<<

the Perimeter spring/summer 2018

Remembering

The riddle of the Sphinx

AI solves quantum challenges

Taming the Langlands program

Editor Natasha Waxman [email protected]

Managing Editor Tenille Bonoguore

Contributing Authors Tenille Bonoguore Erin Bow Mike Brown Dan Falk Colin Hunter Stephanie Keating Robert Spekkens

Copy Editors Tenille Bonoguore Mike Brown Colin Hunter Stephanie Keating Sonya Walton Natasha Waxman

Graphic Design Gabriela Secara

Cover Illustration Center for / M. Weiss

Photo Credits Adobe Stock Mitch Altman Michael Bennett Mike Brown Stephanie Keating Jens Langen John Matlock NASA Jennifer Roberts Photography Gabriela Secara UCSB/Sonia Fernandez

Inside the Perimeter is published by Perimeter Institute for Theoretical . www.perimeterinstitute.ca

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31 Caroline Street North, Waterloo, Ontario, Canada p: 519.569.7600 I f: 519.569.7611 02 IN THIS ISSUE

04/ Goodbye, dear Stephen, Neil Turok 06/ Remembering Stephen Hawking 08/ Three new appointments bolster and , Tenille Bonoguore 10/ Emmy Noether Fellowships expand, Tenille Bonoguore 12/ California connections, Stephanie Keating 13/ The riddle of the quantum Sphinx, Robert Spekkens 16/ teaches itself to solve gnarly quantum challenges, Tenille Bonoguore 18/ Taming the Langlands program, Dan Falk 21/ Slice of PI: My favourite equation

25/ People of PI: Ghanaian trailblazer Prince Osei, Mike Brown 27/ G7 Sherpas hold planning sessions at Perimeter, Colin Hunter 28/ Thanks to our supporters

30/ Remodelling science, Tenille Bonoguore and Stephanie Keating 33/ WGSI: How to build a better future 33/ Upcoming conferences 34/ “Aim high, work hard, and bring your swagger,” Tenille Bonoguore 36/ What’s physics good for? The incredible MRI, Erin Bow 39/ Particles

42/ PI kids are asking: Rainbows, Stephanie Keating

03 NEIL'S NOTES GOODBYE, DEAR STEPHEN

I was an undergraduate in technicalities. Even more wonderful, He declared himself wrong in 2002, when I was fortunate to we became close friends. and gave John an encyclopedia on attend Stephen Hawking’s inaugural baseball but encouraged him to burn lecture as the Lucasian Chair, the There is so much to say about him, it, saying that would be as useful as position held. The it’s hard to know where to begin. It the information which survived an lecture was provocatively titled: “Is the goes without saying that he was a evaporating . He bet me that end of in sight?” brilliant scientist of the very first rank. cosmic would be confirmed by Through a series of -hearted The concepts he formulated and future measurements – unfortunately, vignettes, Stephen explained some of the questions he started to address, we never did settle that one. physics’ greatest advances. He kept many decades ago, are so deep and the audience on tenterhooks to the farsighted that they continue to inspire Stephen loved the idea of Perimeter end, as we awaited his oracular answer the whole . How can and Institute. It was younger and much more to the question. When it came, it was be quantum? What happens of a gamble when I was approached as surprising as it was unambiguous. inside black holes? What principles to become its second Director. Taking Yes, he said, the newly constructed govern the ? I feel we the position would mean leaving theory of , developed by are approaching the answers, guided Cambridge and Stephen behind, so I other theorists, was the answer. All in large part by observations that went rather gingerly to his office to tell that remained was to work out a few were largely lacking when Stephen him and ask for his advice. But when details. I left the lecture wondering if pioneered the field. Even if the details I described Perimeter’s mission – to physics was really over and whether I of some of Stephen’s favourite theories unify quantum theory and should switch to another field. – like inflation and supergravity – – his eyes literally shone. Although he don’t survive, I believe that his basic said he would be sorry to see me go, I Eighteen years later, I joined Stephen as intuition – that could tell he shared my excitement and a Professor at Cambridge. Supergravity will connect beautifully with , would lend his fullest support. Which had not worked out as the ultimate and the combination will answer deep he did, time and time again. theory (but interest in it continues questions – will turn out to be right. to this day). I knew something of First, he lent his name to our new Stephen’s elegant and influential work Despite Stephen’s stature, he never building, the Stephen Hawking Centre. combining quantum theory with gravity became stuck in his ideas. He was And then he visited, twice, despite in the context of black holes and open to questioning everything, to the massive effort and risk involved, cosmology, and I was keen to interact rigorous argument, and to finding because he wanted to see for himself with him and, if possible, to learn new connections. It made working with what this “grand experiment,” as he from him. So I presented a seminar him enormous fun; it was as if all the called it, was like. He loved being on a topic I hoped might pique his physical constraints on his body were here, having scientific discussions in interest – the birth of an inflationary mirrored by a total freedom and power the Bistro, and inviting many of us over universe. I showed how quantum of thought. You always got the sense, to barbecues at his house. He met effects in inflation, like a cosmic when discussing science with him, with everyone – the PSI students, the magician, allowed you to conjure an that in the next 30 seconds, we might scientists, and countless visitors who infinite universe out of a finite one. To change everything. wanted to be introduced to him. my delight, after the lecture, Stephen said he found the ideas interesting He loved speed and risks and jokes. In many ways, Perimeter epitomizes and he wanted to discuss more. Thus And bets! In 1975, he bet Stephen’s aspirations and his vision. He began our work together, spending that black holes did not exist – a believed, as I do, that the astonishing many wonderful afternoons scribbling bet he lost. He bet that simplicity and unity in the universe cries on the blackboard and teasing out the black holes destroyed information. out for simple, principled explanations.

04 The popular theories like inflation and playground, a little boy started yelling, Stephen very graciously (and typically) – which Stephen, like “That’s Stephen Hawking!” We agreed to meet the boy and thumbprint most others, went along with – remain thought no more about it, but the next the books. The photo of the two of them unconvincing and lack compelling day I received an email from the kid’s together is one of my favourites. The evidence in their favour. Physics now dad saying, “Was that really Stephen thing I love about it most is that they’re has, I believe, to return to the basic Hawking in the park?” both wearing the same shirt! Two little challenges and questions that Stephen kids at heart, driven by curiosity and posed in the earliest and most fruitful It turned out that the kid, although only a desire to have fun making sense of phase of his career. There isn’t a better six, had already read five of Stephen’s the world. place in the world for doing so than books. When he told his mom it was Perimeter. In many ways, we have Stephen, she said “it can’t be!” But – Neil Turok taken on his scientific mission at a time he desperately wanted to bring the when other places are either unable books in and have them autographed. or have lost the confidence to do so. Stephen strongly supported the Centre for the Universe we have recently created here, kindly endorsing the Stephen Hawking Fellowship to which we hope to attract an extraordinary young cosmologist.

On Stephen’s very first night in Waterloo, I invited him and his team out to a local restaurant. We shared a lovely, memorable meal together. When I went to pay, I was told that a regular patron (who insisted on remaining anonymous) had settled our bill, as a welcome gift to Stephen. Stephen was delighted, telling me that, on all his travels, such a thing had never happened to him before.

One fine afternoon, during Stephen’s second visit to Perimeter, he and I decided to take a walk in the park behind the Institute. As we walked around Silver Lake by the public

05 Ray Laflamme was a graduate student under Stephen Hawking at Cambridge when he was tasked with proving a theory of Hawking’s. The problem was, the theory turned out to be wrong.

Stephen, although being well known and having an incredible reputation, with many people looking up to him, was a scientist. And science is very democratic. You discuss ideas, and ideas can be right or wrong. The math in theoretical physics tells you what is right and what is wrong. So I slowly, painstakingly, went through the math and showed that the original idea could not work. Fortunately, there was a colleague, Don Page, who had a very similar result to mine. We slowly convinced Stephen, and when he learned that he had made a mistake, he turned around and said, “You guys are right.” He was incredibly gracious. I heard that he wrote letters of recommendation for me saying, “This guy has proved me wrong.”

PSI Fellow and cosmologist Tibra Ali was a graduate student at Cambridge when he came across a rare find.

I was a graduate student at Cambridge when I came Remembering upon Stephen Hawking’s, “Is the end in sight for theoretical our friend physics?”, a bound version of the inaugural lecture he gave as the Lucasian Professor Stephen at Cambridge. It was about 10 pounds or so – way too expensive for my poor wallet Hawking – but I bought it anyway and 1942 - 2018 kept it carefully packed away with my stuff. He was the head of my research group and we got used to seeing him every day. Often at department parties, he would get bored of talking to the bigwigs and just come and hang out with the students. Right before I graduated, I finally got up the courage to go and thank him during a party, and ask if he would autograph the book. In a day or two, I had his autograph on what would become my most prized possession. His secretary had also inserted a photo of him. I love that photo with his impish smile – and a copy of Marilyn Monroe’s biography tucked into his chair.

Imogen Wright was a PSI master’s student when Stephen Hawking paid them a visit.

My mother doesn’t exactly understand what I studied at Perimeter, but she has a massive photo of me chatting to Professor Hawking at my graduation on her wall, and I think that makes her prouder than anything else I’ve ever done. 06 Eugenio Bianchi was a Perimeter when he used loop to re-derive the Bekenstein-Hawking formula for the of black holes. Then Hawking came to visit.

I was in the Bistro having a coffee and Lee Smolin introduced me to Stephen Hawking. Stephen wanted to hear from me about this recent calculation of black hole entropy. I said I was absolutely happy to do that when they were free. They said, “Okay, in 15 minutes.”

I didn’t have time to freak out or over-prepare. I just had 15 minutes to think exactly what I would condense and explain. The first three questions [from Hawking] were very short: “Are previous calculations wrong?”, “Is the area ensemble wrong?”, and then “Which degrees of freedom?” They were precise questions, the kind you would love to get when you give a seminar: questions that would either kill the argument or make it stronger. Then we went on for three hours discussing, and after three hours they said: “Okay, we go on tomorrow morning.” I was absolutely blown away by that.

When I met him that first time, I had the highest opinion one could have of a scientist. Meeting him and having questions directly from him on what I was doing – that’s something I couldn’t top. Many of his questions are still driving my research today.

Holly Hatch was Perimeter’s Conference Coordinator during Hawking’s first Perimeter visit in the summer of 2010, when she was asked to coordinate a day trip to Niagara Falls. It ended up being the first of many memorable interactions.

I first met Stephen in his office at PI, and I quickly realized that he was just a regular person – a parent and a grandparent. His days were full of complex science, but he knew that weekends were for having fun.

The Niagara Falls trip was memorable, particularly getting soaked on the Maid of the Mist while hoping my makeshift poncho-wrap would keep his computer – his main communication system – working. I got to know Stephen and his carers over the next six weeks, and they even watched the Canada Day fireworks from the backyard of my townhouse in UW grad student housing – the only place that nobody would find Stephen!

The most memorable outing we had, though, was to the African Lion Safari in nearby Cambridge. We were in a specialized rental van and I warned the group that we likely couldn’t take it through the infamous monkey section (because they scratch the paint), but they kept insisting. I still remember our van, covered in monkeys, as Stephen’s carers kept rolling down the windows to try to feed them bananas – all while an enormous male lion sunned himself a few feet from the van. They were having the time of their lives, but I was sure that I would be fired as soon as we got home. Instead, I was called into Stephen’s office the next week and asked to plan a return trip so he could bring his visiting grandchildren.

