History and

PhilosophyNEWSLETTER Physics

A FORUM OF THE AMERICAN PHYSICAL SOCIETY • VOLUME XIV • NO. 6 • SPRING 2021

US Airforce Support of General Relativity: Chapel Hill 1957 and Beyond[2]

By Joshua N. Goldberg (deceased), Syracuse University [1]

his memoir is a somewhat enlarged version of a talk theory, in particular Einstein’s theory of general relativity, given at the annual meeting of the APS in Columbus, and to grant support to individuals and institutions who Ohio on April 17, 2018. The session was devoted to were engaged in such research. The first thing I did was Tcelebrating the Chapel Hill Conference on The Role of to visit Peter Bergmann at Syracuse University and John Gravitation in Physics which was organized by Cecile and Wheeler at Princeton. The purpose was to let them know that Bryce DeWitt of the Institute of Field Physics. The conference support was available from this new office at ARL. At the took place at Chapel Hill from January 18–23, 1957. At the time, I had just arrived at the Aeronautical Research Labora- Continues on page 9 tories (ARL) at Wright Patterson Air Force Base to begin an in house program along with external support of research on gravitation—in particular, Einstein’s theory of gravity. I took the invitation to speak as an opportunity to describe the brief period of seventeen years that the Air Force supported In This Issue research in general relativity at ARL (Aerospace Research Laboratories after sputnik). US Airforce Support of General Relativity: I arrived at the ARL, in September, 1956. There I found Chapel Hill 1957 and Beyond 1 a group in solid state physics primarily engaged in growing CdS crystals and studying their electrical properties. Another group had a 4 Mev van de Graaf generator and was measur- The Indian contribution to the physics of ing nuclear energy levels. Although there were civilian physi- black holes: 2020 Nobel Prize” 2 cists engaged in the work, both groups were mainly staffed by graduates from ROTC programs who were assigned to ARL for a two year tour of duty. There were also PhD physi- Officers and Committees 2 cists so assigned. Two that I remember were Lee Pondrom, in particle physics, who went to the University of Wisconsin in Madison and Paul Derain, in solid state physics, who went to Brandeis University. In addition to the local research pro- In Memoriam: Joshua N. Goldberg 3 grams, they monitored research contracts at universities and other institutions. Separated from the physicists, there was a group of German mathematicians who were brought over Review of Proving Einstein Right 4 in Operation Paperclip. We were separated by a glass wall. We each knew the other was present, but we did not interact and I did not know what they were working on. FHPP News 5 Max Scherberg, a mathematician, was the Senior Scien- tist at ARL. It was he who decided that it was important to initiate support for general relativity at the Laboratory. I was hired through the recommendation of Peter Bergmann. As March 2021 FHP Sessions 6 noted earlier, my position was to do research in gravitational The Indian contribution to the physics of black holes: 2020 Nobel Prize [1]

By Naresh Dadhich, Jamia Millia Islania, New Delhi, India

‘If I have seen further than others, its own gravity ultimately ends up in Black holes two centuries ago it is by standing on the shoulders of singularity (Stephen Hawking had col- Giants’; thus spoke the great Newton laborated with Penrose in proving the The Indian connection to the term in 1675. If Newton needed the shoul- famous singularity theorems, and he ‘black hole’ is the infamous incident ders to stand on, so would everyone could have perhaps shared the Prize that dates back to 1756, when Nawab else. No discovery in science is made had he been alive), where its size goes Siraj-ud- Daulah squeezed 146 Brit- in vacuum, it is always anchored in to zero and energy density to infinity. ish soldiers into a dungeon, 14 18 sq the background which serves as a Not only that, on the way to singular- ft, overnight in Fort William—which conducive platform for creative and ity it would turn into a black hole. This was known as the Black Hole of Kol- imaginative minds to see further than is the robust prediction of Einstein’s kata. The message to be taken from others and make new discoveries. In theory of gravitation—general relativ- and which is relevant for visualizing this note I will discuss some seminal ity. The other half of the Prize is shared a physical black hole is that very large Indian works that could be taken as by two astronomers, American Andrea mass being confined to a very small ‘the shoulders’ on which Roger Pen- Ghez and German Reinhard Genzel for volume with diverging density. rose might have been riding on to see detecting independently a supermas- It is interesting that the first concep- further and deeper into a collapsing sive star, believed to be a black hole, tion of the black hole as a scientific pos- star turning into a black hole. at the centre of our galaxy, the Milky sibility was to follow pretty soon after The 2020 Nobel prize in physics Way. It should be noted that it is this by the British clergyman and scientist has been awarded to Penrose[2] for remarkable observation that has lent John Michell in 1784 and the great proving the powerful mathematical the observational verification of the theorems that established rigorously Hawking and Penrose prediction—a that a massive star collapsing under critical requirement for a Nobel Prize. Continues on page 11

