and and repeated inquiry. This is not elitism, painting, high up in the oculus of the dome, the medical and scientific establishment. but democracy trying to make itself work. was unharmed). The carnage was incited Conspiracies explain contradictory evi- In the US at least, this process broke down by leaders who (amplified by social media) dence and strengthen buffers against it. well before 6 January. There’s a long-term were warring against both democratic insti- The trouble with conspiracies is that danger if we allow grand storytelling to tutions and science. I wondered about the they’re non-falsifiable, because any evi- metastasize in social life and become nor- connection between the two wars. dence against them is dismissed as manu- malized in politics, disconnecting beliefs factured by the conspirators. Conspiracies from reality and blurring the distinction The three Cs are also comforting, as they tell believers between fact and fiction. Each war is associated with a “grand story”. that the truth is not difficult and that they The grand story of the war on democracy is already know what’s really happening. The critical point that the 2020 US presidential election was Believe in a conspiracy theory and you I have no idea what George Washington fraudulent; the grand story for science is don’t need to understand, say, climatology, and Athena would have thought about the that evidence for things like climate change, epidemiology, demographics, physics or rampage taking place beneath them. The the pandemic and vaccines is false. Each voting machine technology. kind of battle occurring was not one each story provides justifications for rejecting The third element bolstering grand sto- had to fight. To keep it from recurring contrary evidence, with the key elements ries is that they make believers feel spir- will involve rebuilding trust and creating being that the evidence has been faked, that itually and morally uplifted. Grand stories an even grander and still more uplifting a group of people plotted that fakery, and provide an apparent moral clarity, divid- story whose key elements are periodi- that attacking it is moral and just. I think of ing the world into a blameless “us” and a cally rechecked facts, discerningly chosen these elements as the “three Cs”: convic- wicked “them”, with the former represent- experts, respect for irritations of doubt, tion, conspiracy and community. ing the community as a whole and the latter and messier truth and moral vision. This is Let’s start with the first C, that adher- a malevolent minority. To keep the group painstaking, frustrating and never-ending ents are firmly convinced of their beliefs. from splintering into sub-tribes with differ- work, but the price of effective democracy. Such convictions insulate belief against the ent views and aims, grand stories maintain doubt that might inspire need for further unity through pageantry and entertain- Robert P Crease is chair of the Department inquiry; contrary evidence must be wrong ment. I’ve seen anti-nuclear protests of Philosophy, Stony Brook University, US, or was manipulated. against research reactors that were picnics, www.robertpcrease.com, e-mail “If my friends lose the election, ballots with folk singers and dancers and people [email protected]

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 physicsworld.com REVISITING ELECTROMAGNETIC Contents In the first part aimed at school pupils, the book can also PHENOMENA: of the book John be used as a resource in higher education. shows that the Last year, I made a YouTube video Ritz hypothesis is Introducing the Radiated Electrical Property: Feedback Newell Jordan explaining the theory of elasticity using consistent with the my hair as an example (bit.ly/3aYWvnR), Amended & Extended Edition various experiments that make up the Letters and comments that appear here may have showing how this concept was an field of relativistic been edited, and do not necessarily reflect the views extension of myself and those who might Author: John Purssell Ballad optics. During these of Physics World. look like me. So rather than starting studies he has the conversation with physics, I began Published: Hillcroft Publications, Sept 2020 stumbled upon what Please send us your feedback by e-mail to by talking about something (hair) that ISBN 978-0-9557502-1-2 he believes to be [email protected] everyone can relate to – whether you have a decisive test for hair of my texture or not. the Ritz hypothesis. I don’t expect all of physics to be Hardback; 384 pages; 165 mm x 243 mm x 30 mm. Beyond John’s Breaking down barriers made quite so approachable as it is a means, this test very complex subject that takes time to 800 gm; 78 Figs, 37 Tables, Numerous Equations remains undone. In response to the careers article “On the road less understand fully. But I do hope that the He then introduces travelled” (December 2020 pp45–46), in which physics community will make the effort to the Radiated Tamia Williams from Pace University in New York Open for all Tamia Williams is keen for physics to be bring us closer to equity and inclusivity. Price: £40 plus p&p Electrical Property discusses her experiences as a Black physicist. more inclusive. (REP) and using simple models shows that linear and accelerated relative motions of source and receiver give Copies may be obtained from the author rise to the main laws of electromagnetics. Then, whilst Williams describes some of the difficulties Tamia Williams replies: Deep thinkers needed considering electron motion under a central force, he finds that Black people experience getting As a child, I loved science. It gave me the Contact: [email protected] that applying the Ritz consequences to this situation gives into – and then succeeding in – physics. ability to explore, connect and make sense In response to the Forum article “Why breadth beats rise to a non-zero tangential force component. Solution of In particular, she says that “the culture, of the natural world around me. Science depth” (January p19), in which physics teacher Niki the resulting equations of motion revealed the existence vernacular and coursework of physics was approachable because it lived in my Bell argues that subject-matter specialists don’t Thought that there is nothing new to discover? of relatively non-radiating circular states, thus indicating disregard the vocabulary and syntax used head without biases. This feeling stayed necessarily make the best teachers. a possible link with quantum mechanics. Finally, after throughout the Black community”. with me until I was an undergraduate Read this book to find out more reviewing the whole gamut of sources of EM radiation, It is in all our interests to promote pursuing higher level physics. Then the The crux of the article is the observation . he concludes the book by exploring whether shielding of physics as widely as possible, and to curriculum and coursework reached a that, for physics teachers, “the better they emitted REP at the nuclear level could provide a possible remove barriers that deter people or hold point where I felt inadequate learning know the subject, the harder they find Suitable for degree and postgrad readers. explanation of gravitational attraction. them back. We need to address issues like the subject. Luckily, I had professors communicating it to students”. this, but to do so we need to understand who seemed to understand the barriers First, this observation goes against the them. Think about the “language” of that come with learning the subject findings in the literature. The evidence physics, which is by nature different from and provided spaces for me to feel shows that teachers with greater subject- the language of everyday life. We know welcomed regardless of those barriers. specific expertise provide better outcomes popular misunderstanding of scientific Some professors, for example, offered for students, both in terms of their principles is widespread, in part because extended office hours or weekly or attainment and the likelihood of them everyday language is imprecise and biweekly one-on-one meetings with me, choosing physics beyond 16. This evidence Astronomy and ambiguous. But where everyday language and they always sent me potential research is discussed in the recent Subjects Matter in the Black community differs from the opportunities aligned with my interests. report from the Institute of Physics (bit. language of the majority (for want of a I am aware that these methods might not ly/2MNEh0T). MCA Base astrophysics better expression), there’s a greater gulf be as conducive at a larger institution, Second, the statement and article to bridge. but there are still other ways to engage play on harmful stereotypes of physics The MCA51CP is a compact Multichannel Analyser designed for Find the information you need from IOP Publishing’s So how can we make our scientific with your students, such as sending out a and physicists. It may well be true that gamma-ray spectroscopy applications with NaI(Tl) scintillation world-leading journals and award-winning books language and culture more inclusive? get-to-know-you survey or a five-minute not all excellent physicists are cut out detectors. The base houses an integrated high voltage power programme, along with conference proceedings and What do we need to change in, say, our “mood meter” check-in before the start for teaching. But we should be very coursework or curricula? People like me of a new lesson. I believe any activity that wary of generalizing that statement into supply and uses powerful digital signal processing to provide a science news from Physics World. (old, white, male) need help to see the shows that you have a bit of humanity can a form that suggest all physicists are Multichannel Analyser with a USB interface. problem from the perspective of those who go a long way for our Black students and poor communicators. iopscience.org/astronomy-and-astrophysics suffer from this problem; we need help to students of colour. As well as doing a disservice to a identify how to change our behaviour and There is no magic formula for making number of great physics communicators, to find better ways of communicating. physics and its language more inclusive. such generalizations harm the discipline Physics World should expand on this We can, however, look to become more because they deter excellent potential theme in future issues. Examples – both culturally responsive in our teaching, teachers by reinforcing a mythical good and bad – always help. After all, it’s coursework or curricula – whether by version of physics that is off-putting to surprising how much ingrained behaviour acknowledging our biases, creating young people.

1.2 can be shown up by reference to real- deeper academic relationships with Teachers of physics need a deep and 1 s t

n life illustrations. And we could look for Black students or students of colour, or broad insight into the discipline – its

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e 0.6 successful “cultural changes” to inspire connecting content to relevant examples ideas, its explanations and its ways of l i z a

r m 0.4 o us. Working in automotive engineering, that reflect those students’ lives. thinking – in order to establish firm N 0.2 I’ve seen a sustained approach to One great place to start is Zarretta foundations of subject knowledge through 0 0 200 400 600 800 1000 1200 Channel Number inclusivity that has brought great benefits Hammond’s 2015 book Culturally a compelling and clear narrative. Their to the work environment. Responsive Teaching and the Brain (bit. ability to communicate that narrative Contact us for details on our range of photomultipliers and electronics Let’s be part of the solution, not part of ly/3abxWVJ), which looks at how to is what inspires students to fall in love the problem. engage with students from culturally and with physics. Julian Philpot linguistically diverse backgrounds and Charles Tracy www.et-enterprises.com Macclesfield, UK can provide a better understanding of Head of education, Institute of Physics, London, UK [email protected] inclusivity in the classroom. Although it is [email protected]

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SUPERCON, Inc. prediction of universal gravitation came Against short-termism Predicting the long before it was observed in a controlled Superconducting Wire Products experiment. James Clerk Maxwell’s In response to Robert P Crease’s Critical Point article qualifies too as his prediction that time- Standard and Speciality designs are available to meet your most demanding “Very deep thinking” (February p18), which argues unexpected varying electromagnetic fields produce that looking thousands – or hundreds of thousands waves led to Heinrich Hertz’s unexpected superconductor requirements. – of years into the future is vital for humanity. In response to David Appell’s feature “The 10 demonstration of radio. Siméon-Denis greatest predictions in physics” (January pp36–40). Poisson’s work on the “Arago spot” SUPERCON, Inc. has been producing niobium-based superconducting wires and cables for 58 years. Crease’s article truly resonated with (showing that light is a wave) and Fred We are the original SUPERCON – the world’s first commercial producer of niobium-alloy based wire and me. I have long been railing against the The top 10 theoretical predictions that Hoyle’s prediction of the 7.65 MeV energy cable for superconducting applications. short-termism associated with quarterly Appell picked are all worthy discoveries level in carbon-12 (vital for the existence business reports, three- or four-year of fundamental importance, but it would of life) also meet my criteria. election cycles and politicians who, have been more interesting to limit his But one of Appell’s choices – the Standard SC Wire Types Product Applications in their desire to get back into power, choices to predictions that were totally Josephson effect – surely doesn’t fit NbTi Wires Magnetic Resonance Imaging only consider immediate problems unexpected and can be described, as the bill. It predicted that Cooper pairs Nb3Sn —Bronze Nuclear Magnetic Resonance and ideas. Crease, however, clearly patent lawyers would say, as “not obvious of electrons would tunnel through underlined the desperate need for some to someone skilled in the art”. In addition, an insulating barrier between two Nb3Sn —Internal Tin High Energy Physics even-longer-term thinking. the predictions should have included superconductors, but Leo Esaki had CuNi resistive matrix wires SC Magnetic Energy Storage The climate is one obvious current something specific that was unknown already invented the tunnel diode in 1957. Fine diameter SC Wires Medical Therapeutic Devices example where long-termism is needed. to science at the time and was only later As for dark matter being in the top 10, it’s Aluminum clad wire Superconducting Magnets and Coils So is nuclear energy, which will surely be confirmed by observation. currently not a prediction but a deduction necessary to wean us off carbon-based Predictions that meet these criteria, from observation, despite there being Wire-in-Channel Crystal Growth Magnets petroleum. Renewables are all well and but which Appell didn’t mention, include nothing more fundamentally important or Innovative composite wires Scientific Projects good, but we don’t have the time to wait Albert Einstein and Karl Schwartzschild’s upsetting to current knowledge. until they will be fully available. What a singularities (black holes), Paul Dirac’s Stan Rosenbaum dilemma and, ageing and aged as I am, I positive electrons (antimatter), Hideki Edmonton, Canada shan’t be here to watch the outcome. But Yukawa’s mesons (pions and the [email protected] “We deliver when you need us!” my grandchildren will be – and that is, of Standard Model of particular physics), course, a great concern. and Ralph Alpher’s cosmic microwave It may seem a quibble, but surely Appell www.SUPERCON-WIRE.com David Wolfe background radiation. is mistaken in his use of the word London, UK Of Appell’s chosen 10, I’d say Isaac “prediction” in most of his examples? Is it [email protected] Newton easily qualifies because his too much to demand that a “prediction”