07 Three new appointments bolster mathematics and cosmology

08 rom the depths of space to the WILL PERCIVAL: She left Caltech to take up a position mathematical framework for at the Mathematics Department at the Fphysics, three new appointments ALL EYES ON THE SKY University of Toronto, cross-appointed to Perimeter’s associate faculty are with Perimeter. pushing to uncover big discoveries. Will Percival also got his start in mathematics, and went to work in Her decision to move north of the Cosmologist Will Percival, industry before realizing he wanted border was motivated by more than mathematician and computer to pursue research that was part of research; she was also growing linguistics researcher Matilde Marcolli, a bigger picture than his day job increasingly concerned about rising and mathematician Ben Webster will presented. So he chose the biggest anti-science politics and sentiment in bolster the Institute’s research and picture of all: exploring the universe at the US. strengthen ties to partner universities. the largest scales. Perimeter now has 19 associate faculty “At present, it just feels great to be able cross-appointed with other institutions Now, Percival works at the interface to work and focus on science without in Canada. between observational and theoretical having to keep worrying about that astrophysics and cosmology, with a kind of threat,” Marcolli said. “It is a “These new appointments represent particular interest in galaxy surveys. privilege that people too easily take for a major strengthening of the He has accepted two positions in granted.” Institute’s efforts in cosmology and Waterloo: as the holder of the new in mathematics,” said Perimeter Lazaridis Research Chair in Astrophysics Director Neil Turok. “Both are critically at the and as an BEN WEBSTER: important avenues through which new associate faculty member at Perimeter. EXPLORING insights into fundamental physics are He plans to build a UW research group being gained.” rooted in the strengths of each institute, THE CROSSOVER aiming to tackle some of the universe’s Turok added: “All the direct biggest unsolved mysteries. Webster’s work in pure mathematics observational evidence we have on always seems to cross into physics. physics beyond the Standard Model But observational measurements His joint appointment to the University and Einstein’s theory of gravity comes are only effective if there are good of Waterloo’s Department of Pure from cosmology – for example, on dark theories to test. “To complement Mathematics and to Perimeter Institute , , and the of a good observational group, you take that overlap to the next level. the . Will Percival is a world need a good theoretical group,” leader in learning about fundamental Percival said. “Having the association Webster seeks connections between physics from galaxy surveys, an area between the new group at UW and the representation theory, mathematical poised for major progress. expertise available at Perimeter will be physics, geometry, and . For awesome.” the past decade, his focus has been “Similarly, the new theoretical on the mathematics of a particular frameworks we now urgently need quantum field theory that can be in order to connect quantum theory MATILDE MARCOLLI: described using two different objects, with gravity and the other forces of PUSHING or kinds of algebras. At Perimeter, he nature will require new mathematical can work alongside researchers who frameworks and tools. Matilde Marcolli MATHEMATICAL tackle the same thing from a physics and Ben Webster are two of the most perspective. creative young mathematicians alive, BOUNDARIES working on areas which connect closely “Understanding the mathematical Marcolli’s eclectic research interests relationship between those is a very to theoretical physics. Their presence span mathematics, physics, and will ensure that Perimeter is a hotbed difficult and strange question,” he computational linguistics. She said. “For me intellectually, having the for brilliant mathematical thinking at the already had ties with Perimeter as a leading edge of physics.” opportunity to come to PI was a big, Distinguished Visiting Research Chair big plus. The visitors, the ability to have (DVRC). Indeed, her latest book, conferences, the whole structure – it’s a Noncommutative Cosmology, is based really unique thing.” on collaborations with Perimeter – Tenille Bonoguore researchers during her DVRC visits.

FURTHER EXPLORATION

People of PI: Meet more of Perimeter’s researchers at insidetheperimeter.ca

09 EMMY NOETHER FELLOWSHIPS EXPAND Perimeter’s flagship program to support and promote women is being expanded thanks to funding from the Simons Foundation.

What started as a pilot project to Perimeter’s Emmy Noether Fellowships aspect of the program, said Perimeter support women researchers at pivotal have already brought 23 early- to mid- Faculty member Bianca Dittrich, who career moments is set to become even career researchers to the Institute for chairs the Fellows selection committee. more powerful thanks to a $600,000 extended visits. US grant from the Simons Foundation. “Long-term visits and the possibility of With this three-year funding, the return visits will allow Fellows to pursue program will expand both in size and deeper research problems in these depth: there is scope to appoint more collaborations,” she said. “By providing researchers each year, and past support for bringing family along, it participants will be able to return also allows researchers to come for as Fellows in later years. longer, and thus more productive, visits.” Perimeter will also intensify recruitment efforts in That interaction will not end when the developing countries, Fellows return to their home institutes. establish the Simons “The Simons Emmy Noether Fellows’ Emmy Noether Fellows’ Network will be unique in connecting Network (a peer highly qualified women researchers in resource to forge and theoretical physics across the globe and support ongoing links to Perimeter Institute,” Dittrich said. between Fellows), and host a Simons Emmy Perimeter Faculty Chair Luis Lehner Noether Fellows’ said the support from the Simons Conference. Foundation enables Perimeter to not only engage more researchers The long-term nature of worldwide, but to help deepen the the fellowships – which collaboration networks of each Fellow. allow Fellows to build their collaborations “We are now able to further amplify over time – is a the scope and reach of this exciting particularly powerful program,” Lehner said. “This will impact physics research at the Fellows’ home institutions as well as PI. Science is an enterprise that can only get stronger by ensuring everyone has the chance to contribute to it.”

10 Announcing this year’s cohort

The 2018/19 Simons Emmy Noether walls, in very small magnetic swirls called Sherry Suyu (Max Research Fellows are: skyrmions, and in creating models for Group Leader and Assistant Professor, interacting magnetic nanoparticles to Institute for Astrophysics Ling-Yan (Janet) Hung (Professor, match experiments. – Technical University of Munich): Fudan University): Janet Hung is a Astrophysicist Sherry Suyu uses strong quantum field theorist with a particular Christine Muschik (Assistant Professor, gravitational lensing to shed light on dark interest in quantum entanglement and Institute for energy, , and supermassive the AdS/CFT correspondence. She also – University of Waterloo): Christine black holes. She plans to work closely works closely with experimentalists to Muschik is a quantum information with members of Perimeter’s Centre probe topological order in quantum specialist who plans to launch an for the Universe, and other Perimeter systems. intensive effort exploring quantum researchers. simulations of lattice gauge theories, Valentina Forini (Lecturer, City with an aim to develop new tools for – Tenille Bonoguore University of London): theorist basic science – specifically, quantum Valentina Forini studies diverse aspects simulators – and to provide applications of gauge field theories using the AdS/ for near-term quantum devices. FURTHER EXPLORATION CFT correspondence, and her work has impacted both sides of the string/gauge Phiala Shanahan (Assistant Professor, Find out more about Perimeter’s Emmy correspondence. College of William and Mary): Particle Noether Initiatives at physicist Phiala Shanahan recently perimeterinstitute.ca/research/emmy- Karen Livesey (Assistant Professor, launched a five-year research project noether-initiatives University of Colorado): Condensed into the quark and gluon structure matter researcher Karen Livesey works of nuclei, with a particular interest in in the area of nano-magnetism. She has applying machine learning to numerical particular interests in magnetic domain studies of the Standard Model.

Download your Forces of Nature posters for free at insidetheperimeter.ca

11 California connections Perimeter’s Educational Outreach team partners with the California NanoSystems Institute at UCLA and Environmental Research Advocates to bring science resources to LA teachers.

Los Angeles is a city more likely to to bringing financing and recognition to quantum mechanics to cosmology. conjure up visions of Hollywood stars environmentally sustainable projects. than neutron stars. But physics and the In addition to materials and supplies, arts are not as disparate as they may After visiting Perimeter and seeing its teachers took home pedagogical seem. resources in action at a local classroom, strategies that they can use right away. Avchen knew California teachers and “They loved the new deep science they Philanthropist and activist Denise their students could benefit immensely learned. They could immediately take Avchen, who co-founded Environmental from them. “It’s such a great way to it back to their classrooms – that’s Research Advocates (ERA) with her present the material,” she said. really empowering,” said Greg Dick, husband Terry Avchen, a prominent Perimeter’s Director of Educational environmental lawyer, was inspired to When she got home, Avchen reached Outreach. support science education after seeing out to educational and community budding artists fall on hard without leaders across LA, including CNSI, “These great teachers, the ones who a backup plan. which regularly hosts events for more take their weekends and drive long than 400 teachers in the area. In 2016, distances to come to a weekend “When you’re dealing with the arts, the Perimeter’s Educational Outreach team workshop, are fighting for their students. impetus is creative. You’re absorbing was invited to present a two-day pilot They want the kids to have better lives,” the world around you. And I find that in workshop for 50 teachers. The project said Avchen. “That’s what I’m hoping physics,” said Avchen. was a resounding success and this year our collaboration will do – give kids a the workshop grew into a full-fledged chance. Perimeter does that all over the Now, teachers in Los Angeles are conference. world.” boosting their ability to engage students with science and math thanks In February, 43 educators from – Stephanie Keating to a growing partnership between underfunded inner-city charter schools Perimeter Institute and the California gathered at CNSI, staying overnight at the NanoSystems Institute (CNSI) at UCLA. UCLA campus while they delved deeply FURTHER EXPLORATION The collaboration was made possible into the process of science. Workshops, Find all of Perimeter’s free thanks to the vision and support of ERA, a demonstrations, and activities spanned resources for teachers at global non-profit foundation dedicated the full gamut of , from resources.perimeterinstitute.ca

12 The riddle of the quantum Sphinx Is a category mistake at the root of our troubles with quantum theory? Perimeter Faculty member Robert Spekkens explores what we can learn from Egyptian hieroglyphs.