HistoryNEWSLETTER and Philosophy Physics Forum on History and Philosophy of Physics | American Physical Society, One Physics Ellipse, College Park, MD 20740

Forum Officers Program Committee Chair: Michel H P Janssen Chair: Paul Halpern The Forum on History and Philosophy Vice Chair: Alberto A Martinez Melinda Baldwin of Physics of the American Physical Chair-Elect: Paul H. Halpern Jinyan Liu Society publishes this Newsletter Past Chair: Joseph D Martin Alberto Martinez biannually at http://www.aps.org/units/ Secretary-Treasurer: Tiffany Nichols fhp/newsletters/index.cfm. Each 3-year Dwight E Neuenschwander volume consists of six issues. Nominating Committee Forum Councilor Chair: Joseph Martin The articles in this issue represent the Virginia Trimble TBA views of their authors and are not necessarily those of the Forum or APS. Other Executive Board Members Fellowship Committee Melinda Baldwin Chair Alberto Martinez Jinyan Liu TBA Editor Jami Valentine Miller Donald Salisbury Tiffany Nichols Pais Prize Committee Department of Physics Chanda Prescod-Weinstein Chair: Dieter Hoffman Austin College Rudolf M Tromp Melinda Baldwin Sherman, TX 75090 Hasok Chang Gregory Good (AIP) [email protected] Jinyan Liu Donald Salisbury (newsletter) (214) 405-6188 Gregory Good (ex-officio)

2 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter In Memoriam: Joshua N. Goldberg

By Donald Salisbury, Austin College

oshua N. Goldberg was one of the leading general relativists of the twentieth century. He made major Jcontributions in the development of the theory describing the generation and propagation of gravitational waves, and in his capacity as an administrator of US Air Force funding he was largely responsible for the financial support of research in general relativity in the late 1950’s and early 1960’s, a period now recognized as a Renaissance era of gen- eral relativity. The Goldberg name had been assigned to his Russian emigrant father at Ellis Island. The original Jew- ish name was Sclaroff[1]. Josh was born in Chicago on May 30, 1925. He passed away on October 5, 2020. I was privileged to have known Josh both as a teacher and a friend, begin- ning when I entered the graduate phys- ics program at Syracuse University in the Fall of 1968. I will include here some of my personal reminiscences, supple- mented with a series of interviews that Art Komar, Peter Bergmann, and Joshua Goldberg at the 1962 Warsaw I recorded with him over the years. A relativity meeting. Paul Dirac in the foreground. broader overview of his work can be (Photo courtesy of Joanna Robinson) found in an upcoming book[2]. I still recall the gracious invitation to visit his contribution to general covariance. Josh to him the issue of strong conservation, home that he and his wife Gloria made exploited the fact that general covari- which he probably knew, but had never to us incoming graduate students that ance leads to a strongly conserved expressed it. But nonetheless, I thought Fall. Josh had returned to Syracuse in pseudo stress-energy tensor. Strong I was telling him something new. I’ve 1963, having left after obtaining his PhD conservation means that its divergence always afterward been a little embar- in relativity under the direction of Peter vanishes whether the field equations rassed by that thought. But, so it goes. G. Bergmann in 1952. He was in fact one are satisfied or not. It follows that this Anyway, he did seem interested. But of Peter’s first students. I was fortunate pseudo tensor can in turn be written as he was not really interested in equa- to have been introduced to relativity in an antisymmetric superpotential, and tions of motion. If I come to him and a two semester graduate course taught this antisymmetry was precisely what show him a plane wave solution, any by Josh in the academic year 1972–73. he had sought to find. wave solution, he would have been It played a major role in my decision to In 1952 he went to work at the ecstatic, but he was not interested in complete my thesis in this field under Armour Research Foundation in Chi- radiation from moving particles.”[4] Bergmann’s supervision. cago. He was able to find time while At ARL he worked in 1962 with Peter The central focus of Josh’s thesis working on applied physics problems Havas on a `fast motion` approxima- was the explicit demonstration of the to continue with his thesis focus. Much tion, with a pioneering treatment of link between the general covariance came to fruition after securing his Green function divergences. This same of general relativity and the iterative position at the Aerospace Research year he obtained a leave to work as a approximation procedure that had Laboratories (ARL) in 1954. Major National Science Foundation Fellow been introduced by Einstein, Infeld, innovations included a focus on the at the University of London. There he and Hoffmann to deduce particle equa- role of the Riemann tensor in identify- joined forces with another former Berg- tions of motion. The EIH procedure was ing gravitational radiation and a correct mann student, Ray Sachs, to achieve his based on what they called ‘the lemma’, tracking of coordinate conditions in v/c likely best known theoretical result, the a consequence of the fact that the field expansions in work on source equations Goldberg-Sachs theorem[5]. Prior to 1962 equations contained an anti-symmetric of motion[3]. 1954 was the year in which contribution. Bergmann made the first he had the opportunity to discuss his step in 1949 in tracing the origin of this work with Einstein. “And I explained Continues on page 15