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To find out more about the journal scope and how to submit your paper, please visit iopscience.org/nce or e-mail [email protected]. Feedback physicsworld.com Hexapod-like must precede the discovery? Einstein was scientific hypotheses. justifiably excited by his explanation of the The final word on Tim Palmer makes an interesting point precession of the perihelion of Mercury, about counterfactuals, albeit tangential but he did not predict it – he knew about to the issue my article addressed. As it already. What he did predict, however, free will? for Sabine Hossenfelder, she seems to SMARPOD was the amount by which light would be want us to stop talking about “free will” With user-definable pivot point and force feedback micro-gripper. bent by the Sun, and when that was borne In response to a series of letters (February p21) at all. But volitional decision-making out in 1919 he became world famous. about the Forum article by Philip Ball titled “Why free is a neurobiological fact, and is being In the cut-throat world of theoretical will is beyond physics” (January p17). fruitfully explored as such – a better physics, a genuine prediction carries extra approach than sterile philosophical • Wide range of high-precision weight compared with a mere explanation, I anticipated that some physicists might debates about determinism. That “the positioning solutions because the latter is like solving a be upset with my suggestion that their future is determined by the present, up to homework problem when the answer is in discipline does not have the final word quantum random events” is not in doubt – • Complex motion control in 6 the back of the book. One can keep tuning on “free will”, but I had hoped they and not the issue. Insofar as Hossenfelder DoF with nanometer resolution one’s calculation until arriving at the right might offer arguments rather than wants free will expunged from physics, I’m answer, and then one stops. mere grumpiness. To start with Alan pleased to note we agree. • Simple integration into existing Of the items on Appell’s list, I vote Calverd, I am not sure what point he is To sustain any notion of what has setups for the prediction of parity violation by trying to make. Yes, physics is not fully traditionally (and misleadingly) been Tsung-Dao Lee and Chen-Ning Yang deterministic – I said as much. The called free will, it is enough to be able • Easy to combine with various as number one, because it predicted fact that different organisms behave to say that our brain processes are the SmarAct micro-grippers something that most physicists at the differently under similar circumstances cause of our decisions and actions. There • Tailored design for your time thought impossible a priori. I also tells us nothing about free will, being in is a well-established literature on why, in applaud Appell’s choice of the prediction itself consistent both with its presence and complex systems, such causation may not micro-assembly task of dark matter by Vera Rubin and Kent its absence. be the mere sum of many tiny “causes” Ford, because dark matter has not yet John Allison’s assertions, meanwhile, flowing up from the atomic scale. The been found. So not only did Rubin and are unsubstantiated. Because the neurobiology of decision-making is now Ford predict it, but Appell himself is in a suggestion by Brian Greene that any a mature enterprise, which it would be way making a prediction by putting it on action we take was predetermined by hubristic and wrong to regard as a kind of the list. physics is both untestable and silent about renormalized physics. Alan Chodos causation, it is metaphysical. Exploring Philip Ball University of Texas at Arlington, US decision-making through neurobiology, London, UK [email protected] however, creates testable, truly [email protected] Clean-Critical Fastener & Seal Solutions HV, UHV, EUV, Cleanroom Ready Fasteners and Seals in Just About Any Size, Material, and Finish to Meet Your Needs!

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Digging up magnetic clues Analysing magnetic information stored in ancient artefacts is revealing the recent history of the Earth’s magnetic field and providing clues to the changes we might expect in the future. Rachel Brazil explains

The idea that a record of the Earth’s magnetic past We already know that the Earth‘s magnetic field Rachel Brazil is a might be stored in objects made from fired clay dates has lost around 10% of its intensity over the last science writer based back to the 16th century. William Gilbert, physi- 150 years. “The dipole strength has been steadily in London, UK, cian to Queen Elizabeth I, hypothesized in his work decreasing at a rate such that, should it continue, Twitter De Magnete that the Earth is a giant bar magnet and in 2000 years the magnetic field strength would be @rachelbbrazil that clay bricks possess a magnetic memory. This zero,” says geologist Rory Cottrell of the University phenomenon – known as “thermoremanent magneti- of Rochester in the US. “The thought is that the zation” – now forms the basis of a well-established planet is headed for a magnetic field reversal.” method for dating archaeological sites that contain Data collected from magnetic records in rocks kilns, hearths, ovens or furnaces. indicate that over the last 76 million years there Indeed, the study of these burnt materials con- have been 170 reversals in which the north–south taining magnetic minerals, found at archaeological polarity of the field has completely switched. And www.ipac21.org sites, is known as “archaeomagnetism”. One of the it seems that another event is overdue: a full rever- aims of this field is to help geophysicists gain a better sal has happened, on average, every 200 000 years understanding of local changes that have occurred in over the last 10 million years, and the last one was the Earth’s magnetic field over the past 3000 years. 780 000 years ago. And if we know how the field changed in the past, Even small changes in the Earth’s magnetic field we could also get insights into our magnetic future. can have far-reaching repercussions for the planet’s

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1 Strange anomaly 2 The Earth’s magnetic field a b magnetic north geographic east geographic north Shutterstock/Milagli inclination declination

field direction Division of Geomagnetism, DTU Space

down

a The Earth’s magnetic field acts like a giant bar magnet, with the field lines encircling the planet and protecting it from the solar wind. b The direction of the magnetic field at any given point on the Earth’s surface is defined by the declination – the angle on a horizontal plane between magnetic north and the North Pole. This angle varies across the Earth’s surface and changes over time, making it of interest to those involved in “archaeomagnetism”.

ing. “The job of the archaeomagnetist is to take sam­ even [the remains of] cities that burned down, make ples and measure them to death,” says Hare. an excellent archaeomagnetic record,” says Biggin. But obtaining accurate measurements is far from It is even harder to determine the magnetic inten­ The South Atlantic Anomaly is an area of weak magnetic field stretching from South America to southern Africa, captured here by the European Space Agency’s simple. For a start, the residual magnetism in archaeo­ sity from archaeological artefacts, since the present­ Swarm satellite constellation. The anomaly has been growing and intensifying over the last 200 years, which could mean that a reversal of the Earth’s magnetic logical samples is tiny, with magnetic moments in the day measurement also depends on the intrinsic field is on its way. To see if that might happen, geophysicists have been examining archaeological artefacts to try to decipher how our magnetic history has changed order of 10–3–10 –5 Am2/kg, which is an order of mag­ ability of the sample to acquire thermoremanent over the previous 3000 years. nitude lower than would be required to move a com­ magnetization. The easiest way to determine this pass needle. Such small magnetic signals can only intrinsic property, says Biggin, is to expose the sam­ surface. That’s because the magnetic field acts as a magnetic history. Unfortunately, direct observations be detected with cryogenic magnetometers made ple to a known magnetic field and then measure the shield, repelling and trapping charged particles from of the Earth’s magnetic field have only been collected from superconducting quantum interference devices resulting magnetization. If, for example, the new the Sun that would otherwise cause electrical grid since the 1850s, and even then only in some locations. (SQUIDs). Experiments must also be carried out in magnetization is twice as strong as the ancient mag­ failures, navigational system malfunctions, and sat- While magnetic information contained in rocks goes a “magnetic vacuum”, often using a Helmholtz cage netization, the ancient magnetic field must have been ellite breakdowns. Strong solar winds already cause back millions of years, researchers have focused their that creates a uniform magnetic field to cancel out half as strong as the controlled field used in the lab. problems from time to time, notably in 1989 when attention on archaeological artefacts to reconstruct the Earth’s magnetic field. But working with ancient pieces of clay inevitably a billion-tonne cloud of solar plasma breached the our magnetic history over the last 3000 years or so. Another complication is the compound nature introduces problems, partly because the heating pro­ Earth’s magnetic field. This created electrical cur- The field of archaeomagnetism relies on the fact of the raw magnetic signal. “The measurements cess often causes chemical changes or physical dete­ rents in the ground that caused an electrical power that clays or other materials containing magnetic are often a vector sum of the ancient magnetiza­ rioration in the samples. “I have never encountered blackout across the entire province of Quebec, Can- minerals – usually magnetite – lose any magnetic tion you’re interested in, and also more recent over­ an analytical technique that is so difficult and takes ada. If the field weakens further, we can expect more ordering when they are heated to above 570 °C (the prints,” says Andy Biggin, a palaeomagnetist at the so long,” says Hare. “You can get a month into your such events, triggering major disruptions. Curie temperature). Indeed, the sample loses its net University of Liverpool in the UK. Those more measurements, and then have them fail.” Clays or other A particular cause for concern is the South Atlan- magnetization but when it cools back down below recent or “secondary” magnetizations, he says, can Despite these difficulties, geophysicists have materials tic Anomaly, an area stretching from Chile in South the Curie temperature, the particles remagnetize often be successfully removed by incrementally heat­ already pieced together an accurate magnetic record containing America to Zimbabwe in Africa, where the magnetic in the direction of the local magnetic field at that ing the samples to temperatures approaching the for western Europe and large parts of the Middle magnetic field intensity is much lower than the global aver- time. In this way, these archeological samples pro- Curie point, and then cooling them down after each East. In the UK, for example, archaeomagnetic dat­ age (figure 1). The magnetic field strength across vide a snapshot of the Earth’s ambient magnetic field heating step. “That gradually strips away the less sta­ ing now extends back to 1000 BCE, in some cases minerals lose this region can reach as low as 25 µT, compared through different times and places in history. These ble magnetizations,” Biggin adds. with accuracies within tens of years. any magnetic with up to 67 µT for other parts of the Earth’s sur- samples can reveal both the intensity of the magnetic The accuracy of the measurements also depends ordering face. “It’s low enough that incoming radiation is no field and its direction, which is measured at any point on the magnetic structure of the sample, with smaller Searching for anomalies when they are longer deflected and it interferes with satellite trans- on the Earth’s surface by the declination – the angle magnetic grains retaining their magnetization for This increasing amount of archaeomagnetic data heated above missions,” says Vincent Hare, a geophysicist and on the horizontal plane between magnetic north and longer. In magnetite, for example, magnetic grains suggests that the current South Atlantic Anomaly archaeological scientist at the University of Cape true north (figure 2). measuring 50–80 nm can store their magnetic infor­ is not the only example of extreme local variations 570 °C, but Town, South Africa. What’s more, the anomaly has The first attempt to extract magnetic information mation for billions of years. Obviously, accurate in the recent history of the Earth’s magnetic field. then become been growing and intensifying over the last 200 years from fired clay was made in the late 19th century, readings of the field direction can only be taken if One area of focus is the Middle East, where a team imprinted with or so, which could be yet another signal that a field when the Italian scientist Giuseppe Folgheraiter the object has not been disturbed since the field was of geologists and archaeologists has been study­ the Earth’s reversal is on its way. calibrated a “geomagnetic secular variation curve” imprinted. In other words, the materials should not, ing the magnetization of ancient artefacts found in ambient – a record of changes in both the declination and for example, have been significantly dried or water­ Israel. “We found very mysterious magnetic fields magnetic field Measuring archaeomagnetism inclination of the Earth’s magnetic field, in a given logged since the sample was last heated to the Curie and surprisingly different than expected – super To understand whether this localized anomaly might location – for dating ancient pottery. The technique temperature. This requirement rules out a number super strong,” says geophysicist Ron Shaar from the when they are be a sign of more significant changes, geophysicists became more established in the 1970s, and can now of types of samples including those that may have Hebrew University of Jerusalem. Strange behaviour cooled have been examining our planet’s relatively recent deliver the same sort of precision as radiocarbon dat- been disturbed while being found. “Pottery kilns, or was seen in the field direction as well as the intensity,

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3 Hidden meaning between today and 1500 CE, the rate of change was on the order of 0.06° per year, but between 1500 CE A new measurement technique being and 1350 CE, it was almost double that,” explains Cottrell. The team also identified an earlier period developed combines computed of relatively rapid change between the 6th and 7th centuries CE. X-ray tomography with scanning