A scientific hypothesis is compelling to It would not be the first time that a of a spoken language. In retrospect, the extent that it coheres well with other category mistake was an obstacle all of the attempts at decipherment successful hypotheses and with the to progress in science. My favourite under the ideographic fallacy, as it is experimental evidence, as interpreted example comes from the story of the now called, generated only nonsense. through the lens of one’s hypotheses. decipherment of Egyptian hieroglyphs, a No progress could be made until this When these are woven tightly together problem that was known as “The Riddle category mistake was corrected. in a mutually supporting web of ideas, of the Sphinx.” they are rarely the subject of controversy. Egyptian hieroglyphs are one of A question of “how?” For quantum theory – the theory which oldest known writing systems. They describes all of fundamental physics emerged prior to 3,000 BC and were In 1799, Napoleon’s army discovered with the exception of gravity – there is used continuously for more than the Rosetta Stone, which contained a staggering lack of consensus about three millennia. The last person in the the same text in three different writing its interpretation. There are many ancient world who could read and write systems: hieroglyphs, demotic, and proposals for how to do so, but none hieroglyphs likely died sometime in the Greek alphabetic script. Because has achieved sufficient coherence with the 5th century AD. For the next 1,300 scholars knew how to read the Greek the rest of physics to persuade a majority years, every inscription on every tomb, text, they were confident that they of researchers that it is correct. Why temple, monument, statue, or vessel knew precisely what the hieroglyphs not? I believe that it comes down to a that survived from the ancient Egyptian on the Rosetta Stone must be saying. category mistake. civilization fell silent. Nonetheless, the question remained of how they managed to say it. To commit a category mistake is to The category mistake that stymied so take some entity to be one type of thing many scholars’ attempts to decipher The quantum formalism is similar. Even when in fact it is another. In the case hieroglyphs concerned the nature of though we know what it says about of quantum theory, most approaches a glyph. They were assumed to be the relative probabilities of different have assumed that its central entity – the ideograms representing an idea directly measurement outcomes in any given – describes . In my and pictorially, independently of any experimental arrangement, the question view, it actually describes incomplete spoken language, like the symbols of how it manages to say this remains. information about reality. on airport signs. In fact, they were For example, the equations specify the phonograms, representing the sounds statistical correlations that arise for

13 measurements on a pair of systems that one implies updating one’s information Is there any hope of pulling off this are initially prepared together and then about the other. No spooky actions are sort of explanation beyond the Clifford separated, an experiment first suggested required in this case. fragments? Not if we insist that by Einstein, Podolsky, and Rosen in incomplete knowledge of reality must be 1935. To provide an explanation of We now know that there are certain represented by a probability distribution. these correlations, however, one needs fragments of quantum theory – to provide a causal account of how they containing only a subset of the full set This is what is shown by a famous 1964 arise. Is there a causal influence from of quantum states and measurements – “no-go” theorem due to John Bell. one wing of the experiment to the other, which admit of an interpretation where However, we need not insist on this. or is it simply that the pair of systems act every quantum state can be understood Perhaps the complex-valued matrices as a common cause, with no influence as a mathematical encoding of a appearing in the quantum formalism between the wings? probability distribution over a set of provide a novel way of representing deeper physical states. These are called incomplete information about reality. Getting the causal story right is critical Clifford fragments. if one seeks to extend quantum theory This idea is currently being pursued, into new domains, such as Einstein’s and it is already apparent that even , where causal for the sorts of experiments considered structure plays a critical role. More in Bell’s theorem, one can secure an generally, scientific understanding explanation of the correlations in is all about achieving causal terms of a common cause. But it is explanations, not merely a not yet apparent how to make the description of correlations, so approach work for every conceivable it is also critical for achieving experimental arrangement. It is still a coherence between quantum research program. theory and the rest of science. Nonetheless, the nature of the It turns out that the causal evidence against quantum account of this experiment states representing reality, at depends critically on the this moment in time, bears a attitude one takes to the strong analogy to the nature quantum state. of the evidence against the ideographic interpretation of On the one hand, if one hieroglyphs just prior to their takes different quantum decipherment. states to represent different ways the world can be, then because different choices of An ancient challenge measurement at one wing The hero of the decipherment story of the experiment lead to is a Frenchman by the name of different quantum states at Jean-François Champollion. Already the other wing, one must fascinated by Egyptology as a youth, grant that there are causal he went on to study languages, and, in influences from one wing to 1808, acquired a high-quality copy of the other which travel faster than Rosetta Stone the Rosetta Stone inscription. Early on, the . In other words, this he deduced that the demotic text on interpretation leads to “spooky action For quantum phenomena appearing in the stone was just a cursive form of the at a distance” and tension with relativity these fragments, the account of them hieroglyphic text. Parts of the demotic theory. that one obtains in this way is both text had been previously recognized compelling and coherent with the rest of On the other hand, if one takes different to phonetically encode the sounds of physics – for instance, by not requiring foreign names appearing in the Greek quantum states to represent different any faster-than-light causal influences. ways of having incomplete knowledge text, such as the Greek Macedonian Moreover, the Clifford fragments name of Ptolemy, so Champollion of the world, then the different choices contain most of the phenomena that of measurement at one wing can reasoned that this would be true of the are thought to be characteristically hieroglyphs as well. correspond simply to different ways quantum: entangled states, the collapse of updating one’s knowledge of the of the wave function, interference He focused on strings of glyphs that physical state at the opposite wing. This phenomena, quantum teleportation, the were encircled by ovals – dubbed is because the physical states at the impossibility of cloning quantum states, “cartouches” by Napoleon’s soldiers two wings are both determined by a wave-particle duality, and many others. because of the similarity to the shape common cause, so that learning about of their bullet casings. Counting the

14 number of signs appearing there, he and grammatical forms of Coptic. That states of knowledge rather than states of became convinced that the cartouches was his Eureka moment. He sprinted reality. This parallels the discovery that contained the name of Ptolemy across town, burst into his brother’s the glyphs within the cartouches are rendered phonetically. He then found office, shouted “Je tiens l’affaire!” (I have phonograms rather than ideograms. confirming evidence for the phonetic it!), then collapsed out of exhaustion. values he had obtained, in a cartouche For the totality of quantum theory, containing the name of Cleopatra in Champollion’s phonetic reading of there is good reason to believe that a different hieroglyphic inscription that hieroglyphs has stood the test of time quantum states can still be interpreted had an accompanying Greek text. because it has the kind of coherence as states of incomplete knowledge. He found yet more evidence for his with other evidence that makes it nearly Such knowledge is not represented by values by identifying the names of other impossible to dispute: the meaning of probability distributions, but a more Pharaohs in the cartouches of exotic formalism, the precise other hieroglyphic texts. form of which is not yet clear. This parallels the fact that, Incredibly, this progress did not unlike proper names that are lead Champollion to overcome pronounced similarly in many the ideographic fallacy. Instead, different languages, a phonetic he reasoned that it was only in reading of the glyphs outside the exceptional circumstance of the cartouches required of writing proper names that Champollion to identify the they were to be interpreted specific language spoken phonetically. by the Egyptian scribes. For proponents of the research In the early 1820s, Champollion program described above, was still working feverishly on the unearthing the novel formal problem. He was not sleeping language for expressing much and hardly eating. The incomplete information of reality solution continued to elude him – our Eureka moment – is still to until, on a fateful day in 1822, he come. decided to focus on the glyphs A Rosetta Stone cartouche outside the cartouches and see There are many other problems what would happen if he attempted to the hieroglyphic script on the Rosetta in physics for which the proposed read these phonetically as well. Stone is found to match that of the solutions are not yet compelling because Greek text, and similarly for other scripts they are not yet embedded in a web of Bear in mind that it was not known what that have Greek counterparts; the mutually supporting relationships with language was spoken by the ancient contents of hieroglyphic inscriptions fit the rest of physics. For these, the story of Egyptians, and if nothing of it had with their archaeological and historical the decipherment of hieroglyphs should survived, then a phonetic reading would context; and the notion that Coptic is prompt us to reflect more deeply about have been impossible. But something a descendent of the language of the our presuppositions: could they contain had survived. The language of the ancient Egyptians fits both linguistic and a category mistake? Egyptians had continued to be used in historical evidence. the liturgical tradition of the Coptic Christian Church, even after Arabic became the everyday spoken language The lesson for of Egyptians following the Arab conquest of Egypt in 642 AD. As it happened, quantum theorists – Based on Robert Spekkens’ Perimeter Champollion had studied the Coptic Public Lecture on February 7, 2018 For the Clifford fragments of quantum language. So when he attempted a theory, the interpretation of quantum Watch it on Perimeter’s phonetic reading of the glyphs in the states that coheres best with the rest of Youtube channel: rest of the Rosetta Stone, he began to physics is the one that interprets them as www..com/PIOutreach recognize the verbs, nouns, pronouns,

References:

M. Zender, “Writing and Civilization: From Ancient Worlds to Modernity,” The Great Courses (2013).

R.W. Spekkens, “Quasi-quantization: classical statistical theories with an epistemic restriction,” in Quantum Theory: Informational foundations and foils, eds. G. Chiribella and R. W. Spekkens, Springer (2016).

M.S. Leifer and R.W. Spekkens, “Towards a formulation of quantum theory as a causally neutral theory of Bayesian inference,” Phys. Rev. A 88, 052130 (2013).

15 Artificial intelligence teaches itself to solve gnarly quantum challenges Rather than battle it out to obsolescence, new research shows how quantum and classical systems can evolve together.

n popular culture, quantum This pas de deux recently took one just due to the nature of quantum computing is often painted as an more step thanks to a paper published mechanics itself,” noted Perimeter PhD Iultra-powerful technology that will in Nature Physics by researchers at student Barak Shoshany in an answer on first outrace, and then replace, its Perimeter Institute and the University Quora.) classical counterpart. In reality, though, of Waterloo, with collaborators at ETH the two are inextricably linked. Zurich, Microsoft Station Q, D-Wave Why is it worth the hassle? Because this Systems, and the Vector Institute for ability – to know, and therefore exploit, We use classical computation and Artificial Intelligence. a quantum state – is crucial to quantum simulations to develop and design computing. Until we can do that, our today’s nascent quantum devices, which The team applied an artificial intelligence ability to scale the small quantum devices are then nested within a much larger (AI) to a particular problem in quantum that we do have, or manufacture more framework of classical computers. computing: working out the state of a robust quantum computing hardware, quantum device using only snapshots remains limited. The effort to advance these different of gleaned from experimental technologies – which both fuel and rely measurements. Currently, we ascertain the state of on each other – resembles something quantum devices using a process like a dance. Movement is required on This is a gnarly challenge. The state called “quantum state tomography,” or both sides. It takes the best in classical of a quantum system contains all the QST. Using imperfect snapshots of the computing to advance quantum information about that system. However, system as a starting point, researchers capabilities, yet each leap in quantum you can only extract some information mathematically backtrack until they can computation demands more of its at any one time. (“This is partly due to ascertain the full quantum state at the classical partner. the and mostly moment the measurements were taken.