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 3 Review of Proving Einstein Right

Reviewed by Dwight E. Neuenschwander

Proving Einstein Right: best-laid plans could be obliterated 1912 eclipse was the first attempt to The Daring Expeditions that Changed in seconds by rain or clouds. The explicitly test Einstein’s light deflection How We Look at the Universe outbreak of regional or national prediction. by Sylvester James Gates, Jr. and conflict could entirely undo a well- On these expeditions we board Cathi Pelletier planned expedition. Gone from their ships for two-week voyages and climb families for months at time to for- aboard railroad cars for 13-hour train (Public Affairs, New York, 2019), eign lands and unforgiving climates, rides. Upon our arrival we are met by illustrated, 325 pages these astronomers faced illness and local dignitaries, welcomed as VIPs possible death from bubonic plague, and made the talk of the town. We help Every physics major knows that the malaria, yellow fever, and the Span- choose the local observing site, renting 1919 British solar eclipse expeditions ish flu. They protected themselves a patch of someone’s estate or the local supported Albert Einstein’s prediction as best they could from wild ani- jockey club. We help manhandle equip- of starlight deflection by the Sun. But mals, poisonous stakes, venomous ment from the train station to the view- the backstories behind great discover- insects, floods, forest fires, food ing site, then build sturdy platforms ies are seldom told in textbooks; little poisoning, and local superstitions. for telescopes and cameras. That done, beyond essential headline facts are well But through it all, their mission we tag along on sightseeing excursions known. remained clear…”(3) to tropical jungles, mountain vistas, art History told through the inti- museums, and quaint towns, all the mate personal experiences of others While becoming closely acquainted while anxiously watching the cloud pat- acquires an immediacy that can only with the principal actors and their terns, fervently hoping for clear skies be improved by having been there our- families, the reader is witness to and during the upcoming big day’s few selves. Anne Frank’s diary, and Charles becomes a participant in the travel minutes of totality. Darwin’s diary from the Beagle’s expe- hassles, insects, torrential rains, local “If you read only scientific papers dition, illustrate the point. superstitions, and other joys of solar in academic journals, you would think By sifting through letters, articles, eclipse expeditions from before 1900 that these Victorian astronomers were and other primary source accounts, through 1919. The wealth of details in concerned only with hard work. But Sylvester James Gates, Jr. and Cathie Proving Einstein Right, especially details private letters and accounts sometimes Pelletier have written such a compre- not essential to the ultimate outcome, suggest otherwise.”(40) Work hard hensive “diary” for the personalities make visualizable in living color the they did—but we also see a case of fine and events of the solar eclipse expedi- motivations and logistics of those ambi- wine being smuggled out of Portugal tions that culminated in the great 1919 tious expeditions in a bygone era. following the 1900 eclipse, the bottles result. “Over the course of a decade” During the solar eclipses of the early deftly packed in instrument crates. they write, “several esteemed astrono- 1900s the research priorities were solar The inquiring customs officer is cooly mers in four countries would take on corona studies and searches for the informed that the crate in question the ‘Einstein problem’ in what would hypothetical planet Vulcan that was contains “a special instrument used become an epic tale of frustration, faith, supposed to account for the anomalous to study double stars.”(40) Enroute to and ultimate victory.”(p. 4) The book precession of Mercury’s orbit. When Príncipe aboard the small steamer Por- takes us through the epic tale in colorful Einstein made his preliminary calcula- tugal, Arthur Eddington lacks sufficient detail, enabling the reader to be there. tion of starlight deflection, he “needed room for his daily workout, so he and Doing astronomy today by sitting two things: a total believer, and a total Edwin Cottingham “took part in impro- before a computer screen linked to eclipse of the sun.”(31) He got the first vised games that were played by the a distant telescope is another world by seeking advice from colleagues at passengers. It’s comical to imagine the compared to Victorian-era astronomy. the University of Prague who contacted Plumian Professor of Astronomy and We have greater security, but they had the Berlin Observatory, producing a the director of the Cambridge Observa- more adventure. Gates’ and Pelletier’s response from Erwin Finlay-Freundlich, tory engaged in Boots without Shoes, offer this preview: a former student of Felix Klein and Karl Rings without Strings, egg-and-spoon Schwarzschild. Freundlich was the first races, and Threading the Needle.”(179) “From the mid-1800s into the first astronomer to show “spirited interest” For the 1912 eclipse in France, help- two decades of the 1900s, [astrono- in the light deflection prediction of ful amateur John Atkinson ships his mers]… planned for months and general relativity.(34) He was advised to Gobron-Brillié roadster across the Chan- even years before journeying to contact Charles Perrine of Lick Obser- nel so he and Sir Frank Dyson can tour exotic parts of the world. Travel vatory about existing photographs. the countryside afterwards. “They by boat, train, wagons, and pack Having recently been made Director animals was always rigorous and of the Argentina National Observatory, often dangerous. And yet, their Perrine’s Brazilian expedition for the Continues on page 18