Megiddo Expedition Megiddo Expedition Megiddo Cottrell believes that this variability is the most recent historic display of whatever phenomenon is magnetometry causing the current South Atlantic Anomaly. This had previously been thought to be only a very recent event, but these new findings suggest that some parts of the world might to be prone to repeated changes in the magnetic field. To test this idea, Biggin looked further back in the geological record. He studied Shaar. “There is nothing to worry about based on volcanic glasses formed 8–11.5 million years ago comparison of today’s field with what we know about on the island of Saint Helena, right in the middle the ancient field.” That view is backed up by mag- of the South Atlantic Ocean, and also found large netic records obtained from rocks that were formed variations in the direction of the magnetic field. This much further back in the Earth’s history, which show finding therefore supported the view that the Earth’s that the Earth’s magnetic field is now globally much magnetic field has been unstable in this region for stronger than in the 50 000 years leading up to the millions of years. past five reversals. Despite this general reassurance, there is still a The hill-top site of Tel Megiddo in Israel contains the remains of at least 20 cities, dating from about 5000 BCE to the 4th century BCE. Artefacts recovered from the site have revealed significant anomalies in the Earth’s magnetic field going back to the Iron Age. Among those to have worked on the project have been geophysicist Under the mantle lot to explore and understand about the anomalies Ron Shaar from the Hebrew University of Jerusalem and archaeologist Israel Finkelstein. It is still unclear why certain regions experience these in the Earth’s magnetic field. That means collecting continuing anomalies, but geophysicists believe that more data on intensity variations over the last three the answer may lie in the interactions between the millennia, but that’s a daunting task when there is with anomalies of more than 10° from the prevailing August 586 BCE. Their results reveal similar high- Earth’s mantle and its outer core, the 2889 km layer still such a high failure rate in sample analysis. “Very field direction of the time. field values, and also provide an exact anchor date of molten iron-rich rock that is responsible for the few [geophysicists] focus on intensity, because the In 2016 the team published results obtained from for their measurements (PLOS ONE 15 e0237029). Earth’s magnetic field. The magnetic field is gen- experiments drive them mad,” says Hare. “But it’s pottery shards and cooking ovens found at Tel Data from further afield show just how far the erated by a dynamo process in which the Earth’s the key to this whole question.” Megiddo and Tel Hazor, two sites in Israel that were anomaly stretched at that time. “We can trace its evo- rotation, combined with convection currents in the One solution could be a new measurement tech- occupied during the Iron Age more than 3000 years lution, how it starts in the Middle East and migrates molten core, creates rotating columns of liquid that nique being developed by Lennart de Groot, a ago (figure 3). The data reveal the evolution of an westward toward western Europe over a period of a generate the magnetic field. “When you move a con- geophysicist from Utrecht University in the Neth- extreme geomagnetic high between the 11th and 8th few hundred years or so,” says Shaar. He and others ductor through a magnetic field, you induce electric erlands. Rather than simultaneously measuring the centuries BCE, culminating in two “archaeomag- have studied material from Turkey and Cyprus that currents and that makes more magnetic field – so it’s magnetism of millions of grains in one sample, de netic jerks” or “geomagnetic spikes” where the field show large swings in magnetic field direction from self-sustaining,” explains Biggin. Groot combines computed X-ray tomography with intensity shoots up and down again in less than a cen- 1910 to 1850 BCE, with exceptionally high intensities Anomalies in the magnetic field are thought to scanning magnetometry to calculate the unique con- tury (Earth and Planetary Science Letters 442 173). around 700 BCE. Other data from Georgia showed be associated with patches of magnetic field in the tribution of each grain (Geophysical Research Letters The two spikes are centred at 732 BCE and 980 BCE, high-field values in periods stretching from the 10th outer core that are stronger or weaker relative to 45 2995). More accurate results can be achieved, he and each one has a field strength more than twice to 9th centuries BCE, as well as fast-field variations the overall magnetic dipole, or that even point in says, because the technique requires only a small that of the current dipole field. This period has since about 500 years later. the opposite direction. “As these flux patches move, subset of the magnetic grains contained within become known as the Levantine Iron Age Anomaly. But this unusual magnetic behaviour is quite dif- they intensify and diminish, and cause very fast local each sample. One intriguing possibility is that the effects of ferent from the anomaly now seen in the southern changes,” says Biggin. Indeed, the current South It will also be important to source samples from a these high fields might have been seen during bibli- Atlantic, which is a localized region of weak magnetic Atlantic Anomaly seems to sit on top of one or more wider variety of locations. Detailed magnetic profiles cal times. Passages from the book of Ezekiel, writ- field. To find examples of similar low-intensity anom- patches of opposing flux. now exist for Europe and much of the Middle East, ten 2600 years ago and chronicling a journey through alies from the past, Cottrell decided to search for The Rochester team has proposed that these flux while data coverage in China is also improving. It Turkey, describe an immense cloud with flashing clues in southern Africa. Working in collaboration patches are associated with temperature or density remains difficult to source magnetic data from the lightning surrounded by brilliant light. This depic- with South African archaeologists, Cottrell identi- changes deep in the Earth’s mantle. “Africa sits on southern hemisphere, but Cottrell is continuing her tion is thought to refer to the Aurora Borealis, nor- fied suitable samples from sites near the Shashe and top of a very special seismological feature in the inte- work in Africa, adding that “there has been a con- mally only observed in the far north when charged Limpopo rivers in northern South Africa, Mozam- rior of the Earth, called a large low-shear-velocity certed effort by many researchers, particularly from particles collide at high speed with the stronger mag- bique, Botswana and Zimbabwe, dated from 425 to province,” says Hare. “It’s essentially a slightly heav- South America, to collect this data”. netic field in these regions. But a stronger magnetic 1550 CE. ier portion of the lowermost mantle of the Earth that As more data become available, geophysicists field over the Middle East at that time could explain “The Iron Age of southern Africa is a good place sits on top of the outer core, and protrudes slightly are convinced that more anomalous behaviour will the lights seen by the prophet. Although the time to go,” says Hare, who was part of the study team. into it.” This protrusion then perturbs the flow of the emerge in the Earth’s magnetic history. There is period doesn’t match exactly with the spikes detected He explains that the local people would have built liquid outer core, causing flux patches that alter the already some evidence of strong flux patches under by the team, geologist Amotz Agnon – a colleague of huts with clay floors, and regularly performed cer- magnetic field on the Earth’s surface. Siberia, for example, and in the Southern Ocean Shaar in Jerusalem – points out that “with prophe- tain rituals to cleanse the community if there was near Australia. Shaar agrees that other anomalies cies, you never know, maybe [this was] just a rumour a drought or a similar event. “One of those would Future clues will be found, and predicts that any new discoveries from some oral tradition”. be the burning of a hut floor, and that’s perfect for Overall, the data from archaeomagnetic studies will be just as puzzling as those reported so far. “The In 2020 Shaar and his team published new data archaeomagnetism.” have been reassuring for the future of the Earth’s world is huge and I suspect that we will find in the from an Iron Age excavation site in Jerusalem. They So far only field-direction measurements have been magnetic field, since the anomalies we see today are future that the geomagnetic field is nothing like we analysed 397 samples of burnt material from the published, but these early results already show inter- clearly in line with past behaviour. “What we have have measured in the past few hundreds of years,” floor of a building that they deduced was destroyed esting anomalous behaviour (Geophysical Research observed over the past several hundred years is a very he says. “It is an evolving thing, constantly changing, during the Babylonian conquest of the city, dated to Letters 45 1361). “If we look at the magnetic field normal behaviour of the geomagnetic field,” says and there will be many surprises.” n

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A new generation takes on CollaborationDES the cosmological constant The long-standing problem of the cosmological constant, described both as “the worst prediction in the history of physics” and by Einstein as his “biggest blunder”, is being tackled with renewed vigour by today’s cosmologists. Rob Lea investigates

Rob Lea is a science The cosmological constant has been a thorn in the relativity (GR) seemed to suggest that the universe writer based in side of physicists for decades. Even though its pur- is contracting, thanks to the effects of gravity. The Liverpool, UK, Twitter pose in modern cosmology differs from its original consensus at the time was that the universe is static @sciencef1rst role, the constant – commonly represented by Λ and, despite having already revolutionized several – still presents a challenge for models designed to long-held ideas, Einstein was unwilling to challenge explain the expansion of the universe. this particular paradigm. This desire to preserve the Simply put, Λ describes the energy density of empty stability of the universe led Einstein to make an addi- space. One of the main issues stems from the fact tion to GR’s equations. Later, he would infamously that Λ’s theoretical value, obtained through quan- describe this as his “biggest blunder”. tum field theory (QFT), is nowhere near the value “When Einstein was applying GR to cosmology, he obtained from the study of type Ia supernovae and realized he could add a constant to his equations and the cosmic microwave background radiation (CMB) they would still be valid,” explains Peter Garnavich, a – in fact it diverges by as much as 10121. It is therefore cosmologist at the University of Notre Dame, France. of little wonder that cosmologists are eager to tackle “This ‘cosmological constant’ could be viewed in two this disparity. equivalent ways: as a curvature of space–time that “The cosmological constant problem, in one form was just a natural aspect of the universe; or as a fixed or another, is a century-old puzzle. It is one of the energy density throughout the universe.” biggest problems in modern physics,” says theoreti- Thus, the initial role of Λ was to counterbalance cal physicist Lucas Lombriser from the University the effects of gravity and help ensure a steady-state of Geneva (UNIGE), Switzerland. “Moreover, the universe that is neither expanding nor contract- cosmological constant is the most dominant compo- ing. This role, however, became obsolete following nent in our universe. It makes up 70% of the current Edwin Hubble’s discovery in 1929 that the universe energy budget. How could one not want to figure out is expanding. When Einstein was finally convinced what it really is?” of this, Λ was designated to the cosmic dustbin. Yet, Indeed, with a new generation of cosmologists now like the proverbial bad penny, it would resurface in a on the scene, there are some rather radical ideas and different form decades later. revisions of older theories. But can the field accept Whereas once the cosmological constant was used these revolutionary ideas, or has Λ become a com- to balance the universe against expansion, in modern fortably familiar burden? cosmology Λ represents vacuum energy – the inher- ent energy density of empty space – that no longer Still crazy after all these years just balances gravity , but overwhelms it. That doesn’t The cosmological constant was first introduced to mean Λ has become any less problematic, though. models of the universe by Albert Einstein in 1917. “In 1998 the High-Z Supernova Search team discov- To the physicist’s own surprise, his general theory of ered that the expansion rate was accelerating instead possible explanation for the dark energy that drives torio Astronómico Nacional, Universidad Nacional More than meets of decelerating,” says Garnavich, who took part in this accelerating expansion, and its theoretical value de Colombia, García is putting forward an “early the eye the research using type Ia supernovae to study the should therefore match observations. Unfortunately, dark energy” (EDE) model as a potential solution to The Dark Energy There are some radical ideas and expansion of the universe. This requires some form as mentioned, the former is greater than the latter by the cosmological constant problem (New Astronomy Survey uses the of additional energy throughout the universe or some 120 orders of magnitude. Clearly, Λ’s reputa- 84 101503). Victor M Blanco revisions of older theories. But can some more exotic explanation. This driving force tion as “the worst prediction in the history of phys- The radical element about the team’s proposal is telescope in Chile to investigate the large- is referred to as “dark energy”, and the term itself ics” isn’t mere hyperbole. the idea that cosmological models might not need scale structure of the the field accept these revolutionary has become a placeholder for the various theoreti- the cosmological constant at all. Of course, there universe. cal entities that could account for this accelerating Getting a head start on the problem is still that accelerating expansion to consider, so to theories, or has Λ become a expansion. Suspects range from vacuum energy, the The role of dark energy in the early universe has account for this, García looks to other sources. current most favoured model; to quantum fields; and been on the mind of Luz Ángela García, a physi- “When I first approached this field, I came across even fields of time-travelling tachyons – hypothetical cist and astronomer at Universidad ECCI, Bogotá, the inconsistency with the values predicted from comfortably familiar burden? particles that travel at faster-than-light speeds. Colombia. Together with her collaborators Leonardo both cosmology and high-energy physics, and tried The cosmological constant serves as the simplest Castañeda and Juan Manuel Tejeiro from Observa- to formulate an alternative model to Λ by studying

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1 A cosmic conundrum picture that matches the ratio we observe in the cur- 2 A type Ia supernova rent dark-energy-dominated epoch of our universe, where its matter/energy content is dominated by the accelerating force. “Of course, we could use both the cosmological constant and our EDE, but it makes the description unnecessarily complicated, and there Ann Feild (STScI) is not a physical justification for that,” says García. CC BY SA 4.0/ESO “We only need one component to describe the accel- present erated expansion of the universe today.” If the decision to eliminate the cosmological con- stant, or set it to zero, taken by García and her col- accelerating laborators seems somewhat arbitrary, she points out expansion

time that there is almost an “arbitrariness” inherent to farthest

15 billion years) the introduction of the constant in the first place.