16 This “reverse-” approach is generated from a number of different “Our approach can be used to directly performed with complex that quantum states. validate quantum computers and require a considerable amount of data simulators, as well as to indirectly input and manipulation. It is a significant They started with a standard (but still reconstruct quantities which are challenge because of the huge number complex) system, in which interacting experimentally challenging for a direct of incomplete snapshots required to quantum spins are arranged on a observation.” perform the reconstruction. lattice. This model is used in quantum simulators based on ultra-cold ions Melko and colleagues have already In the paper, “Neural-network quantum and atoms, and its tomography is very put this to the test. In a follow-up state tomography,” Perimeter associate difficult using traditional approaches. paper published as a preprint on the PhD student Giacomo Torlai and The self-learning AI worked. arXiv, the AI was applied to real data. Perimeter Associate Faculty member “The original paper only tackled pure Roger Melko (pictured left), along The team then progressed to increasingly quantum states. We had to account with collaborators, applied the same difficult challenges until they reached for the fact that experiments can be a process, but had a cutting-edge AI one of the most complex things to little more noisy, they can be more dirty neural network do the heavy lifting. calculate: entanglement entropy. and uncontrolled,” he said. “It worked great.” They embraced unsupervised machine Entanglement entropy is associated with learning – essentially, an AI that learns the information that is lost when you It’s one more step in what he expects to for itself. The AI learned how to combine isolate a region to study its quantum be a long and fruitful exchange between the measurements of the quantum properties. By “cutting out” part of the classical and quantum computation. hardware to create its complete system to study, you inevitably leave quantum mechanical description. some entangled partners out of the “In the future, when we scale these equation. This corresponds to missing quantum devices, it’s going to be the “Our only requires raw data information, which corresponds to AI that can watch the quantum system,” obtained from simple measurements entropy. Melko said. “The most adaptive, most accessible in experiments,” Torlai said. efficient algorithms will nurture the “The idea is to build a general and Entanglement entropy provides quantum computers. It’s going to build reliable tool to assist the development important information about interacting, them, it’s going to design them, and of the next generation of quantum many-body quantum systems, and is when they’re running, the AI is going to simulators and noisy intermediate-scale of great interest in condensed matter interface with them.” quantum technologies.” physics and quantum information theory. But assessing entanglement entropy in The key to it all – the music for the dance experiments is fiendishly difficult. – is data. With the right AI and enough Retooling AI data, this work shows that it is possible The team found that the neural network for a general-purpose neural network to In industry, neural networks are often was able to provide an estimate of learn, probe, and analyze a quantum used to mine big data. Torlai and entanglement entropy using simple system, regardless of its theoretical collaborators reversed that dynamic: measurements of density, which are underpinnings. they took an industry-standard neural accessible using today’s experimental network, called a restricted Boltzmann capabilities. “This approach can And that is a good thing, says Torlai. machine, and applied it to theoretical benefit existing and future generations After all, data is an essentially limitless research. of devices ranging from quantum resource. computers to ultra-cold atom quantum It is part of the broader “quantum simulators,” they write. “We are now at a turning point, with the machine learning” program in which possibility of generating large amount theorists and experimentalists use of data with the quantum hardware machine learning to design and analyze Putting it into practice currently operational,” he said. “The quantum systems. data will always be truthful.” Unlike the majority of approaches Torlai, who came to Waterloo specifically designed to understand quantum – Tenille Bonoguore to work with Melko, first used machine hardware – which are tailored to learning to study quantum error the specific regime – the team’s AI is correction for topological quantum platform-agnostic. The neural network, systems. they write, is general enough to be applied to a variety of quantum devices, In this latest research project, he including highly entangled quantum designed the machine-learning circuits, adiabatic quantum simulators, methods to perform neural-network and experiments with ultra-cold atoms QST. The team then performed the and ion traps in higher dimensions. tests using controlled artificial datasets

17 Taming the Langlands program Perimeter researchers are pulling from physics and mathematics to connect two ways of understanding nature, writes Dan Falk.

Almost 400 years ago, Galileo declared This tangle is giving rise to a rich interplay of , the framework that that nature is “written in the language across disciplines, in which physicists accounts for the known forces of physics of mathematics.” Since that time, the can learn from mathematicians, and, (with the exception of gravity). Some of relationship between mathematics perhaps surprisingly, mathematicians its predictions agree with observations and science – especially physics – has can also learn from physicists. That is to an accuracy of one part in 1010. And only strengthened. Unfortunately, the where Davide Gaiotto comes in. yet, there’s still a great deal about QFT universe doesn’t come with a guidebook that remains to be discovered. “We still that explains which mathematical ideas Fittingly, Gaiotto holds the Krembil understand very little of it,” Gaiotto says. can be used to explain which natural Chair in Theoretical He adds, “It’s really hard!” phenomena. Physics at Perimeter. His particular The good news is that Sometimes, the connections mathematicians and physicists are relatively straightforward. are collaborating more than For example, Galileo found ever before – a collaboration the mathematical formulas that was sparked around 20 that govern the motion of years ago, Gaiotto says, when simple pendulum, and of balls (an attempt at rolling down an incline. But a quantum theory of gravity) as the physics gets harder, so first gained widespread does the math. When Newton attention. “In the process, tried to understand how one mathematicians got interested variable changes moment in quantum field theory, and by moment with respect to physicists got interested in another, he found he needed certain mathematical tools,” an entirely new kind of Gaiotto says. mathematics (what we now call calculus; as it happened, Many of those tools involve Gottfried Leibniz developed it something called the at the same time). And when Langlands program. Named Einstein was developing his for Canadian mathematician general theory of relativity, , the he found that he needed to Langlands program involves make use of non- interest is quantum field theory (QFT), proposed connections, or – which, luckily, had been invented a theoretical framework for modelling bridges, between a number of seemingly around 60 years earlier by the German the behaviour of subatomic particles. disparate branches of mathematics. In mathematician, Bernhard Riemann. (As Gaiotto points out, it makes more particular, it suggests bridges between sense to talk about them in the plural, number theory (the study of integers, Indeed, today’s mathematics can be quantum field theories.) especially prime numbers) and analysis so involved that it’s hard to tell if two (an umbrella group of ideas involving branches of mathematics are related The origins of QFT go back almost 100 continuous curves and surfaces, of which to each other, let alone to the physical years, to the first attempts to combine calculus is the best-known example). world. And vice-versa: in some areas quantum mechanics with theories such of physics, we’re still in the process as electromagnetism. Since then, QFTs At first glance, these seem quite different. of discovering which mathematical have proved to be incredibly successful Numbers are discrete entities, while tools are needed and learning how to – and invaluable in describing the real curves and surfaces are continuous; it’s develop them. world. They underlie the Standard Model not immediately obvious why they should

18 be related at all. But Langlands figured are akin to the famous Schrödinger structures in the geometric Langlands we just weren’t looking hard enough. equation, which governs the evolution program, and their relation to physical Back in 1967, when he was 30 years of quantum mechanical systems. objects. They’d managed to show old, he wrote a letter to André Weil, one that QFT predicts the existence of of the mathematical luminaries of the “If you apply the same kind of analysis to such relationships, and that certain time. In the 17-page letter, Langlands [the Langlands program] that physicists mathematical objects would encode the outlined the nature of the bridges as apply to the Schrödinger equation, you properties of particular physical objects. a series of conjectures, urging Weil to get the analogue of energy levels,” he consider them as “pure speculation.” says. “You get discrete numbers.” They also identified which physical He added: “If not – I am sure you have objects were responsible for the most a waste basket handy.” In other words, the mathematicians important mathematical objects on one who have immersed themselves in side of the duality. However, they lacked The waste basket would not be the Langlands program may have a generic method for translating from necessary. Langlands was on to something to offer the physicists who the physical side to the mathematical something. (Earlier this year, he was have been struggling to make sense side, and for working out a physical awarded the prestigious Abel Prize, often of QFT; quite possibly, they can help description of the objects whose considered the mathematical equivalent physicists better understand these exotic existence they’d predicted. of the Nobel.) In fact, mathematicians mathematical structures. have spent much of the past half century Later, in collaboration with Witten, trying to prove the various conjectures Quantum mechanics describes things Gaiotto and his colleagues were that make up the Langlands program; that come in discrete units, like the able to identify these dual physical it is sometimes referred to as a “grand energy levels allowed within an atom. objects, but couldn’t immediately find unified theory of mathematics.” Meanwhile, most physical theories a way to compute the corresponding involve fields, which are continuous. mathematical objects. A key issue is the nature of Anything that can help connect these the connection between these two ways of parsing nature could pay off “For me, the puzzle was that I had these mathematical structures and the in the world of particle physics. quantum field theory configurations, physics of quantum field theory. which clearly had implications for the What, exactly, does it reveal about the For Gaiotto, the key idea is something Langlands program,” says Gaiotto. “But physical world? called the geometric Langlands duality I could not do calculations with them, – a reformulation of the original and that bugged me.” He says that last “They [the mathematicians] are still bridge conjectures expressed in terms year he finally had the tools needed far from being able to understand of algebraic geometry (the study of to “sidestep the main computational quantum field theory completely,” complex, non-Euclidean structures). In obstruction,” as he puts it. His Gaiotto says. “But at least they’re 2006, of the Institute for breakthrough revealed the connection already learning to do calculations Advanced Study and Anton Kapustin between the physical and mathematical that the physicists didn’t know how of Caltech discovered a connection structures. And with that, he was in a to do.” The mathematicians are also between the geometric Langlands position “to do actual calculations.” getting something in return: “They’re duality and S-duality, a property of slowly coming to accept this idea that certain quantum field theories such The breakthrough involved applying quantum field theory is a big lump as supersymmetric gauge theory.1 to the problem. of knowledge that is waiting to be (S-duality is somewhat analogous to Vertex algebras, Gaiotto explains, are unpacked.” the connection between electricity and like Rosetta Stones that can help the magnetism, explains Miroslav Rapčák, mathematicians and the physicists Jim Arthur of the University of Gaiotto’s PhD student: if you swap understand each other. Gaiotto showed Toronto, one of Canada’s leading electrical and magnetic charges, the that calculations involving physical mathematicians and a former student mathematical structures stay the same. objects could be treated as vertex of Langlands, agrees. “To me, it seems S-duality is like a supersymmetric version algebra calculations; he created a there’s a very striking analogy between of that.) “dictionary,” as he puts it, for “mapping the Langlands program and quantum physical objects to vertex algebra mechanics,” he says. Gaiotto’s work builds on what Witten objects.” and Kapustin had begun. Witten and The equations that crop up in the Kapustin had been investigating the The result sheds a light on “a web of Langlands program, he suggests, dualities that link various mathematical mathematical dualities, which extend

1 Supersymmetry (SUSY) proposes a relationship between two basic classes of elementary particles: bosons, which have an integer-valued , and fermions, which have a half-integer spin. In supersymmetry, each particle from one group would have an associated “partner” particle in the other, the spin of which would differ by a half-integer. These super-partners have not yet been observed in nature. Gauge theories are a class of quantum field theories in which the variables that describe the field remain unchanged, or invariant, under certain transformations. This property gives the theory a certain symmetry, which in turn restricts how the field can interact with other fields and particles. A supersymmetric gauge theory is a theory that’s consistent with supersymmetry, and which also has internal gauge symmetries.

19 and clarify the original geometric With geometric Langlands now at least all of it applies to the universe we live Langlands [program],” he says. partially tamed, Gaiotto hopes the in. It may very well be that only some collaborations between mathematicians parts of the Langlands program will It’s a significant breakthrough, according and physicists will continue. “I see very bear fruit that turns out to be relevant for to those who work in the field – “quite fruitful developments in the future, in physicists. But Gaiotto’s okay with that. spectacular,” as Witten describes it. the interaction between physicists and “He has made remarkable progress in mathematicians,” he says. After all, “Personally, I’m interested in quantum understanding the geometric Langlands the mathematical structures he’s been field theory as its own subject,” he says. correspondence,” Witten said by email. exploring are very rich; there’s much “At this point, I like it enough that, even “It is amazing to me how he has been more out there waiting to be discovered. if it didn’t have any applications to able to bridge the gap between what It’s like those old maps from the Age of physics, I would still pursue it. The fact could be understood by physics-based Exploration, he suggests. “There are a that it has applications to physics is an methods and what the mathematicians bunch of trade routes that you’ve been extra bonus.” are able to appreciate.” following, a few pieces of land that you understand, but 99 percent of the map Gaiotto’s work has attracted widespread is just sea monsters.” interest, and was the focus of a three- day workshop at Perimeter in May, titled He also hopes that more light will be “Gauge Theory, Geometric Langlands, Dan Falk (@danfalk) is a science shed on quantum field theories. That’s journalist based in Toronto. His books and Vertex Operator Algebras.” Witten tricky, though, because the mathematics and other leading specialists were in include The Science of Shakespeare is very rich, and – Galileo’s dictum and In Search of Time. attendance. notwithstanding – it’s far from clear that

Physics rocks.