~ slowing supernova ( expansion “There is no fundamental reason to take for granted that dark energy has to manifest as the cosmological Big Bang constant,” she remarks. “We have not detected any form of dark energy nor the cosmological constant; expanding universe therefore, any form of dark energy is valid until the data confirm or refute its existence.” The different eras of cosmic expansion. Dark energy dominates in the final era, driving accelerated expansion -- and this is characterized by the cosmological constant. However, The EDE that García suggests isn’t perfect. Indeed, “early dark-energy” models suggest that this element could have been present in the it comes with elements that the wider scientific com- earliest moments of the universe, albeit exerting little influence. munity may be reluctant to adopt. But she doesn’t shy away from pointing out the potential flaws in her own ideas. “There are two issues that the community possible candidates to explain the accelerated expan- could find troubling,”García admits. “On the one sion of the universe,” she says. hand, more complex models imply a broader set of Λ, as it is currently considered, only accounts for free parameters. It is not something we desire for our the universe’s expansion once matter began to form formulations, because those parameters might not structure – an era that lasted from 47 000 years to have a direct physical interpretation. In that sense, The image shows a supernova at redshift z = 0.40 (corresponding to a distance of about 6000 million light-years), observed by the 3.6-m New Technology Telescope in Chile. Observations of such distant supernovae, which appear much dimmer than expected despite their 9.8 billion years after the Big Bang. García wanted the cosmological constant is an advantageous model, distance, provided observational evidence that the expansion of our universe is accelerating – a finding that inspired the reintroduction of to consider a form of dark energy that began to play because it has a minimal number of free parameters, the cosmological constant. a role in the earlier, “radiation-dominated” epoch, all of them constrained with current observations.” from the earliest moments of “cosmic inflation”. The second thing that García admits may cause Inflation – the sudden and very rapid expansion of some caution is that the model has yet to be submitted existence in empty space, vacuum energy should be vature of space–time. This results in a space–time the early universe – is thought to have taken place to many observational probes. “We have been revis- accelerating the expansion much faster than astrono- that looks like our low-energy universe, not one with some 10−36 seconds after the Big Bang, but this rapid ing and looking for more sets of observational data to mers see in the redshifts of supernovae (figure 2). the huge vacuum energy of QFT. “We pick out par- expansion is thought to have been driven by quan- validate our models. Hence, we are creating a bridge QFT says the value of this contribution is given ticular gravity models with the behaviour that we are tum fluctuations, and not dark energy. Eventually, between theory and observational cosmology.” by the mass of the particles, which are well known, searching for,” he continues. “Vacuum energy is pre- the attractive force of gravity slowed this expansion, meaning there isn’t a problem with this aspect of QFT. sent in our approach, but it does not affect the cur- until about 9.8 billion years into the universe’s his- The “well-tempered” cosmological constant As an example of this radical difference between the vature of space–time. It does gravitate, but its effect tory, when dark energy began accelerating its expan- Forcing the cosmological constant to take a value of contribution to dark energy and the cosmological is purely felt by the new gravitational field that we sion once again (figure 1). García and colleagues, zero may lead the curious cosmologist to consider constant that QFT says particles should make, and have introduced. In this approach, the cosmological however, describe this dark energy as an entity that what happens if we do the opposite. In other words, the value that we actually observe, Appleby cites the constant problem becomes moot because it can take could have been present in both the radiation-domi- what would happen if we allow it to take an arbitrarily electron and Higgs boson. Based on their masses, any value, but its effect is not felt directly.” nated and matter-dominated epochs as a “non-inter- large value, similar to the value purported by QFT. the contributions made solely by these particles to The strength of the model – which the duo label as acting perfect fluid” that evolved with the universe’s Stephen Appleby, a cosmologist at the Asia Pacific the vacuum energy of the universe should be roughly “the well-tempered cosmological constant” – is that other components. Center for Theoretical Physics in Pohang, Republic 40–60 orders of magnitude greater than our astro- no energy scales have to be fine-tuned within it. As “The model’s strengths are the following: first, it of Korea, takes this approach to tackle the problem. nomical measurements suggest. the vacuum energy in their models doesn’t impact provides a compelling description of the universe’s He starts by assuming that the prediction given by Assuming that the value provided by QFT is cor- the curvature of space–time, the individual contri- accelerated expansion during its current epoch, QFT is correct, allowing Λ to take on the immensely rect, Appleby and his collaborator Eric Linder from butions of particles would not influence the redshift beginning around four billion years ago,” García large value it predicts (Journal of Cosmology and the University of California, Berkeley, have to explain explains. “Second, our formulation allows for evolu- Astroparticle Physics 2018 034). “Using modern cos- why the observed value is so diminutive. They do this tion with redshift instead of the cosmological con- mological observations from type Ia supernovae and by refining the idea of gravity itself. “We asked the We have been revising and looking stant, in which energy density does not change over the CMB, we can measure the total energy density of question: can we construct a theory of gravity that time.” This could explain why the theoretical value the universe, including the vacuum energy,” Appleby possesses low energy vacuum states, via lower par- for more sets of observational data suggested by QFT is larger than the value given by explains. “The value obtained from these measure- ticle contributions, despite the large cosmological the redshifts of distant supernovae. The value has ments is tiny compared to particle-physics scales.” constant?” explains Appleby. “Our analysis shows to validate our models. Hence, we evolved over time. This is because, according to QFT, every particle that such a theory can be constructed, but only by García identifies a further strength of her EDE in the universe should contribute to vacuum energy, introducing additional gravitational fields to models are creating a bridge between theory model, which is that it offers several predictions thus exerting a negative pressure that is driving the of the universe.” that match up well with practical measurements and expansion of the universe. The problem is that given Appleby and Linder have constructed a general high-resolution data concerning various stages of the estimated number of particles in the universe, as class of gravitational models, which suggests that and observational cosmology the universe’s evolution. The result is a theoretical well as the virtual particle pairs that pop in and out of vacuum energy is present, but doesn’t affect the cur-

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Lombriser has begun to explore the idea that while modifications to GR or scalar energy fields may not be responsible for directly causing the late- time acceleration, they could instead “tune” the cos- NASA/JPL-Caltech mological constant to do so. “I was surprised that I did not even have to modify Einstein’s equations to solve the problem,” says Lombriser. “I simply had to perform an additional variation with respect to a quantity that already appears in the equations – the Planck mass, which represents the strength of the gravitational coupling.” The variation results in an additional equation, one which constrains Λ to the volume of space–time in the observable universe (Phys. Lett. B 797 134804). It also explains why vacuum energy can’t freely grav- itate. Lombriser adds that by evaluating this con- straint equation with some minimal assumptions about our place in the cosmic history, he and his col- leagues can estimate the value that Λ occupies in our current cosmic energy budget. They have found this to be 70% in agreement with the dark energy contri- butions suggested by observations. “The model solves both the old and new aspects Give and take of supernovae, thereby doing away with the obser- of the cosmological constant problem,” Lombriser The opposing forces vational disparity. Therefore, the vacuum energy in explains. “The old problem of the gravitating vacuum of gravity (green) their model can be whatever value that QFT and energy and the new problem of the cosmic accelera- and dark energy particle physics predicts, without conflicting with tion with a small cosmological constant, results in (purple) combine to observed values from astronomy. This energy can this strange coincidence of us happening to live at a define the expansion even change due to a phase transition. time where the energy density is comparable to that of the universe. Despite this utility, Appleby, like García, accepts of the cosmological constant. A clear strength of the that the model he and Linder proposed isn’t perfect model is its simplicity.” and needs to be refined. “The main issue with our Lombriser also accepts there are elements to the work is that we have to introduce new gravitational solution that he puts forward that are flawed or need fields, which have not yet been observed, and the refinement. In particular, he points to the fact that, kinetic energy and potential of these additional fields due to its similarity to standard theory, the model must take a very particular form,” he says. “It is an he suggests may be impossible to falsify. “I think the open question whether such a field can be embedded way forward here is to see whether this new approach in some more fundamental quantum gravity model.” can be extended to naturally explain other poorly Appleby also points out that his model requires a understood phenomena, such as producing a natu- revision of GR, which is a hugely successful theory of ral inflationary phase in the early universe,” he says. gravity. Indeed, GR is supported by a wealth of exper- “Or we can investigate how the self-tuning mecha- imental evidence both here on Earth and beyond the nism appears from fundamental theory interactions. limits of the Milky Way. “When you modify gravity These could give rise to yet unknown phenomena in some way, you have to show that this new theory that may be testable in the laboratory.” can also pass the same stringent observational tests that GR has,” Appleby concedes. “This is a difficult The “vanilla” appeal of the cosmological constant hurdle for any gravity model to overcome, and we Of course, the three ideas discussed here could must perform these checks in the future.” prove to all be theoretical dead-ends – a leap too far for researchers who have become accustomed to the Tuning in to the cosmological constant problem mystery of the cosmological constant. Seeking to adjust theories of gravity to account Indeed, Λ could remain a problem for descrip- for the cosmological constant problem is also an tions of the universe and its expansion for decades to approach that has been considered by Lombriser come. “This cosmological constant is like vanilla ice over in Geneva. “My research in this area started out cream, it is very good, but kind of boring,” Garnavich with investigating modifications to Einstein’s theory concludes. “Removing it will make the house fall of GR as an alternative driver of the late-time accel- down unless there is a better theory to replace it.” erated expansion of our cosmos to the cosmological This will likely result in more exciting “flavours” constant,” explains Lombriser. “In 2015 I realized of ideas, theories and models until a satisfactory that for modifications of the theory of gravity to be explanation for the cosmological constant problem is the direct cause of cosmic acceleration, and not vio- found. When it comes to cosmology and science in late cosmological observations, the speed of gravita- general, there is definitely a benefit to the approach tional waves would have to differ from the speed of of “nothing ventured, nothing gained”. As Einstein light. That did not sound right, and I started to focus himself perfectly captured this ethos: “A person who on different explanations.” never made a mistake never tried anything new.” n

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 Feature: Soft matter physicsworld.com physicsworld.com Feature: Soft matter Make or break: building soft materials with DNA DNA molecules are not fixed objects – they are constantly getting broken up and glued back together to adopt new shapes. Davide Michieletto explains how this process can be harnessed to create a new generation of “topologically active” materials

Davide Michieletto Call me naive, but until a few years ago I had never up to 2 m of DNA crammed into an object just 10 μm is a Royal Society realized you can actually buy DNA. As a physicist, in size. Scaled up, it’s like storing 20 km of hair-thin university research I’d been familiar with DNA as the “molecule of life” wire in a box no bigger than your mobile phone. fellow in the School – something that carries genetic information and But if DNA molecules stayed horribly entangled, of Physics and allows complex organisms, such as you and me, to then nature would have a big problem. In particu- Dr Victor Padilla-Sanchez, PhD / Washington Metropolitan University / Science Photo Library Astronomy, be created. But I was surprised to find that biotech lar, it would be impossible for chromosomes – long University of firms purify DNA from viruses and will ship concen- pieces of DNA containing millions of base pairs – Edinburgh, UK, e-mail davide. trated solutions in the post. In fact, you can just go to be constantly read and copied. And if that didn’t [email protected]. online and order DNA, which is exactly what I did. happen, then cells would be unable to make proteins uk Only there was another surprise in store. and multiply. Thanks to the wonders of evolution, When the DNA solution arrived at my lab in nature has got round this problem by “engineering” Edinburgh, it came in a tube with about half a mil- special proteins that can change DNA’s shape, or ligram of DNA per centimetre cube of water. Keen “topology”, to get rid of the entanglements. to experiment on it, I tried to pipette some of the Left to its own devices, a typical human chro- solution out, but it didn’t run freely into my plastic mosome would take about 500 years to undo or tube. Instead, it was all gloopy and resisted the suc- “relax” its entanglements. But these clever proteins tion of my pipette. I rushed over to a colleague in can speed up the process by, for example, allowing my lab, eagerly announcing my amazing “discovery”. a DNA mole cule to temporarily split up and then They just looked at me like I was an idiot. Of course, reform. These proteins are vital to the operation of solutions of DNA are gloopy. biological cells – that’s why the DNA I bought online I should have known better. It’s easy to idealize was so gloopy: it had was a pure form that had no DNA as some kind of magic material, but it’s essen- proteins to undo the entanglements. tially just a long-chain double-helical polymer con- Unfortunately, there can be an over-abundance of sisting of four different types of monomers – the these proteins in certain cancer cells, which there- nucleotides A, T, C and G, which stack together into fore multiply incredibly fast as the proteins remove base pairs. And like all polymers at high concentra- the entanglements so efficiently. Indeed, some of the tions, the DNA chains can get entangled. In fact, first and most effective anti-cancer drugs were those they get so tied up that a single human cell can have that could stop so-called “type 2 topoisomerase” pro- teins from getting rid of entanglements. These drugs have some nasty side effects as topoisomerase pro- By combining our knowledge of teins also play a vital role in ordinary, healthy cells. But would you believe me if I said that DNA’s abil- polymer physics and molecular ity to morph its architecture means that it behaves a bit like soap? The link between DNA and soap is cer- biology, we can exploit DNA’s tainly surprising. But by combining our knowledge of polymer physics and molecular biology, we can soap-like behaviour to craft exploit this soapy feature to craft DNA-based soft materials that change topology over time. And by tweaking their topology, we can control their physi- DNA-based soft materials that cal properties in unusual ways.

change shape over time A wormy tale To understand the link between DNA and soap, I should point out that soaps and shampoos consist of “amphiphilic” molecules, one part of which loves water and another part that hates it. These molecules don’t exist in isolation but group together to form

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1 Soap, shampoo and worm-like micelles sual flow properties, such as the viscosity of soaps 2 Topological operations in DNA dropping drastically when sheared. Indeed, this a b sudden loss of stickiness explains why hand lotions, shampoo and creams, which are viscous when left alone, can be easily squeezed out of tube with a nar- row nozzle. Davide Michieletto Davide Davide Michieletto Davide Breaking and reconnecting So just like worm-like micelles in soaps, DNA mol- ecules are constantly getting broken up and glued back together again with a new topology (figure 2). But there’s one big difference: the DNA needs to c preserve its genetic sequence otherwise cells might die or diseases could be triggered. In soap, there’s no precise sequence of monomers in micelles so they can be put back together in any order. Nature, however, requires proteins to perform topological operations on DNA while maintaining the original information (the DNA sequence) intact. This has a fundamental impact on how topological operations are performed on DNA. Unlike worm- like micelles – where the operations can occur at random anywhere along the micelle and at any time – the topological changes on DNA have to happen at the right place and the right time (they have to a Soaps and shampoos are made from amphiphilic molecules with water-loving (red) and be “regulated” as biologists love to say). It’s a mind- Like worm-like micelles in soaps, DNA chains can also undergo various topological operations, although they require proteins to occur. water-hating (blue) parts that arrange themselves to form long tubes known as “worm-like Shown here are chains splitting and re-connecting (using recombinase protein, green); splitting and re-crossing (using topoisomerase blowing concept – and one that I’ll be spending the protein, yellow); fusing (using ligase proteins, cyan); and breaking (using restriction enzymes, purple). The first two processes are reversible micelles”. Entanglements between the tubes give these materials their pleasant, sticky feel. next five years trying to artificially reproduce, to cre- b The micelles can, however, disentangle themselves, just as entangled long-chain polymer with the same protein, whereas the others are not. ate a new generation of materials. molecules can slide apart too. In polymers, this process can be modelled by imagining the molecule sliding, like a snake, out of an imaginary tube formed by the surrounding spatial To break DNA, for example, you need “restriction constraints. c Worm-like micelles can also morph their architecture by performing enzymes”, which cut the chain only where a certain information. Recently, there’s also been lots of work others nearby to form an architecture that looks a reconnections (left), breakages (down) and fusions (right). These operations occur randomly DNA sequence is recognized. Topoisomerase pro- on “DNA origami”, in which the information along bit like medieval chain mail. What’s even more fas- along the backbone, are in thermal equilibrium and reversible. teins, meanwhile, have to be precisely positioned the DNA chain is now stored in 3D shapes (fig- cinating is that this topological structure is continu- at certain locations on chromosomes where entan- ure 3a). Indeed, we could even see nano-robots or ally splitting up and reassembling correctly at each glements and mechanical stress often accumulate. nano-machines made from DNA. cell division. larger structures, known as “micelles”. At low con- Similarly, when two pieces of DNA reconnect and What excites me about this line of research is that centrations, they’re usually spherical, but at higher recombine – for example when parental genetic solutions of DNA, functionalized by the presence of Interdisciplinary research from the bottom up concentrations, the molecules can gang together to material is shuffled in gametes (the precursor of egg proteins that can change DNA’s topology in time, Apart from their intrinsic scientific interest, studying form long, worm-like micelles, with the water-hating and sperm cells) – the process is tightly regulated may yield novel “topologically active” complex flu- such biological structures will also help us design a parts of the molecules facing inside (figure 1a). in space and time to avoid aberrant chromosomes ids that respond to external stimuli. These fluids and new generation of self-assembled topological mate- Ranging in size from nanometres to microns, these in cells. It’s almost as if DNA (thanks to proteins) is nanomaterials would exploit the information-stor- rials. These complex, DNA-based materials hold elongated, multi-molecule objects do strange things a smart worm-like micelle. ing abilities of DNA to form complex 3D shapes or great technological promise, but to make progress at high concentrations. In particular, just like DNA, While all this may sound rather esoteric, it turns hybrid scaffolding with the responsiveness, plasticity we need multidisciplinary teams of physicists, chem- they get entangled, increasing the fluid’s friction and out that when the US microbiologist Hamilton Smith and precision endowed by specialized proteins (fig- ists and biologists working together. What’s more, making it harder to deform. In fact, the entangle- discovered the first restriction enzyme in the 1970s, ure 3b). For example, adding restriction enzymes that they will have to work from the bottom up, explor- ments between worm-like micelles are what give your he didn’t use any fancy biological techniques – but can cut the DNA at specific sequences could allow ing basic principles for curiosity’s sake, and not only soap, shampoo, face cream or hair gel that pleasant, simply carried out accurate viscosity measurements. stiff and robust DNA-based scaffolds to be degraded trying to solve specific technological problems that smooth hand-feel, which is something to think about Having extracted DNA from a virus and mixed it as soon as they are no longer needed. That could be industry faces. next time you’re taking a bath or shower. with the insides of a bacterium, he saw that the vis- useful if you’re using a scaffold to, say, regenerate One notable success story in this regard, at least Just like polymers, it turns out that worm-like cosity of the DNA solution fell with time; the runnier a bone in a patient’s body: once the scaffold is not micelles can also disentangle themselves by sliding liquid meant that the DNA must have been cut by an needed any more, you can get rid of it. apart (figure 1b). But they have other options too. enzyme in the bacterium. Smith won the 1978 Nobel At the same time, adding topoisomerase to an Solutions of DNA, functionalized by That’s because worm-like micelles are continuously Prize for Physiology or Medicine for his efforts and ensemble of DNA plasmids (circular DNA) can morphing: they break up, fuse or reconnect with it’s humbling to think it was all done with a simple create a gel, in which the rings of DNA are joined the presence of proteins, may yield their neighbours – no micelle is the same at any two viscosity experiment that has its roots in physics. together like the rings on the logo of the modern- points in time (figure 1c). This ever-changing feature day Olympic Games (figure 3c). These “Olympic novel “topologically active” complex wonderfully embodies the Greek philosopher Hera- DNA and nanotechnology gels” have proved impossible to synthesize in the lab clitus’s concept of “panta rhei”, or “everything flows” I’m definitely not the only person to see the poten- despite decades of trying, yet nature has been doing fluids that respond to external stimuli (from which the term “rheology” for the study of flow tial of DNA as an advanced polymer, rather than so for millions of years. is derived). Indeed, micelles almost seem like quasi- just as genetic material. Over the last two decades, In fact, I find it amazing that a type of unicellular living objects, thanks to their ability to morph their researchers have developed lots of new, DNA-based organism called trypanosomes base their very exist- architecture and, sometimes, even their topology. materials, such as hydrogels and nano-scaffolds, that ence on this Olympic gel. In particular, part of their This interplay between dynamic architecture and could, for example, grow bones, tissues, skin and genome takes the form of a giant network in which conventional relaxation can lead to some highly unu- cells, using the unique properties of DNA to encode each DNA minicircle is linked to about other three

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a

Davide Michieletto Davide Looking for cosmology books? Look no further than the AAS–IOP Astronomy collection.

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Expand your reach and engagement The benefits of choosing a digital-first publisher Publish your research and reference text, course text, or broad interest title in the AAS–IOP Astronomy collection and benefit from circulation to peers at targeted institutions and conferences, as well as timely marketing campaigns, member newsletters, Rapid Multimedia Full-color print a DNA origami is the art of folding a single-stranded DNA “scaffold” (left) into complex 2D and 3D shapes (smiley face, right) using hundreds of “staples” – short and much more. publication content copies single-stranded DNA fragments that uniquely match part of the scaffold DNA (middle). b Smart, responsive gels can be made using DNA and restriction enzymes. times c So-called “Olympic gels”, with linked rings of circular DNA, can be self-assembled by combining DNA plasmids (circular DNA) with topoisomerase protein. We welcome proposals in all areas of astronomy, astrophysics, and planetary science. here in the UK, has been the creation of the Physics of this kind, while research centres that cut across Choose the right publisher for you of Life network, led by the physicist Tom McLeish, traditional academic disciplines will be vital too. It which has seen the country’s research councils invest is an exhilarating field to be in, where everyone – no If you are interested in being part of this rapidly in this area. Now bearing fruit, I hope it’s the start matter where they are in their career – learns some- expanding book series, we’d like to hear from you. of a stable, long-term, interdisciplinary programme thing new every day. My hope is that in 10 or 20 years’ Submit a summary of your proposal, including a No Digital e-reader A dedicated, of support. The Biological Physics Group of the time, scientists who are starting out in their careers current biography and contact details, to Rights compatibility hands-on editor Institute of Physics, which publishes Physics World, will no longer feel obliged to explore only one spe- Management is also playing a key role in encouraging more groups cific discipline or to choose between theoretical and [email protected]. to embrace this multidisciplinary approach at the experimental work. Instead, it would be great if they interface between soft matter and biological physics. could simply satisfy their scientific curiosity no mat- However, we still need more top-quality journals ter what background they are from. For if they do that recognize high-value interdisciplinary research that, who knows what we might find next? n

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Hamish Johnston reviews Superheavy: Making and Breaking the Periodic Table by Kit Chapman

Like many physicists, the last time that I had a serious look at a periodic table was when I took my last chem- istry course – which was 35 years ago – and I rather sheepishly admit that studying the table once more was a revelation. Indeed, I wondered aloud “Where did all those new superheavy elements come from?” Even though as a physics journalist I have covered the twists and turns in the discovery and naming of new elements over the past two decades, I had always looked at each element in isolation and did not fully appreciate how the periodic table – full of holes when J Hosan/GSI HelmholtzzentrumSchwerionenforschungGmbH Hosan/GSI für J I was young – appears much more complete, at least for now. What I mean by complete is that in the current incarnation of the familiar version of the table, the sev- enth and final row is full of elements named after people and places – there are no gaps and no system- atic names such as unnilseptium that were placeholders as scientists argued over element names. The seventh row begins on the left with francium and radium; is punctuated by the 14 actinoids (from actinium to lawrencium); and then makes the Heavy findings Atomic nuclei have been intensely before decaying. It is the heaviest of sprint across the transition metals The Separator for researched for more than a cen- these rare nuclei, and the people who and on towards the noble gases. Heavy Ion reaction tury, but they remain things of mys- devoted their careers to discovering The superheavy elements are the careers Products (SHIP) at tery and wonder – especially to the and characterizing them before they final 15 in this row, from rutherfor- the GSI lab in nuclear physicists who study them. decay, that are the subject of Super- dium with 104 protons to oganesson Career opportunities for those with a background Darmstadt, We know that nuclei are made of pro- heavy: Making and Breaking the Peri- with 118. Those last two names, by Germany, is just one tons and neutrons bound together odic Table by the pharmacist turned the way, reflect the importance of in physics and related subjects nuclear-physics by the residual strong force. But the science writer Kit Chapman. the Soviet/Russian Joint Institute set-up looking for extreme difficulty of calculating The book takes the reader on a for Nuclear Research (JINR) in superheavy nuclear properties using the Stand- romp that begins in 1930s Paris, when the search for superheavy elements. A bumper-sized book with helpful careers advice, real-life case studies, elements. ard Model of particle physics leaves Irène and Frédéric Joliot-Curie dis- The lab is in Dubna, near Moscow much to be learned about their inter- covered that heavier elements could and since 1989 it has been run by as well as an extensive employer directory. Superheavy: nal workings. In a sense, nuclei are be made by bombarding lighter ele- Yuri Oganessian. Strictly speaking, Making and like the world’s oceans: despite their ments with alpha particles (helium new elements should not be named Breaking the ubiquity, we are still on the shoreline nuclei). This was followed shortly after living people, but two excep- Download the free Physics World app today! Periodic Table trying to understand what lies in thereafter in Rome by Enrico Fermi tions have been made – oganesson Kit Chapman their depths. and the “Via Panisperna Boys” who (118) and seaborgium (106), the lat- 2021 Bloomsbury Nuclei are made of just two com- found that bombardment with neu- ter honouring the nuclear chemist Sigma £10.99pb ponents, but their properties can be trons had a similar effect. Glenn Seaborg, who created and ran 304pp very different indeed. Most of the The race was on to find new heavy the rare elements programme at the nuclei in your body, for example, have elements and the result was a trans- University of California, Berkeley. been around for billions of years, yet formation of the periodic table – GSI in Darmstadt, Germany, and some rare nuclei made in the lab can which is conveniently included in RIKEN’s Radioactive Isotope Phys- Read online at physicsworld.com/careers last just tiny fractions of a second the frontmatter of Chapman’s book. ics Laboratory in Japan were also Physics World March 2021 55