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20 My favourite equation

We all have our favourite things. Physicists explain the universe through the symbolic language of mathematics, so it makes sense that they have special fondness for certain equations. We asked scientists to reveal which equation stole their heart, and why. Here are seven – you can find more at insidetheperimeter.ca

Natalie Panek Rocket scientist, MDA Corp. “This equation inspired me to write a high school research project on using rotation curves of galaxies to estimate the amount of dark matter in the universe, which introduced me to the inspiring work of . That paper was the launch point for my career in aerospace.”

21 Pedro Vieira Theoretical Physicist, Clay Riddell Chair at Perimeter Institute, and Visiting Professor at the ICTP South American Institute for Fundamental Research “Our best definition of quantum gravity in a box (in AdS) is given by quantum field theory without scale (the CFT). This works amazingly well for toy models, simplified theories used as theoretical physicists' playgrounds. Is this also how the universe works?”

Emily Levesque Astronomer, University of Washington “The luminosity-radius- relation for stars is a deceptively simple equation: it demonstrates that a star’s luminosity increases with both its radius and its temperature. Because of that, it’s very elegant and easy to understand.”

22 Rob Moore Assistant Director, Stanford Institute for Materials and Energy Sciences “I can’t think of another equation that has had a more dramatic impact on our history and our world. So much of what we have built around us started with knowing F=ma.”

Sean Carroll Astrophysicist, Caltech “Ludwig Boltzmann’s definition of entropy appears on his tombstone. This deceptively simple equation relates the underlying macroscopic world to the emergent world of our experience, and helps explain the arrow of time. Also, having an equation on your tombstone is pretty gangster.”

23 Ethan Siegel Astrophysicist, Lewis & Clark College “The first Friedmann equation describes how, based on what is in the universe, its expansion rate will change over time. If you want to know where the universe came from and where it’s headed, all you need to measure is how it is expanding today and what is in it. This equation allows you to predict the rest!”

Marina Cortês Cosmologist, “The second law of is both profound and mysterious. As the great quote by says, you can escape any laws but ‘if your theory is against the second law … there’s nothing for it but to collapse in deepest humiliation.’”

24 People of PI: Ghanaian trailblazer Prince Osei

After obtaining the first PhD in mathematics granted by the University of Ghana, Prince Osei rince Osei’s path to academia has been marked by a stubborn, almost pathological, avoidance of what is tackling complex problems in Pothers suggested he do. quantum gravity and setting an Now, as a researcher tackling some of the most difficult problems inspiring example for the next quantum gravity has to offer, his instincts have proven correct and his example is motivating other aspiring mathematical physicists in generation. his native Ghana.

Growing up in Akim Oda, a small town in the eastern region of Ghana, Osei spent much of his time playing football in the streets or going hunting. When he was only 10 or 11, his father – an accountant at the local secondary school, as well as a farmer – feared he was becoming troublesome and sent him to boarding school in Ghana’s capital city, Accra, to “become proper.”

25 Suddenly separated from his family, A chance meeting Osei. “I had a lot of ideas in my head Osei had to learn to do things for and I was looking for the time to get himself, including fending off bullies. Toward the end of his master’s, Osei away and work on those ideas, and this He found it difficult settling in, but had a chance meeting with Bernd was the perfect environment for me to emerged with a deep-rooted sense of Schroers, a professor from Scotland’s do that.” independence. Heriot-Watt University who also works on quantum gravity. While vacationing In junior high school, Osei’s math in West Africa, Schroers showed up in A new quantum hub teacher put a simple equation on the the University of Ghana’s mathematics board and asked someone from the Those ideas largely concern quantum department during a discussion on algebra and an algebraic approach class to try to solve it. Osei volunteered, differential equations. After chatting but made a mistake in his solution. to problems in quantum gravity – in with Osei, Schroers asked to see his particular, the role of quantum groups master’s . “He put me in front of the class in noncommutative geometry and and told me that, if I can’t solve this “He stood out there in the and topological quantum field theory. problem, I can’t go anywhere, and he was flipping through, and we were He’s also recently been interested that I’m dumb,” remembers Osei with talking,” says Osei. “After looking a laugh. “That night, I said, ‘No, I’m in topological quantum computing, through for a while, he asked me, ‘Do because of its relation to quantum going to prove to this man that I am you mind if I supervise your PhD?’” not stupid.’ I got out all the math books gravity. It’s an area he will be able to at my disposal and I read a lot.” This might seem a serendipitous explore more in his new role as the encounter, but Osei politely declined. Project Developer of Quantum Leap He also sought help from friends who Most of his colleagues had gone to Africa (QLA). Based in Kigali, Rwanda, were stronger students, even bribing North America to earn their PhDs, and QLA is an information science and one with food in exchange for tutoring. that’s where he envisioned himself quantum technology hub created by “At the end of the term, I got higher going as well. AIMS to deliver high-impact research in marks than he did,” laughs Osei. big data analytics, quantum computing But Schroers, it turns out, is a little and quantum information technology, Top marks became something of a stubborn as well. It took months, many and smart systems design. theme. Osei finished junior high at the emails, another visit to Ghana, and a top of his class and elected to go to the trip to Edinburgh for a workshop on “The idea is to set up a world-class country’s best high school for science, quantum gravity and noncommutative research centre in Africa,” explains pleasing his father, who hoped he geometry, but Osei eventually agreed Osei. “Africa missed the Industrial would go to medical school. The only to work with him. Revolution. We missed the Digital problem? Osei hated biology. “I had to Revolution. But there’s a Quantum make a conscious effort to make sure Between 2009 and 2012, he spent Revolution on the horizon and we don’t I was getting low marks in biology and three months per year in Edinburgh, want to miss it. The idea is to set up this 90-100 in math,” he recalls. “At the as well as a little time at the African new research centre to, in fact, lead the end of the term, I showed the report Institute for Mathematical Sciences Quantum Revolution.” to my dad and told him, ‘Look at the (AIMS) in South Africa and at Perimeter biology. I am not good. I am not doing Institute, but most of his time was spent For now, Osei is just excited about the well. Look at math! I’m excelling.’” at the University of Ghana – a school opportunity at QLA, but he ultimately that had not awarded a single PhD wants to return to his native country Osei ultimately convinced his father of in mathematics since its founding in and help build up the mathematics his preferred path and began studying 1948. department at the University of Ghana. mathematics at the nearby University Last year, four years after Osei obtained of Ghana, taking some courses in “I was the first PhD [in mathematics] his PhD, the university conferred three theoretical physics as well. He stuck to be awarded by the university after more PhDs in math. around for a master’s degree, settling 65 years,” says Osei. “Before I got my on quantum gravity as his area of PhD, the youngest person with a PhD “There are lots of young people focus after searching online for the in the department who was Ghanaian behind me who have been inspired,” most difficult unsolved problems in was 65 years old.” says Osei. “The aim is to just focus . on my assignments and try to achieve After spending three years helping to my goals, and then definitely it will “Getting stuck and struggling for a long build AIMS-Ghana as its Academic naturally encourage.” time and finally ending up with some Director, Osei arrived at Perimeter in nice result is satisfying,” explains Osei. August 2015 via the Fields-Perimeter – Mike Brown “I enjoy studying mathematics. I get Institute Africa Postdoctoral Fellowship. excited. I shout when I get nice results.” A year later, he became a full-time postdoctoral researcher. “I had always wanted to have some time here,” says

26 G7 Sherpas hold planning sessions at Perimeter

In preparation for the 2018 G7 Summit in , representatives from each G7 nation assembled for two days of planning sessions.

In the ascent toward the 2018 G7 said Peter Boehm, who is the Deputy During a break from their private Summit, Perimeter served as base camp Minister for the G7 Summit and the sessions, the Sherpas met and talked for representatives of world leaders personal representative of the Canadian with Perimeter researchers and students from each of the Group of Seven (G7) Prime Minister. from their home countries. nations. The G7 Summit is an annual gathering Neil Turok said it was an “honour and a In January, the personal representatives where leaders of the Group of Seven privilege” for the Institute to be chosen of leaders from each of the G7 nations democracies address global issues and as the site of the planning sessions. gathered at Perimeter to plan for this opportunities to advance economic year’s Summit, to be held in Charlevoix, prosperity, equality, diversity, and the “Our task is to bring the brightest minds Quebec, in June. path to a more sustainable future. together, from around the world, and give them the opportunity and the Perimeter, the organizers said, Several months prior to the Sherpa challenge to interact, collaborate, and exemplifies values underpinning their meeting, Perimeter Director Neil Turok solve important problems,” Turok said in discussions: collaboration, openness, and Founder shared a recorded greeting to the guests. diversity, and the power of big ideas. ideas with Boehm on topics related to the G7, particularly regarding access to “A marvellous future awaits, if only we “Perimeter Institute is world-renowned. excellence for brilliant young people, the can take care of ourselves and our There are researchers here from all over advancement of women, and building planet. We are relying on you, and our the world and it is a beautiful setting in capacity in skills that will help drive the global leaders, to show the necessary which to have a meeting of this kind,” wisdom.” future economy. – Colin Hunter