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V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishing Ltd 2021 Reviews physicsworld.com WE ENABLE UNMATCHED DATA ACQUISITION PERFORMANCE. BUY WITH CONFIDENCE FROM A TRUSTED BIG PHYSICS SUPPLIER. major contributors to the discovery transfermium referring to elements of the superheavy elements. They Atoms formed by beyond fermium (100). The wars ran have been honoured with the names for about 30 years, starting in the darmstadtium (110), hassium (108) superheavy 1960s, and during this period three and nihonium (113) – the last two different elements had been named inspired by the Latin name for the rutherfordium by different research German state of Hesse and an alter- elements have groups and three different names native name for Japan. had been proposed for element Like many things in modern phys- properties that 102. What is more, two different ics, the drive to create superheavy names had been proposed to hon- elements began in earnest during are not predicted our the Danish physicist Niels Bohr the Second World War with the race – bohrium and nielsbohrium – the to build the atomic bomb – and spe- latter favoured by the Germans who cifically the development of a way by their position were concerned that bohrium could to produce significant amounts of be confused with boron. plutonium. That element was dis- in the periodic In 1986 the Transfermium Work- covered in 1941 at the University of ing Group was set up by the govern- California Berkeley by a team that table ing bodies of chemistry and physics included three future Nobel laure- (IUPAC and IUPAP respectively) ates: Seaborg, Emilio Segrè and to sort out the mess and after a dec- Edwin McMillan. ade-long slog it finally came up with Chapman reveals that Seaborg a definitive list of names in 1997 – chose the symbol Pu for plutonium and bohrium (107) won out over because of the stench of his Berke- nielsbohrium. ley chemistry lab. Although physi- As for the future of the superheavy When Compromise is Not an Option. cists had played an important role element hunters, Chapman writes in the early discovery of new ele- that the best guess of physicists is ments – the work of Seaborg and that there could be as many as 172 colleagues was made possible by elements – which means more than High-Performance Digitizers for the cyclotron, which was invented at 50 could still be up for discovery. But Berkeley by the physicist and Nobel Chapman also points out that discov- laureate Ernest Lawrence – it was ering more and more heavy elements Big Physics Applications chemists who isolated the new ele- could be the undoing of the periodic ments from bombarded targets. This table, bringing about the “end of Digitizers from Teledyne SP Devices utilize patented was no mean feat; not only did they chemistry”. While that might sound have to predict the chemistry of an ominous, I’m afraid it doesn’t mean calibration technology, the latest data converters, and element that had never been seen that chemistry students of the future state-of-the-art FPGAs in order to achieve an unrivaled before, they also had to work very can avoid learning how to balance quickly because the elements have redox reactions. What Chapman combination of high resolution and sampling rate. Their short half-lives. Indeed, Chapman in the most discoveries. In 1993 he means is that the atoms formed by versatility makes them ideal for applications such as tells us that Berkeley nuclear scien- helped discover element 106, put- superheavy elements have properties tist Albert Ghiorso famously used ting his tally at 11 and beating the that are not predicted by their posi- beam position monitoring, Thomson scattering plasma a souped-up Volkswagen Beetle to 185-year record held by Humphrey tion in the periodic table – a corner- diagnostics, and more. transport samples in the shortest Davy. Because the discovery was stone of chemistry. time possible across the campus, made at Berkeley, the lab gained the An early hint of this is that research from where they were made to where right to name the element. This was using tiny numbers of copernicium Supported features include: they were analysed. at a time when Berkeley, JINR and (112) and flerovium (114) atoms at Because much of the early effort to Darmstadt were in competition to Dubna suggests that the element’s • Up to 10 GSPS sampling rate with 14 bits resolution create new elements occurred during find and name new elements. chemical properties are not as the Second World War and the Cold The days of isolating new elements expected given its place in the peri- • Open FPGA for custom real-time signal processing War, there was a certain amount of and studying their chemistry was odic table. Flerovium, for example, censorship involved in publication waning. By the 1990s researchers should behave like lead, which is the • Multiple form factors including MTCA.4, PXIe, and PCIe of the work. Before the US entered often only caught fleeting glances of element above it in the periodic table • Multi-channel synchronization capabilities the war in 1941, Chapman points out new elements and had to try to deter- and copernicium should behave like that the British were concerned that mine their decay chains – often only mercury – but that is not what the • White Rabbit synchronization (MTCA.4 only) American scientists were provid- seeing part of the picture. Science study found. The likely reason is that ing the Germans with information is usually done incrementally with these elements have huge charges on • Peer-to-peer streaming to GPU (PCIe only) that could be used to create nuclear different labs contributing evidence their nuclei and large numbers of weapons. In 1945 US officials pre- that eventually adds up to a discov- electrons, so that conventional way • Application-specific firmware shortens design time vented the publication of a Superman ery – giving priority as to who made of understanding how these ele- comic strip because the superhero a discovery and who therefore had ments react breaks down. was irradiated in a cyclotron – which naming rights was a tricky business. So rather than heralding the end was described with too much accu- While this competition between of chemistry, the superheavy ele- rate detail for wartime censors. labs resulted in a flurry of new ele- ments look set to open an exciting While Seaborg is the scientist ments, the labs were at loggerheads new chapter. most associated with the discovery when it came to naming the new of new elements, it is Ghiorso who elements. This ruckus was dubbed Hamish Johnston is an online editor of holds the record for being involved the “Transfermium Wars”, with Physics World Learn more on our website www.spdevices.com 56 Physics World March 2021

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A deeply human story of Fred Reines who won the Nobel Prize Strolling in the deep for his discovery of the neutrinos “… compelling personal and scientific Ian Randall reviews The Brilliant Abyss: True Tales of Exploring the Deep Sea, Discovering Hidden Life account of a remarkable pioneer” and Selling the Seabed by Helen Scales Arthur B McDonald Nobel Laureate in Physics wake – not to mention kicking up a in the North Sea in 2015; as well as “captures the excitement of lingering muddy cloud that chokes explaining why some fish have scales experimental neutrino physics.” and smothers those survivors such as that are blacker than the darkest Jonas Schultz, Particle Physicist corals and sponges that are unable to material man has ever engineered A creative combination of Amazon Bestseller 4.7 / 5 flee and escape it. – the multiwalled carbon nanotube, Choice Outstanding Academic science writing and fiction, Over 40,000 copies sold worldwide Raising the alarm about this eco- Vantablack, which is up to 99.965% Title 2020 from the New Yorker writer logical vandalism against a realm absorbent. One thing that struck me Jeremy Bernstein Davidshale/naturepl.comL© about which we know precious little while reading The Brilliant Abyss is What our customers say: Explains loop quantum gravity is the raison d’être of marine biologist that despite being an erstwhile stu- "It really feels like sitting as to beginners without using “Structures of academic papers are very Helen Scales’ beguiling new book The dent of geology and having learnt the an observer on a sparkling mathematics well explained with many examples.” Brilliant Abyss: True Tales of Exploring names given to Earth’s past super- conversation that bounces from O. Ertugrul the Deep Sea, Discovering Hidden Life continents, I don’t recall ever having "This book offers a fascinating topic to topic." and Selling the Seabed. With her light given thought to the correspond- “Writing a paper used to be a nightmare introduction to an esoteric realm Brain Clegg, Science author and engaging prose, Scales takes the ing “superoceans” that surrounded otherwise accessible to only a for me. This book has certainly helped me reader on an introductory dive into them, such as Mirovia and Pantha- fortunate few.” alleviate the fear.” the mysterious depths to reveal the lassa. A shift of perspective is always mosquitoboat CHOICE myriad of life hidden within, from fascinating. red and green bone-devouring It is perhaps in the final third of worms that flourish whenever whales the book that Scales’ argument for View these books & more at www.tinyurl.com/wspopphys fall down to the abyss, to the world’s the preservation of the deep from fishiest-smelling fish. There’s even a exploitation becomes most clear. hunt for yetis – not of the elusive kind, She explores the medical potential but tiny, blind, pale crabs that survive of deep-sea organisms – such as living around deep-sea hydrothermal sponges that harbour anti-cancer vents and cold seeps by farming bac- compounds – and weighs up the teria to feast on. Like their abomi- benefits and risks of farming the ENVIRONMENTAL RESEARCH OPEN nable namesakes, however, they are deep for food and mining it for its INFRASTRUCTURE ACCESS very hairy. mineral resources, before calling for Strange and At the bottom of the North Central As The Brilliant Abyss’ subtitle the reader to join her in campaign- AND SUSTAINABILITY Medical physics beautiful Pacific Ocean, some 5000 m beneath suggests, the work periodically seg- ing for humanity to leave the deep The yeti crab is just the waves, lies a small, fist-sized ues into arresting tales from Scales’ free from excessive interference. It’s Par t of the Environmental Research series one of the weird black rock, with a knobbly surface career, from recovering experiments a compelling argument – although from IOP Publishing and biophysics deep-sea creatures texture, like a head of broccoli. It to determine what species of clams, one that might perhaps have been in Helen Scales’ new holds a secret at its heart – a sin- worms and sea cucumbers colonize more strongly seeded in the opening Bringing together all communities addressing important Find the information you need from IOP Publishing’s book. gle tooth, long ago shed by a shark logs swept out to sea by floods and chapters of the work. swimming in the waters above. In the hurricanes, to weathering out high One mild disappointment of the challenges relevant to every aspect of infrastructure world-leading journals and award-winning books programme, along with conference proceedings and The Brilliant Abyss: manner of a pearl forming around a winds that suspended scientific book for me is that there are not and sustainability. True Tales of piece of grit in an oyster, the tooth activity during a research expedition more illustrations or pictures of the science news from Physics World. Exploring the Deep has become encapsulated by layers in the Gulf of Mexico. weird and wonderful creatures intro- Why should you publish with ENVIRONMENTAL RESEARCH Sea, Discovering of waterborne minerals that settled Fascinating titbits abound in duced in the text (at least in my pre- INFRASTRUCTURE Environmental Research: iopscience.org/medical-physics-and-biophysics AND SUSTAINABILITY TM Hidden Life and Infrastructure and Sustainability ? out of the water around it. It took Scales’ writing – including the rev- view copy). Scales’ descriptions may iopscience.org/eris Selling the Seabed elation (to me, at least) that diving Multidisciplinary scope millions of years to reach its current be beautifully written and highly • Helen Scales size – but it shall grow no bigger. mammals such as whales and dol- evocative, yet a picture is, as the cli- Flexibility for your research • 2021 Bloomsbury A vast unmanned, electric sub- phins have evolved a special, “non- ché goes, worth a thousand words. High quality • Sigma £316.99hb mersible ploughs across the seabed stick” form of the oxygen-carrying, The exception is the gorgeous cover Open access • 352pp like a bulldozer, heaving up our rock haemoglobin-related protein myo- art of various deep-sea species by (among others) with its teeth, before globin in their muscles. These each the artist Aaron Gregory, in a style Editor-in-Chief sucking it up a hose to a ship wait- have a slightly negative electric that seems to evoke the illustrations Arpad Horvath, charge that repels other myoglobin of the German zoologist and artist University of California, Berkeley, USA ing on the surface. These nodules are rich in metals like nickel, copper molecules, allowing the mammals Ernst Haeckel, whose work is dis- and cobalt – and industry has come to carry 10 times the protein that we cussed in the book. to mine them. But the abyss is not do without the molecules clumping This quibble aside, The Brilliant To find out more about submitting, please visit empty, making this activity not with- together and causing their bodies to Abyss is a wonderfully written read iopscience.org/eris or e-mail [email protected] out its victims. Our rock and its peers go completely stiff. that I would highly recommend – it’s supported an abundance of life, from Scales’ book also explores such the ideal plunge into the depths of worms and starfish to crustaceans fascinating cases as whether coronal Earth’s last great wilderness. and ghost-like octopuses. As the mass ejections from the Sun could mining machine lurches onwards, have contributed towards stranding Ian Randall is a science writer based in it leaves a trail of devastation in its numerous young male sperm whales Cambridge, UK

Physics World March 2021 59

PWMar21_p.inddENVIRONMENTAL 1 RESEARCH 19/02/2021 11:33 PWMar21reies.indd 9 19/02/2021 10:1 OPEN www. INFRASTRUCTURE AND SUSTAINABILITY ACCESS Medical physics Part of the Environmental Research series from IOP Publishing V o l u m e 3 4 N u m b e r 3 M a r c h 2 0 2 1 © IOP Publishingand Ltd 2021biophysics ENVIRONMENTAL RESEARCH A new open access multidisciplinary journal that brings INFRASTRUCTURE together all communities addressing important challenges AND SUSTAINABILITY Find the information you need from relevant to every aspect of infrastructure and sustainability. iopscience.org/eris IOP Publishing’s world-leading journals Why should you publish with Environmental Research: and award-winning books programme, Infrastructure and Sustainability TM ? along with conference proceedings and • Multidisciplinary scope • High quality science news from Physics World. • Flexibility for your research • Open access Editor-in-Chief Publish with us Arpad Horvath, University of California, Berkeley, USA We offer a range of publishing options to suit your needs, ensuring that your work gets the attention that To find out more about submitting, please it deserves. visit iopscience.org/eris or e-mail [email protected] iopscience.org/medical-physics-and-biophysics physicsworld.com Careers Rethinking nuclear for a greener planet Troels Schönfeldt, co-founder and chief executive of Danish start-up Seaborg Technologies,

talks to Julianna Photopoulos Technologies Seaborg about his career in nuclear and particle physics – and how he unintentionally became an “impact entrepreneur”

Troels Schönfeldt is a physicist who has had an innate curiosity about how and why things work since childhood. However, his career path into physics “took quite a big detour” thanks to his decision to leave school at the age of 16 and travel around Europe. “I was not the typical career guy,” he says. “I started off as a dropout but then I got back on track.” Today, he is the chief execu- tive of Copenhagen, Denmark-based start- up company Seaborg Technologies, which is working towards manufacturing and com- Supplying reliable mercializing a safer, cheaper and cleaner DUNIWAY vacuum equipment nuclear reactor – a Compact Molten Salt since 1976 STOCKROOM CORP. Reactor (CMSR) – that cannot be weapon- ized, or result in a nuclear disaster. Schönfeldt’s interest in physics was piqued after he returned to school and found it gave him the deep understanding and knowledge he longed for. He had spent Mechanical five years working as a laboratory assistant Ion Pumps Turbo Pumps Pumps at Danish company Coloplast, which manu- factures medical devices, before returning to his studies. “I still wanted to know how and why,” he recalls. His initial goal was to earn a chemistry degree but he soon real- ized that for him physics was “the king of science”. He graduated from the Niels Bohr Institute of the University of Copenhagen Impact entrepreneur Co-founder and chief executive of Seaborg Technologies Troels Schönfeldt. in 2011, with a Master’s degree in particle Gauge Vacuum Controls Sensors physics, in collaboration with CERN in Talking nuclear D Geneva, Switzerland. During his PhD, Schönfeldt occasionally I was not the typical Schönfeldt continued his studies at the met up with two fellow physicists he had environment Technical University of Denmark (TUD) known through his Master’s to brew beer career guy. I started and the European Spallation Source (ESS) and discuss nuclear power. “We called it in Lund, Sweden, and earned his PhD in the Beer Nuclear Power Club,” he recalls. and energy neutron physics in 2015. “I worked on Each meet-up concluded with them com- off as a dropout but advanced neutron moderators, so I had to plaining about how nuclear was not being Stay up to date with the latest breakthroughs in design the ESS moderator system to slow used as a solution for the climate-change then I got back on down the fast neutrons the source produced, crisis. One night in 2014 they decided to Hardware Supplies Diffusion all areas of environmental science, bought to you Pumps and make them useful for neutron scatter- take matters into their owns hands and track from the number one science news service. ing experiments,” he explains, adding that start a company, becoming “impact entre- “The moderator now actually has a specific preneurs” – those who start companies with www.duniway.com physicsworld.com/environment-and-energy shape – the so-called butterfly moderator – the aim to generate change in society, and 800.446.8811 (Toll Free) 650.969.8811 (Local) 650.965.0764 (Fax) which I came up with as part of my PhD.” improve lives. “We didn’t even know what a company was, but nobody was reacting;

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environment and energy

Stay up to date with the latest breakthroughs in all areas of environmental science, bought to you from the number one science news service. physicsworld.com/environment-and-energy physicsworld.com Careers physicsworld.com Recruitment Advertising Tel +44 (0)117 930 1264 Physics World Fax +44 (0)117 930 1178 IOP Publishing E-mail [email protected] Recruitment Temple Circus, Temple Way Bristol BS1 6HG

reactor vent mast The place for physicists and engineers to find Jobs, Studentships, Courses, Calls for Proposals and Announcements compartments reactor Seaborg Technologies crane compartments living quarters turbine hall 180 cm Planning your next career move? 32 m 22 m CERN, the largest particle physics laboratory in the world, is seeking to hire an experimental physicist to join this important reference centre for the European physics community in a stimulating scientific atmosphere. accommodation control centre

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Change is afloat Seaborg Technologies are hoping to get their first commercial reactors running on power barges in south-east Asia in the next four years. Find out more http://cern.ch/go/w6Tt

sometimes you cannot expect other peo- mindset you have as a physicist is valuable nuclear power source up and running by ple to do it, you have to do it yourself,” in business, but you cannot do everything 2025. “To make it truly impactful we will Schönfeldt says. as a physicist.” place our reactors on power barges and Deadline 30 March 2021. At first, Seaborg Technologies – named mass produce them at Korean shipyards, after US nuclear chemist and Nobel laureate Learning business and then tow them to seaside cities in Glenn T Seaborg – started as an ambitious Schönfeldt unintentionally became chief south-east Asia.” volunteer project, where the three worked executive after his co-founders nominated on the technology in their spare time. “We him for the role. “I was 10 minutes late for Maintaining company culture were trying to pick up from where the that meeting,” he recalls, “I had no interest As Seaborg Technologies’ chief executive, Molten Salt Reactor Experiment was shut in being the CEO, I wanted to do physics.” Schönfeldt’s job involves lots of meetings, down in the 1960s. They didn’t have the Over the next few years, Schönfeldt learned navigating opinions and stakeholders, and computers to calculate the advanced calcu- the ins and outs of business, licensing pro- ensuring everyone is happy. “Culture is fun- lations they needed to handle neutronics in cesses, commercialization, management damental for any company, and building it a liquid,” says Schönfeldt. In the meantime, and human resources. “I started to love and requires a lot of nurturing and a lot of work,” Schönfeldt finished his PhD in 2015 and understand being the CEO. It turned out it he says. He often misses doing physics, but had several postdocs lined up. “My plan was a really lucky choice.” at the same time, he enjoys the varied chal- was to take one of those offers, but I was After refining the business plan, Seaborg lenges. “We have a lot of clever heads here so much in love with Seaborg Technologies Technologies found its first investors in and my main role is to ensure that they have that I actually said no and went full time 2018, and since then has received numer- the framework to solve problems – not solve with no salary.” ous funding from venture capital funds, them myself,” says Schönfeldt. The company designed its compact grants and private investors. “We started Having ended up in a career that he never molten salt reactor that same year, aiming off really small, but we have grown to about expected, Schönfeldt pauses before giving to provide electricity, clean water, heating 30 people from five continents – including advice to today’s physics graduates. “It has and cooling to around 200 000 households physicists, nuclear engineers, chemists, been a hardcore transition – founding a with renewable energy. The liquid salt is safety experts and business developers – company is the best thing you will ever do, used as a neutron moderator that acts as and we’re now in the process of hiring 50 but it’s also the worst,” he says. Even so, he a catalyst to improve the chain reaction more. We also receive a couple of handfuls encourages them to think outside the box to – similar to what Schönfeldt had previ- of interns every year,” he says. create change in the world. “Please start a ously worked on. “My PhD geared me very In 2019 Seaborg Technologies built its company. The world needs young creative well to work on nuclear reactors,” he says. own small-scale laboratory, enabling on- people and new ways of thinking. But don’t Soon after, two other physicists and a serial site experimental research. “We are well expect to know and solve everything from entrepreneur joined the team, became co- under way to license the next generation the beginning, your physics skills might not founders and helped set up the company of nuclear reactors to save the world,” be where you end up.” properly. Schönfeldt points out that having Schönfeldt says. Despite setbacks due to an entrepreneur on the team really helped coronavirus, he explains their goal still Julianna Photopoulos is a science writer based in with the business side of things. “The remains to have the first commercial Bristol, UK, e-mail [email protected]

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““So,So, areare electricityelectricity andand magnetismmagnetism thethe samesame thing?”thing?” City University of Hong Kong is a dynamic, fast-growing university that is pursuing excellence in research and professional education. As a publicly funded institution, the University is committed to Noah,Noah, aged aged 12 12 nurturing and developing students’ talents and creating applicable knowledge to support social and economic advancement. The University has nine Colleges/Schools. As part of its pursuit of excellence, the University aims to recruit outstanding scholars from all over the world in various disciplines, including business, creative media, data science, energy and environment, TheThe IOP IOP is is awarding awarding 200 200 scholarships scholarships worth worth £26,000 £26,000 -- Getting Getting involved involved with with the the scholar scholar community, community, to to interact interact engineering, humanities and social sciences, lalaw, science, veterinary medicine and life toto talented talented individuals individuals who who are are passionate passionate about about andand network network with with your your fellow fellow scholars scholars via via online online events events sciences. physicsphysics and and have have the the potential potential to to become become inspirational inspirational -- Free Free IOP IOP membership membership for for your your training training year year Applications and nominations are invited for: teachers.teachers. Scholarships Scholarships are are for for those those starting starting teacher teacher trainingtraining in in England England in in September September 2021. 2021. DiscussingDiscussing thought-provoking thought-provoking questions questions with with enquiring enquiring Chair Professor/Professor/Associate Professor/Assistant Professor mindsminds is is at at the the heart heart of of teaching teaching physics. physics. Department of Physics [Ref. A/460/09] AsAs an an IOP IOP scholar scholar you you will will benefit benefit from: from: You’llYou’ll help help your your students students to to understand understand the the world world around around The targeted research themes include: Computational Physics and Theory; Scattering and Imaging; -- Access Access to to physics physics teaching teaching workshops workshops them,them, capturing capturing their their imagination imagination and and preparing preparing them them for for Low-dimensional Materials; Soft Matter and Biophysics; Atomic, Molecular, and Optical Physics. However, exceptional candidates outside the focused areas will also be considered. thethe future. future. -- Support Support to to develop develop your your physics physics teaching teaching skills skills includingincluding online online Continuing Continuing Professional Professional Development Development For more information, please visit the departmental website, https://www.cityu.edu.hk/phy/. (CPD) workshops To apply, please submit an online application at http://www.cityu.edu.hk/hro/en/job/current/ (CPD) workshops academic.asp?ref=uac-a460, and include a curriculum vitae, along with a concise statement of re- search interests and teaching philosophy (up to 2 pages each.).