27 THANKS TO OUR SUPPORTERS

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$25,000+ $10,000+ Robin and Robert Ogilvie Emmy Noether was a brilliant scientist whose Bosch Community Fund, on The Boardwalk Ildiko and Peter Paulson work underpins much of modern physics. behalf of ESCRYPT in Canada Perimeter’s Emmy Noether Initiatives – funded Harbir and Monica Chhina Robert and Pearl Radnitz** Donald and Eleanor Seaman by Emmy Noether Circle donors – support and The Kitchener and Waterloo Reid Family Family Foundation encourage women in science. Community Foundation The TRH Foundation - The Musagetes Fund - The John A. Pollock Alex White FOUNDING DONOR Family Fund The Bluma Appel Community Trust MAJOR GIFTS FRIENDS (UP TO $9,999) The Simons Emmy Noether Fellows Program at Perimeter Institute ($600,000) $5,000+ $1,000+ Stefan and Kate Inglis Shani Pregelj $100,000+ Jerome Bolce Debbie and Ian Adare Sheri and David Keffer W. Michael Roche Anne-Marie Canning Mary and Ted Brough Dan and Robin Robert G. Lake Schnurr Family Dr. Scott and Sherry Vanstone and family Benson Catherine Little Compugen Inc. Foundation Neil Bresolin George Meierhofer** $25,000+ J. DesBrisay Lewis Warburg and M. Cannell Douglas Brock Foundation** L. Elizabeth Quinn Linamar Corporation Michael Duschenes The Carson Family Jiecheng Zhang Neil Steven Rieck $10,000+ Foundation Dorian Hausman Burgundy Asset Management Ltd. $250 to $999 Nancy Ruddell David Cook Robert Korthals Chelsea and Keegan Stairs Master LTD Patrice E. Merrin and Janet Charlton Ben and Mona Davies Arnott Toyota Motor $5,000+ Stephen Lister Greg Dick John Attwell Manufacturing Canada and Dr. Molly Rundle Andrew and Lillian Bass Edward Goldenberg (TMMC) Mike Birch Renée Schingh Mark Caplan and Claire Angus Ed Kernaghan Kim Tremblay and Robert Myers Matt Douglas Jennifer Scully-Lerner** Frederick Knittel Jacqueline Watty Chris and $2,500+ $2,500+ Carol A. Lee Chryssa Geddes Natasha Waxman Don Campbell Maria Antonakos and Harald Stover ODC Tooling & Molds Jane G. Hill Gerry Wisnoski Michael Horgan in memory of Leejay Heather and John Clark Stephanie, Robert, … plus 6 anonymous Julius Levene John Matlock and Aaron Hilson Friends donors $1,000+ Doug Powrie Colin Hunter Andrea Grimm and Sandra Herd Beth S. Horowitz GIFTS OF CELEBRATION, HONOUR, AND MEMORY Lisa Lyons Johnston Vicki Saunders Carolyn Crowe Ibele, in memory of Dr. Richard A. Crowe David Tovell Simon Haysom, in memory of Elsie Haysom Steven and Suzan Wilson - Rebel Homes Inc. $250 to $999 IN-KIND SUPPORT John Attwell Jeremy Bell and Sunny Tsang Shaw Communications Alexandra Brown Steinway Piano Gallery Toronto Marsha Eberhardt This list reflects gifts received between August 1, 2016 and March 31, 2018, and multi-year KPMG Management Services LP commitments of $50,000 and more. Nicholas Reaburn Perimeter Institute (Canadian charitable registration number 88981 4323 RR0001) and Friends of Betty Robinson Perimeter Institute Inc. (United States EIN 05-0553637) are charitable organizations devoted to fundamental physics research, training, and educational outreach. Barbara Dale Vaillancourt ** Supporters of Friends of Perimeter Institute Inc. Sonya Walton 29 29 REMODELLING SCIENCE.

Researchers are seeing cracks in the structure of science. The solution, they suggest, could be to create a new, open-plan approach with room for everyone.

Ask a young researcher what is most A recent gathering at Perimeter Institute payoffs. Compounding these issues frustrating them right now, and they aimed to give that effort a boost. The is the increasing complexity of science might not point to a complex formula or three-day “Open Research” conference itself. an intractable theory. Rather, many are brought together 30 scientists, vexed by something much larger: the designers, and entrepreneurs to map By removing impediments that keep structure of science itself. out an alternate, open reality, and to people out of research or muddy the identify paths that could lead there. flow of ideas, Smerlak believes that As society embraces the likes of open science could become more global and data, makerspaces, and collaborative For co-organizer and physicist Matteo innovative. “A lot of science is really processes, the historical foundations of Smerlak, this is not an esoteric issue. knowing what the good problems are. science – university departments, pay- His cross-disciplinary work intersects It’s not only the skills and it’s not only the walled journals, group membership with several specialties, which means data; it’s being part of a conversation – are starting to feel increasingly out- he’s often facing a steep learning that is contemporary and alive,” he said. dated. curve. For established research, one can turn to books and monographs, Despite their brilliance, researchers A growing number of scientists argue but few authoritative resources exist for in developing countries are too often that changing not just how we do cutting-edge topics. People must instead limited to working on old problems, he science, but how we share it as well, rely on a flood of research papers – said. Much cutting-edge work begins would unlock vast new opportunities. many of which can be overlapping or as a conversation at a conference or This new kind of science, they envision, contradictory. In recent years, that flood institute. If you’re not physically there, would be open in both process and in has become an unruly torrent thanks to or are not already on the radar of those practice. the proliferation of online journals and involved, you’re left out of the loop. the concurrent rise in predatory journals. Other fields have already embraced “We have the internet now,” said the ethos of openness: “open software” Meanwhile, the “publish or perish” ethos Smerlak. “There should be ways to (think Linux and GitHub) is now well of academia means young researchers open up the problems as they are entrenched after arriving on the tech feel pressure to devote crucial years being invented or raised, and make scene in the late 1980s, and “open to creating a publishing track record. that open to external contributions. innovation” is on the rise. “Open This often means sticking to “safe” There’s expertise out there that we’re not science,” however, is only now starting incremental science that’s likely to be leveraging.” to gain traction. publishable, and eschewing riskier work that could lead to bigger scientific (Perimeter Institute’s PIRSA database

30 is trying to close that gap by sharing everyone to come help solve it, we handful of people, some refurbished lab cutting-edge lectures and discussions find that problems are solved quicker, equipment, and a basement squat. for free.) errors are remedied quickly, and science moves forward at a faster rate.” The years that followed produced But getting scientists to take the plunge extraordinary results. The first project into open research – particularly in fields This doesn’t just impact new and – created during the European horse where data is typically protected, such emerging projects. One of the key meat scandal – was a cheap genetic as biology – is like waiting for the first challenges for open science – and one diagnostic test to determine types of penguin to dive off an ice floe, said of its greatest promises – is finding a meat. Next came a collaboration with Benedikt Fecher, head of “knowledge way to connect people to science that is the State University of New York (SUNY) dimension” research at the Alexander already under way. The more people we to work on biodegradable electronics; von Humboldt Institute for Internet and can connect, the better off science will a project to produce ink using bacteria Society. be, says Simon DeDeo, who runs the instead of petrochemicals (which was Laboratory for Social Minds at Carnegie spun off into the startup Pili); and a While penguins are afraid of being Mellon University. NASA-funded project to design a low- eaten by a shark, scientists are worried cost, open-source bioreactor. that others will use their data to publish “Every scientist in the developed world – first (and thereby get ahead in the race Canada, the United States, certainly in “When we opened the lab, I was for tenure or grants), or that they won’t Europe – we constantly get emails from expecting mostly biologists to come, but receive adequate credit for their ideas. young scientists in places like India and most of the people were non-biologists. That can make people who otherwise China, who are seeking to connect with They were people that wanted to do support the idea of open research the kind of science we do here,” DeDeo biology but never could,” he said. reluctant to then follow through on it, said. Fecher said in his workshop presentation. In 2014, La Paillasse moved to official “Those kinds of connections, that premises in central Paris. A year later, “There is an ideal of openness, and still democratization, that globalization of it partnered with pharmaceutical a space to identify where it’s really worth science, cannot be sustained by a model company Roche to launch the it and relevant,” he said. that was produced or really invented in Epidemium program, using big data 1830.” to analyze cancer epidemiology. More Complexity demands Science has been through such revolutions before. In the late collaboration 1600s, the Royal Society of Science is becoming more complex, and was founded, with the so are the problems scientists are facing. motto “nullius in verba” (take From astrophysics to epidemiology no-one’s word for it). This built to , the volume of on the Republic of Letters and data streaming in from experiments is encouraged the sharing of opening windows on complex problems ideas. Then came the rise of the humans couldn’t tackle in the past. journal, and with it the drive to publish results. Where scientific advances used to be made by individuals or small teams, “We have a sense that we need the complexity of today’s breakthroughs something new,” DeDeo said. Thomas Landrain in the early days of La Paillasse. requires global collaborations, said “One of the big challenges, and conference co-organizer Bapu Vaitla. one of the big opportunities, for than 300 people took part, most of us to solve is not just open data, not them professionals working outside of As a research fellow at Harvard just free access to publications, but a science. One leading project was done University’s T.H. Chan School of Public larger question of how do we rethink by a team of data scientists who work Health, Vaitla explores the linkages collaboration, how do we rethink st in a bank. Another involved Marthe between two extremely complex the openness of science for the 21 Gautier, the long-retired co-discoverer century?” systems: ecosystem health and human of Down syndrome. health. It’s heavily collaborative work that encompasses everything from “We’re not talking about citizen science,” theoretical modelling to marine science. Startups on the scene Landrain said. “With citizen science, you have to over-simplify a problem to “I think the acceleration of scientific Thomas Landrain has seen the impact of open research first-hand. He’s a synthetic make it affordable for people to play progress is strongly dependent on our with it. Here, we bring the raw aspect ability to create cooperative networks,” biologist who started an underground “hacker space” lab called La Paillasse of research in its complexity. Whoever he said. “By democratizing the wants to come at it, then come at it.” awareness of the problem and inviting during his PhD, starting out with a

31 It didn’t matter to the La Paillasse Everything is based on open data; devoted their careers to assembling founders how rigorous the science everything you produce is open source. particular datasets are hesitant to openly was. The point, he said, was simply to We make it clear that we’re not going to share them. challenge themselves and to work out pay anybody, but we’re going to provide what infrastructure is needed in order to you the chance to have fun and learn, It’s mostly young researchers who are do research and produce innovations. and to be able to express your talents or pushing for change, said Vaitla. “From So far, it’s led to robust results. “Every imagination.” this conference, the main takeaway for time we tried to work in a community me has been that, more than creating manner in a very open, collaborative In the push towards open research, tools, the real bottleneck to spreading state, it worked marvellously well,” he there is also a danger of inadvertently open science is about shifting the said. propagating one of the thorniest norms,” he said. issues plaguing science today: its lack Landrain has now launched Just One of diversity. As University of British Perhaps surprisingly, Vaitla sees Giant Lab (JOGL), a research and Columbia microbiologist Rosie Redfield theoretical physicists as particularly innovation lab that aims to partner with pointed out, those who make the norms well placed to help lead the charge. academia, corporations, foundations, shape them. “Theoretical physicists don’t deal as and non-profits to tackle massive social much with datasets in the general sense and environmental issues. He sees the Today’s science tends to favour a certain that we understand them, as do other efforts as a complement to – not a kind of person: privileged, educated, fields. The sharing of data is less of a replacement for – academia. first-world, often white, usually male. concern,” he said. (For example, a recent paper in Nature “We need academic researchers, we Communications showed that women do “I think theoretical physicists in particular need professional researchers. [But] that not get the same speaking opportunities can be an interesting vanguard for this monopoly should not be there,” he said. at conferences.) Without more diversity movement because they can identify a “Knowledge is infinite, so why not have at these nascent stages, there is a risk subset of problems that are perhaps a also an infinite number of researchers?” that the same biases will be baked little bit easier to solve and create some into whatever tools and processes are momentum around.” created for open research. The need for cohesion For Smerlak, the “Open Research” Redfield – who keeps a blog detailing conference was a small first step. All JOGL is just one of the organizations her lab efforts, and was the only woman participants recognized that much work already moving into the open-research presenting at the three-day conference lies ahead if their vision is to come space. Conference attendees also – says higher diversity does not require to fruition, but both academics and included representatives from various lower scientific standards. It just requires startup founders seemed eager for the knowledge-sharing and open-research awareness and vigilance. challenge. The conference attendees startups, including Open Parallel, CTRL plan to produce a white paper from their Labs, and Knowen. “You have to counteract your intrinsic, discussions, in order to prompt further implicit, unconscious biases,” she said. discussions and actions. These early, tangible forays into open “This isn’t a male thing. We all have research can be seen as a promising these unconscious biases. It’s just that “Whether you look at this from a endorsement of the idea, but they pose women are more aware of how women distance or you’re trying to make it issues as well. are being harmed by those biases, and happen, there’s a strong desire to come we are working harder to overcome together,” Smerlak said. Without a dominant platform, the them. scientific community risks splintering “Open-source software is driven by among a dozen or so technologies. If “It’s not enough to be well meaning. It’s a philosophy that’s quite explicit and so, the barriers between platforms would not enough to be well intentioned. You broadly shared by the main actors in the defeat efforts towards collaboration. have to actively work on yourself.” field. Scientists have had a philosophy Researchers will remain in silos, of sharing ideas, being skeptical, separated by technological walls and reproducing results, trying to falsify limited awareness of each others’ work. Dividends are mostly results. There’s no reason to think that we couldn’t have a common philosophy Who pays for open research is another for the young when it comes to open research.” unsolved question. Right now, most So far, the most vocal pushback to open researchers also teach or work in – Tenille Bonoguore research has – as would be expected – industry. At Landrain’s labs, researchers and Stephanie Keating are volunteers, relying on their day come from the establishment. jobs to make a living. “People do it Journals don’t want to relinquish their benevolently because they know it’s control over scientific communication, FURTHER EXPLORATION going to be useful for the greater and the massive profits that come with good,” he said. “There is no exclusivity. it. More senior researchers who have Watch the talks at pirsa.org/C18005

32 UPCOMING CONFERENCES

Asymptotic safety in a dark universe June 5-7

Path to kilohertz gravitational-wave astronomy June 11-13

Low energy challenges for high energy physicists III How to build a better future June 18-21 In 2015, the United Over three days of it can provide a long- Nations established a discussion and debate, term vision for Canada Tri-institute summer school global set of sustainable they devised a robust, and its people,” the on elementary particles development goals community-focused Communiqué notes. (SDGs) to end poverty, ecosystem that could July 9-20 protect the planet, and support and promote the Visit wgsi.org/generation- ensure prosperity for all by 17 SDGs. Together, they sdg/summit-recap to read Foundations of 2030. The challenge now created the Generation the Communiqué, watch quantum mechanics the keynote presentations, is to turn those goals into SDG Communiqué, July 30-August 3 action. a preliminary set of and follow the project’s recommendations, with a progress. At the 2018 Waterloo white paper to follow in Higher algebra and The Waterloo Global Global Science Initiative 2019. mathematical physics (WGSI) summit, held in Science Initiative is a April, a diverse group “Mobilizing Canadian partnership between August 13-17 spanning disciplines, society by building Perimeter Institute and the sectors, and generations stronger and more University of Waterloo. gathered to chart a course equitable communities towards implementation will not only help us in Canada and abroad. achieve these targets, Conferences are continually being added. Check perimeterinstitute.ca/ conferences for the latest.

33 “More women in science today means “Aim high, work hard, more women in science tomorrow. That’s not only and bring your swagger” good for women – it’s good for society.” “Inspiring Future Women in Science” delivers bold dreams and reality- – Mona Nemer, Chief Science checks for science-loving teens: the world Advisor, Government of Canada is full of possibilities, but you’ll have to work hard for them.

How does one become a scientist? But so, too, was the message that STEM is Then she enrolled in science at It’s a simple question with a complex for everyone. During keynote speeches, university, and flourished again. Slowly, answer. Much like the process of science a panel discussion, and a “speed she gravitated more and more towards itself, the route from student to STEM mentoring” session with professionals chemistry, and ended up pursuing her professional is often punctuated with across the STEM spectrum, the message PhD in therapeutics. But that was not the serendipity, intuition, wrong turns, and was loud and clear: passion and end of the story. the occasional Eureka moment. perseverance can take you a long way. “Throughout my PhD, this question was Leading astronomer Emily Levesque had still plaguing me: ‘What are you doing to choose between her love of the stars Keep doors open with your life?’” she said. and her love of the violin. Jesse Popp studied to be a veterinary technician Eugenia Duodu is a chemist. She also “I still didn’t know. A common myth is that before realizing it was a passion for grew up in a low-income community in your path is clear – you know because biology that got her out of bed each Toronto, where her only ideas of being a you’re studying something. But I was still day. General surgeon Monica Torres scientist involved being old, male, and very much involved in my community. had to completely re-do her medical white. For a long time, I felt like these worlds training when she came to Canada [science and community] had to be While she loved science, she didn’t from Colombia. And mechanical separate. I was putting science in a box, consider it seriously until she took a bio- engineer Martha Lenio built an eclectic and I was putting scientists in a box.” tech class at high school. “I killed it, and career around the hope of becoming an I loved it. I started to feel very confident,” astronaut. (She’s still working on it.) In the end, she has combined her she said. Yet her guidance counsellor passions as the CEO of Visions of When 200 young women gathered to advised her against a science-heavy Science, a non-profit that provides celebrate International Women’s Day course load, cautioning that it might be STEM outreach to youth in low-income at Perimeter Institute’s “Inspiring Future too hard. communities. Women in Science” (IFWIS) conference With her mom’s adamant support, in March, uncertainty and ambiguity “The ways I was solving things in the Duodu enrolled in those high school were common themes. lab was applicable to how we can solve science courses anyway, and flourished. things all over the world,” she said.

34 “You can be many things. All of the means they won’t close doors before She can attest to the variety of components of yourself, you bring to the they need to. opportunities engineering can open table. Bring that strong.” up. Her unusual career has included “You think that people who are so teaching elementary school in Ghana, successful must have known from their working on solar energy in Australia and The future of science childhood, but in actuality they didn’t,” Canada’s north, and leading a NASA- said Serina Ykema-King, from Glenview sponsored mission in a “fake space” For the teens in the audience and Park Secondary School in Cambridge. dome in Hawaii. watching online, the discussions opened their eyes to the huge variety of STEM “It’s nice to hear, because you go It’s not the kind of pathway you could careers, and to the hard work it takes to through high school worrying about plot out from the start. Rather, it built succeed. what you want to be when you grow and grew because Lenio was open to up. It’s more about living in the moment both opportunity and uncertainty. Eema Kagoma, a Grade 12 student at and just trying your best today, because St. John’s College in Brantford, wants to tomorrow you’re going to find your “There’s not one right way to go through be an architect. Before the event, she path.” engineering,” she said. had assumed that following that career path would require setting aside her And as for those goals of being an favourite subject: chemistry. Now, she’s Seeing the potential astronaut? Like the students in the keen to pursue chemistry as an elective audience, Lenio is still dreaming big. at university. All of the speakers agreed on one major “There’s still a possibility. There’s going point: there is more to STEM than meets to be another call for astronauts in four “I’m interested in biomimicry in the eye. Sadly, though, most youth don’t years. Maybe…” architecture. I’m interested in all the really get to see that varied landscape. different sciences and how I could meld – Tenille Bonoguore them into what I’m studying,” she said. Mechanical engineer Martha Lenio didn’t know what an engineer did The sheer variety of STEM careers took when she enrolled in the program at FURTHER EXPLORATION Amanda DeGasperis by surprise. “You the University of Waterloo. She wanted can’t always judge the job by the title. to be an astronaut, and figured it’d be Watch all of the talks from “Inspiring Jobs that I thought were certain things handy to be able to fix the spaceship. Future Women in Science” were actually completely different. It was on Perimeter’s YouTube channel really interesting,” said the Grade 11 “When I was their age, I didn’t know Youtube.com/PIOutreach student at St. Elizabeth Catholic High what engineering was,” Lenio said after School in Vaughan. giving her keynote speech. “I think that’s still a problem. People don’t know what Linamar Corporation Many of the students were surprised engineering or science jobs look like, or was the Presenting – and relieved – to discover that it’s that if you do one thing at university, it is Sponsor of IFWIS 2018. okay to not yet know what they want to possible to do a lot of different jobs out study. Indeed, keeping an open mind of one degree.”

35 WHAT'S PHYSICS GOOD FOR? The incredible MRI

They are commonplace now – with more than 46 million scans a year performed in the US and Canada – but magnetic resonance imaging (MRI) scanners still seem halfway to magic. They can look inside bodies to show not just bones, as X-rays do, but soft tissues like the brain, muscles, and organs, without delivering Izzy was born Israel Isaac Rabi, and Rabi went on to study chemistry and harmful radiation. Using incredible rechristened Isidor when he enrolled in then physics, earning a PhD in 1926. computations that turn raw data into public school. His parents were Austrian He spent two years in Europe immersing moving images, MRI scans can show immigrants and Orthodox Jews, devout himself in the new and booming field of tiny details of a beating heart, or even and poor. They lived in Brooklyn, New quantum mechanics, working with such the shape of thought as blood moves to York. Young Rabi was imaginative and giants as Bohr, Pauli, and Heisenberg. the most active parts of the brain. bookish. He had already memorized all the books in his house and schoolroom Rabi was particularly struck by a Dozens of physicists, doctors, medical – mostly Biblical creation stories and new result called the Stern-Gerlach researchers, and engineers laid the Yiddish folktales – when he spotted a experiment. It was already known that foundations for MRI in science and built classmate carrying a volume he didn’t certain particles, such as electrons and technologies on top of them. There are recognize. Where had it come from? molecules, had magnetic moments: patents, egos, and at least five Nobel The public library. It was 1908, and like tiny bar magnets, they had north prizes. But at the very beginning of Rabi was 10. The world was about to and south poles. In the Stern-Gerlach the story, the incredible MRI owes its change. experiment, a beam of such particles is existence to a boy named Izzy and the passed through a strong . fact that astronomy begins with an “A.” In the tiny Carnegie You’d expect particles imitating tiny Library, Rabi started in bar magnets to spread out as they are the A’s and quickly read deflected through a magnetic field: ones all the children’s fiction. with their north pole pointing straight up The next shelf was non- to go up, ones with their poles pointing fiction organized by down to go down, and those with their topic, beginning with pole pointing various degrees of sideways an astronomy book to go various shades of sideways, hitting about Copernicus and the backboard in a smear. But they his model of the solar don’t. They move only up and down. To system. “That was what a physicist, that’s a startling result. It’s as determined my life more if, having discovered that particles can than anything else,” he act like clocks, you then discover that wrote decades later. they always tell you it’s 6:00 or 12:00. “Reading that little book. It was so beautiful, so Running the beam of particles through marvellous. So simple!” a second magnetic field produces even Robert Oppenheimer, Isidor Rabi, H. M. Mott-Smith, He gave his bar mitzvah stranger effects. It turns out that particles and at Lake Zurich, Switzerland speech on the physics of do have a magnetic moment, but it comes only in a limited set of magnitudes and Credit: AIP Emilio Segrè Visual Archives, Fermi Film Collection electric .

36 directions. It is quantized. It is quantum. Rabi joined research on particle beams.

Stern and his team had been using non- uniform magnetic fields to study subtle effects. Rabi came up with a different approach, using a uniform field and setting the beam at a glancing angle, so the atoms would be deflected like light through a prism. It was a cleaner experimental setup, easier to use, and more accurate. This would become Rabi’s signature: reinventing experiments to be clean and clever, seeking insights that brought him, he wrote, “nearer to .”