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NanoMEGAS (www.nanomegas.com) is a leading “high tech” Requirements company established in 2004 in Brussels and active in electron Experience: Engineering degree (Electrical, Electronic) microscopy/advanced electron diffraction techniques. We develop • 2 years minimum experience in lab or self-directed project. Alternatively a hardware & software solutions able to retrofit in various TEM previous experience in service work on SEM/TEM electron microscopes will be electron microscopes. Our hardware product range is compatible a plus, but not mandatory • important to have hands-on experience (assembly, fabrication/modification, with most commercial TEM electron microscopes (including Cs wiring) corrected TEMs) and latest technology CCD cameras/Direct • ability to communicate technical information effectively. Open to working in a Detection detectors. There are more than 800 scientific publications small international team and flexible environment (period 2004-2020) where Nanomegas related instrumentation has • PCB design experience will be a plus been used from more than 200 TEM laboratories worldwide. Skills • use of soldering iron and measurement devices (multimeter, oscilloscope etc.) We are looking for new talented and self-motivated service engineers to • sense of negotiation, strength of proposal in technical matters, a will to strengthen our team with a profile as listed: coordinate technical team establishing priorities • quality: organized, autonomous, involved, result-oriented, loving challenges and Description teamwork As an Electronic/Industrial Engineer you will be responsible for your sector • language: fluent & operational English is imperative, and French or Dutch would and responsible for assembling and installing our technologies/systems to be a plus clients. You will support on site or remotely to our customers and will also • computer skill: familiarity with windows 10 OS. Knowledge of programming interact with third party microscopy companies. languages would be a plus You will be primarily responsible for: What to expect • assembly and quality control of our hardware/software systems. • we offer a full-time position in a fast growing company at the cutting edge of • resolving any issues during assembly and testing our systems electron microscopy applications • coordinate with other team members during manufacturing, design and • you will be based in our office at Brussels. software engineers, putting priorities in place • possibility of company car • traveling outside Belgium (Europe, US & Asia) to install our • renumeration and evolution according skills (Fixed + variable ) instrumentation on various electron microscopes (travel activity about • availability: immediate 20-30% of time) • review and resolve customer issues on site or by email/telephone Please send CV and a motivation letter to [email protected]. • actively participate in organization events (meetings, seminars, training) All applications will be treated with strict confidentiality

Professor of Semiconductor Physics JKU Linz announces a faculty opening for a university professor for Research Associate semiconductor physics Closing date: 31 Mar 2021

Applicants for the position must have a venia docendi (habilitation In accordance with § 94 Sec. 2 subpara. 1 of the Austrian The Facility for Rare Isotope Beams (FRIB) at Michigan State degree) or comparable post-doctorate qualifications in the academic PhDPh .studentshipsD studentsh inip sAtomic in Ato Molecularmic, Mole cOpticalular, O andptic aPositronl and Universities Act, the Division of Semiconductor Physics at the University is approaching completion and commencement field. The successful candidate is expected to actively contribute to PhysicsPo (AMOPP)sitron (A MatO UniversityPP) Phys iCollegecs at UC LondonL Johannes Kepler University Linz announces a faculty opening of user operation in early 2022. The FRIB high-power research and curricula at the JKU as well as independently carry out The AMOPP group in Physics & Astronomy at University superconducting linear accelerator has already been for a university professor for semiconductor physics. administrative tasks in support of institute management. Please see: The AMOPP group in the Department of Physics and demonstrated to accelerate ion beams to the design energy http://www.jku.at/professuren for a detailed description of the position. AstronomyCollege Lo atnd Universityon condu cCollegets worl Londond-leadin carriesg rese outarc h covering a wide range of topics such as: of 200 MeV/u to produce rare isotopes. FRIB is poised to be If you have any questions about the position, please contact Univ. Prof. world-leading research covering a broad range of areas in AMO the world’s most powerful rare isotope beam facility, with The Division of Semiconductor Physics at the Johannes Kepler Dr. Andreas Ney, P +43 732 2468 9642, E-mail: [email protected], physics.• Ul tTheseracol dinclude Gase:s and Molecules unprecedented opportunities to study the vast unexplored University Linz invites applications for a permanent professorship and Univ. Prof. Dr. Armando Rastelli, P +43 732 2468 9601, •• AttosecondAttosecon dand, S tstrong-fieldrong Laser physics,and FE Land in tFELera cinteractionstions with potential of more than 1,000 new rare isotopes never before E-mail: [email protected]. position under private law for a professor of semiconductor physics to withmatt matterer produced on Earth. FRIB includes a target facility for the in- flight production of rare isotopes. An Advanced Rare Isotope begin immediately. The appointment is accordance with § 98 of the A salary above the minimum amount (which is currently €74,503.80 Quantum Information •• Cavity optomechanics with levitated nanoparticles Separator (ARIS) will prepare fast rare isotope beams with high- Austrian Universities Act. An evaluation will be conducted after a five- before taxes) as stated in the collective agreement will be voluntarily Quantum many-body systems purity for nuclear physics experiments. year period. offered. •• Low-energy antimatter physics with positrons and positroniumM echanica latoms Systems in the quantum regime The successful candidate is expected to conduct and pursue • We invite Ph.D. graduates to apply for this Research Associate The Johannes Kepler University wishes to increase the proportion of Antimatter, Positron, Positronium, Electron Collisions outstanding high-quality and internationally visible research as well as academic female faculty and, for this reason, especially welcomes •• Molecular physics and spectroscopy position and join the FRIB Accelerator Physics Department. to play a central role in the organization, efficient use and expansion of applications by qualified women. If applicants are equally qualified, •• OpticalBiolog ibiophysicscal Physics and Laser Tweezers The Research Associate will contribute to the commissioning, the new clean room. a woman will be given preference for this position. The university •• QuantumTheoreti cmany-bodyal Physic sphysics of Molecules and Quantum development, and operation of the FRIB by undertaking projects The research activities of the new professor should synergistically welcomes applications from qualified applicants who have physical • QuantumSystems optics and information processing and activities to improve facility performance as measured by strengthen those at the Institute of Semiconductor Physics and Solid disabilities. These applications will be given special consideration. beam quality, intensity, power, purity, and variety. Fu• llQuantumy-funded interfaces,3 and 4 y quantumear Ph.D sensingstuden andtshi matter-waveps are offer ed State Physics. Predominant research activities shall include systems Prospective applicants are asked to submit their application in with potential applications in the field of quantum technologies and/or for UinterferometryK and EU students while scholarships are available Position duties can be adjusted according to the candidate’s adherence to the criteria stated in the job profile including all requested experience, interests, and talents. photonics based on inorganic semiconductors. documentation (CV, application form etc), in electronic form via e-mail Fully-fundedfor oversea 3s andstu d4 eyearnts. PhD studentships are available. The successful candidate will be expected to develop a research to the rector of the Johannes Kepler University Linz: [email protected] For applications details and more information see For more details and how to apply, please visit: by 31 March 2021. If the documents cannot be sent electronically, five For applications details and more information see strategy designed to collaborate on an interdisciplinary platform with http://www.ucl.ac.uk/phys/amopp and e-mail https://brightrecruits.com/physicsworld-jobs/job/research- working groups at the Faculty of Engineering and Natural Sciences as copies are to be sent by postal mail and should arrive at the rector’s http://www.ucl.ac.uk/amopp/ and e-mail Prof Marzena Szy- associate/ Dr. Marzena Szymanska at [email protected]. well as with research groups in Austria and abroad. office no later than one week after the end of the application deadline. manska at [email protected].

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Fine structure and black holes MATLAB SPEAKS Black holes remain a fascinating idea in popular phys- ics while inspiring high-level research. Indeed, the 2020 Nobel Prize for Physics honoured theoretical work on black holes carried out by Roger Penrose and observa- tional results obtained by Andrea Ghez and Reinhard Genzel. In the 1990s, both Ghez and Genzel indepen- dently analysed the motion of stars near our galactic MACHINE centre, some 27 000 light-years away from Earth. They concluded that a supermassive black hole (SMBH) resides there and holds 4 million times the mass of our Sun. Apart from finding unambiguous evidence of its existence, the discovery carries a bonus – the black hole’s extreme gravitational effects provide a new way LEARNING for physicists to explore α, the fine structure constant. Physical theories rely on essential constants such as c, e, ħ and the gravitational constant G, but some physicists argue that unitless constants are more fun- NASA/JPL-Caltech/ESA/CXC/STScI (NRAO/AUI/NSF); Angelich A With MATLAB,® you can build machine learning damental because they are invariant in any system of Within ral change”. Webb however obtained a bigger change, –5 models to make decisions and predictions from measurement. The fine structure constant α – defined multiverse 4 × 10 relative to the value on Earth, in measurements as e2/(4πε c) where ε is the permittivity of free space made in the strong gravity around a white dwarf star. brain images and recordings. Or build them for 0ħ 0 models – is one such pure number, equal to 0.0072973525693. There are theoretical reasons why α should depend early seismic detection and material discovery. It appeared in 1916 when Arnold Sommerfeld added proposing that on gravity. Also last year, general relativity theorist relativity to quantum mechanics and calculated a better our particular Aurélien Hees of the Paris Observatory, along with 13 Use apps to simplify classification and regression, agreement with the observed fine features of the hydro- universe is international co-authors including Ghez, used her data and notebooks to code interactively and share gen spectrum. α showed up again in the 1920s in Paul to measure the effect of the black hole’s gravity on α Dirac’s relativistic quantum ideas, and in astronomer especially (Phys. Rev. Lett. 124 081101). your results. Arthur Eddington’s theory of the universe. Eddington tuned to This is the first measurement of α near an SMBH, predicted that 1/α would be an integer but failed to support life, and the work shows that this approach can more fully make a convincing case (the latest value 137.036 is only examine the connection between α and gravity. Ghez mathworks.com/machinelearning nearly a whole number). α may be established the presence of the SMBH by plotting the Instead, α acquired deeper meaning within quantum additionally observed paths of stars that orbit the galactic centre. electrodynamics (QED), the theory that won Richard significant These paths occurred within the gravitational field Feynman and two others a Nobel prize in 1965. Now because a from the presumed black hole but were distant enough α is understood as determining how strongly electrons to form ellipses according to Newtonian mechanics; and photons couple. It is a key to the electromagnetic small change general relativity was not required. Then a compara- force, which – along with gravity, and the strong and in its value tively straightforward analysis yielded the value of weak nuclear forces – controls the universe. Within would affect 4 million solar masses at an elliptical focus that held multiverse models proposing that our particular uni- the conditions the stars in orbit. verse is especially tuned to support life, α may be addi- To measure α at high gravity, the researchers chose tionally significant because a small change in its value for life to form five stars that came near the SMBH, and also have stel- would affect the conditions for life to form. lar atmospheres with strong spectral absorption lines. In 1937 Dirac asked if the “constants” are really con- Then wavelength analysis gave the value of α at those stant when he speculated that α and G have changed as locales, with small measured deviations of 1 × 10 –5 the universe has aged. Such changes in the constants or less from the Earthly value. Still, the data already of nature could alter the Standard Model of particle yield new insight by supporting the prediction that the physics, and general relativity, as well as modify our change in α is proportional to the gravitational poten- understanding of the history of the universe. Following tial. However, the measurement uncertainties are too Dirac’s suggestion, various researchers have searched large to yield a definitive value for the proportionality for changes in the constants, especially c and α. constant, which according to Hees et al. would help dis-

Since 1999 astrophysicist John Webb at the Univer- tinguish among different theories that incorporate dark Inc. The MathWorks, ©2021 sity of New South Wales, Australia, has sought changes matter and dark energy. in α over cosmic time. He examined light from astro- Hees now wants to observe stars that are closer to the nomically distant sources after it traversed interstellar black hole as they experienced a stronger gravitational dust clouds, which imprints on the light spectral absorp- potential. The spectral analysis will be harder, but tion lines from the atoms in the clouds. Analysing these Hees reckons he can reduce the measurement errors wavelengths gives the value of α at the remote location 10-fold and has requested new telescope time to do so. and therefore in a younger universe, as determined by We should be optimistic that further improvement will the time lag due to the finite speed of light. Webb’s bring new knowledge about α and the universe. early data showed an extremely small increase over the last 6 billion years. But in 2020 he interpreted new Sidney Perkowitz is the Candler Professor of Physics Emeritus, results from 13 billion years ago, when the universe was Emory University, US. His latest book Science Sketches: Looking at only 0.8 billion years old, as “consistent with no tempo- Science from Different Angles is forthcoming

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