“You’re wrestling with a champ,” he would tell his physics students. “You’re trying to find out how God made the world, just like Jacob wrestling with the angel.” Isidor Rabi, with his molecular beam apparatus Credit: AIP Emilio Segrè Visual Archives, Physics Today Collection Rabi returned to New York and Person(s): Rabi, I. I. (Isidor Isaac), 1898-1988 established a molecular beam lab at Columbia University, mapping the new property of quantized magnetic 1937, he added something new to his the atomic nuclei would absorb this moment, also known as “spin.” He spent setup: not just a magnetic field, but a pulse and flip their spin. When their spin the 1930s improving his technique. In pulse of radio waves. He predicted that flipped back they would re-emit the pulse – a signal the experimenters could detect. What is more, different kinds of materials absorbed and re-emitted pulses at different frequencies. By detecting these different frequencies, scientists could distinguish between materials – even within solids.

It’s called nuclear magnetic resonance, or NMR, and it won Rabi the 1944 . It’s the grandmother of technologies such as the atomic clocks used in modern guidance systems, NMR spectroscopy for material science and oil and gas exploration, and – of course – MRI scans.

Despite a life spent wrestling with angels, Rabi was no saint: he didn’t believe women could be physicists and never took a female student; he was a great mentor but a terrible teacher.

At the end of his life, Rabi developed cancer and went for an MRI scan. The machine had a mirrored inner surface. “I saw myself in that machine...” he wrote. “I never thought my work would come to this.”

Rabi, apparently cooking hot dogs on a cyclotron – Erin Bow

Credit: Fritz Goro, courtesy AIP Emilio Segrè Visual Archives

37 38 PARTICLES

Perimeter continues Laflamme named Pedro Vieira Buchalters streak to Order of Canada wins Sackler Prize Perimeter Institute Director Neil Turok Perimeter researcher Pedro Vieira has and former Perimeter postdoc Steffen been awarded the prestigious Raymond Gielen won second prize in the annual and Beverly Sackler International Prize in Buchalter Cosmology Prize for their work Physics for his novel and powerful work probing the genesis of the universe. It in quantum field theory. Vieira, who is the fourth win in as many years for holds the Clay Riddell Paul Dirac Chair Perimeter researchers, whose work at Perimeter, was named co-winner of the has been honoured each year that the award for innovative work that has shed awards have existed. new light on the foundations of quantum field theory. He shares it with Zohar The award recognizes Turok and Gielen’s , a founding Komargodski, a Weizmann Institute of paper, “Perfect Quantum Cosmological Perimeter faculty member and long-time Science professor and Perimeter Visiting Bounce,” which grapples with an director of the Institute for Quantum Fellow. hypothesis called the “.” Computing at the University of Waterloo, Perimeter-affiliated researchers also took has been granted one of Canada’s The $100,000 award from Tel Aviv third prize: Associate Faculty member highest civilian honours. In December, he University recognizes researchers under Cliff Burgess and Associate PhD student was appointed to the Order of Canada the age of 40 who have made outstanding Peter Hayman shared it with three other for his “outstanding achievements as and fundamental contributions to their collaborators for their paper, “Magnon an administrator and researcher who fields. Previous winners of the physics Inflation: Slow Roll with Steep Potentials.” has advanced quantum science and prize include Juan Maldacena, Nima technology in Canada.” Laflamme Arkani-Hamed, and Sara Seager. First prize went to Lasha Berezhiani of the was among 125 new appointments to Max Planck Institute for Physics and Justin the Order of Canada announced by Khoury of the University of Pennsylvania Governor General Julie Payette. for their paper, “Theory of Dark Matter Superfluidity.”

Perimeter @ PPF Perimeter Institute Director Neil Turok delivered the keynote address for 1,000 attendees of the Public Policy Forum Testimonial Dinner and Awards in Toronto on April 12. “Canada’s welcoming, forward-looking society is a magnet for talent,” he told the audience of leaders in public service, business, and academia. Turok dedicated the speech to friend and collaborator Stephen Hawking, recalling something Hawking said when visiting Canada for a research term at Perimeter: “The importance of special places and special times, where magical progress can happen, cannot be overstated.”

39 NRC @ PI: A meeting of the minds

Scientists from Canada’s National Research Council recently met with physicists at Perimeter to explore mutual interests in theory and experiment Mingling with the Minister across a number of fields. The two- Canada’s Minister of Science, the Honourable Kirsty Duncan, caught up with day workshop fostered new connections Perimeter researchers during a March visit to the Institute. The Minister shared and identified opportunities for possible insights on new public investments in science and education, and met with a mix of training and research collaborations in Perimeter physicists to learn about their individual research activities. the future.

A Royal appointment WMAP team wins Connecting Canada at the AAAS It was the experiment that marked the end of the beginning. By mapping the radiation left over from the big bang – known as the cosmic microwave background – the Wilkinson Microwave Anisotropy Probe (WMAP) brought precision to cosmology and set the stage for a deeper understanding of the universe.

In December, the team behind that experiment won the 2018 Breakthrough Prize in Fundamental Physics, the richest prize in science. The $3 million prize was shared among the 27 team members, What is happening in Canadian AI including Perimeter Institute cosmologist research? That was one of the issues Kendrick Smith. up for discussion at this year’s annual meeting of the American Association Mathematical physicist Kevin Costello Perimeter Director Neil Turok said the has been elected a fellow in the for the Advancement of Science, held WMAP satellite provided invaluable in Austin, Texas. Perimeter Institute prestigious Royal Society of London, clues to the fundamental physics of the recognizing his pioneering research in Associate Faculty member Roger Melko . “We congratulate the whole joined CIFAR Vice President of Research quantum field theory. Costello joined the WMAP team, and our own Kendrick Perimeter faculty in 2013 as the Krembil John Hepburn and National Research Smith in particular, on winning this Council Vice President for Emerging William Rowan Hamilton Chair in wonderful prize. Kendrick played a Theoretical Physics, and before that was Technology Geneviève Tanguay to key role in analyzing the data of both discuss current and promising artificial at Northwestern University. “It’s a great satellites, and continues to pioneer data honour to join such a venerable scientific intelligence research taking place across analyses for CHIME, HIRAX, and other the country. society,” he said. leading-edge experiments.”

40 PARTICLES

In Memoriam McDonald Institute Power of Ideas tour launches comes back to Waterloo Perimeter Institute is among 13 partner organizations contributing to a new national hub of astroparticle physics at Queen’s University in Kingston, Ontario. The Arthur B. McDonald Canadian Astroparticle Physics Research Institute, launched in May, is a national research network dedicated to understanding some of the universe’s deepest mysteries. Perimeter Faculty Chair Luis Lehner said partnering with the McDonald Institute will facilitate “collaborative research in pursuit of answers to some of the deepest mysteries in science, and mutually We note with sadness the passing of strengthen the training and educational an old friend of Perimeter’s, Joseph outreach activities of both institutes.” Polchinski of UC Santa Barbara. An eminent theorist, he made fundamental Saucier + Perrotte contributions to our understanding of black holes and string theory. He was win RAIC Gold The popular Power of Ideas tour one of Perimeter’s earliest scientific The firm that created Perimeter Institute’s returned to Perimeter’s atrium in April supporters, and, as a member of the iconic building has been honoured for its for refurbishment before hitting the road legacy of inspiring architecture. Saucier again. The exhibit – which just finished a original Scientific Advisory Committee th from 2001 to 2004, gave extensive input + Perrotte founders Gilles Saucier and national tour during Canada’s 150 as into the structure and scientific direction André Perrotte were awarded the 2018 part of the Perimeter-led Innovation150 of the Institute in its earliest days. Gold Medal from the Royal Architectural collaboration – will now be taken Institute of Canada. “The work is across Ontario for two years. By visiting always innovative and interesting,” schools and communities across the Myers makes “most wrote the selection panel. “It’s timeless, province, Perimeter and its partners consistently elegant, beautifully detailed. aim to bring the magic of science and influential” list, again They integrate nature beautifully.” discovery to thousands more people. Visit powerofideas.ca to find out more.

Building quantum connections with the UK Sir Peter Knight and 19 other members of the UK Quantum Delegation travelled across Canada in March to connect with their counterparts in labs, accelerators, and funding agencies. Their visit to Perimeter included a lively conversation with Director Neil Turok on the Institute’s unique role for Canada and physics more globally.

For the fourth consecutive year, founding Perimeter Faculty member Robert Myers has been recognized as one of the world’s most influential scientists on the “2017 Highly Cited Researchers” list compiled by Clarivate Analytics. Myers is the only physicist at a Canadian institution to be named to the list four years in a row.

41 How are What does rainbows it look like inside made? a rainbow?

It’s hard to forget the breathtaking beauty example, from air to water), it changes of a rainbow once you’ve seen one. The direction slightly, or refracts. The amount splendid arcs of dazzling colour stretching of “bending” that occurs depends on across the sky have inspired countless the wavelength (or colour) of the light – myths, fairy tales, poems, and songs. At shorter wavelengths (corresponding to Perimeter, we think rainbows (and just bluer light) get bent more than longer about everything else in the universe) ones (redder light). only get more beautiful when we can understand what causes them. Next, it’s handy to know that white light isn’t actually light that doesn’t have colour. White light refracts (bends) when it enters a The recipe for a rainbow is surprisingly White (or clear) light is actually the result raindrop, reflects off the back of the drop, and simple: take some rain, add a bit of of blending all the colours of light, from then refracts once more when it exits. The angle between the light that enters and the light that sunshine, and mix at just the right angle. red to blue, together. exits is approximately 42 degrees. To put it all together, we need to use some of the rules that govern how light behaves. Now let’s mix in the rain. When a sunbeam, containing all colours of light, rainbows at noon, when the sun is high Let’s start with refraction. When light enters a round raindrop, the wavelengths in the sky: the sun has to be below 42 passes from one medium to another (for of light get refracted at different angles. degrees for the light to refract and reflect These refracted rays in the raindrops. The lower the sun is in then reflect off the back the sky, the higher the rainbow, so you’ll of the raindrop, and see the most spectacular ones at sunrise refract once more when and sunset. they leave the droplet. The end result is that the This angle also tells us why we white light from the sun get rainbows, and not rainlines or has been spread out, or rainsquares: if you map out all the points dispersed, into light of in the sky that are at just the right angle to different colours. With disperse the light, you get an arc! (Well, enough raindrops in the technically, you get a circle, but half of it sky, each one will disperse is blocked by the horizon.) a certain wavelength of light toward a viewer’s All of this also means that a rainbow eye. doesn’t exist in any one particular place, so you can never see inside it (or fly over Using optics, we know it, or under it, or get to the end of one). A that the angle between rainbow is essentially an optical illusion: the light that enters the there are no physical bands of colour It takes many raindrops to make a rainbow. Raindrops at droplet and the light that in the sky – just raindrops playing with different positions will refract different colours of light to your sunbeams! eye – that’s why a rainbow is red at the top and blue at the exits is about 42 degrees. bottom. (Note: image is not to scale.) This is why you don’t see – Stephanie Keating

42 Be part of the equation.

RESEARCH It’s a big universe. Fortunately, we have big ideas. EDUCATIONAL OUTREACH WOMEN IN THE NEXT Share the power, joy, and PHYSICS wonder of science. GENERATION Curiosity doesn’t Brilliant young people are have a gender. the lifeblood of science.

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Perimeter Institute (Canadian charitable registration number 88981 4323 RR0001) and Friends of Perimeter Institute Inc. (United States EIN 05-0553637) are charitable organizations devoted to fundamental physics research, training, and educational outreach. 43 44