4 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter FHPP News

Change of Forum name and science from Australia, Brazil, Canada, organize workshops in which a diverse modification of by-laws China, Denmark, France, Israel, Japan, cohort of physicists will receive training Mexico, Spain, and Sweden. There are in communication from media profes- The FHP membership voted at the currently five project subgroups: sionals and to create networks that can start of the year 2021 to change the connect scientists, outreach profession- name of the Forum to The Forum on 1. Women in Quantum Physics. One als, and those in media interested in the History and Philosophy of Phys- immediate goal is to organize promoting quantum understanding ics (FHPP). Some changes in the unit invited sessions at the March and and enthusiasm. To this end Group by-laws were also ratified. They are April 2022 APS meetings with members Spyridon Michalakis, Man- available here: https://engage.aps.org/ FHPP sponsorship. ager of Outreach for the Institute for fhpp/governance/bylaws 2. Genealogy of quantum textbooks. Quantum Information and Matter at The initial focus is on tracking Cal Tech, and former FHPP Chair Paul English language texts, but the Cadden-Zimansky partnered with the The Quantum Century Project intention is to branch out to oth- National Academy of Science’s Science and World Quantum Day er languages and regions. The & Entertainment Exchange for a World group is preparing a question- Quantum Day event where Hollywood The Quantum Century Project, naire asking physicists from which screenwriter Kieran Fitzgerald inter- which aims to mark the centennial of textbooks they learned quantum viewed physicist Carlo Rovelli in front the birth of quantum mechanics in 2025 mechanics as students and which of a virtual audience of over 600 people. with a global celebration and public books they have been using to outreach campaign, has continued to teach their own students. develop along multiple fronts. The 3. Archives. Various archives around “Quantum Century” Project Project, initiated by the FHPP and other the world are directly represented. in China Forums and subsequently taken up by Copyrights will be sought, and the APS as a whole, has a growing cadre an effort will be made to make By Jinyan Liu, Institute for the History of of working groups and international archival resources available to a Natural Science, Beijing, China partners focusing on different topics wider public. For the April 14th World Quan- and geographical regions. A particu- 4. History of understanding of quan- tum Day the launching ceremony of larly useful partnership has been with tum mechanics. Olival Freire of the “Quantum Century” Project in China members of the European Commis- Universidade Federal da Bahia is was held under the organization of the sion’s Quantum Flagship initiative who the chair. An effort will be under- International Centre for Theoretical have spearheaded an inaugural World taken that transcends traditional Physics Asia-Pacific (ICTP-AP), Insti- Quantum Day that was announced on disciplinary boundaries. tute of Theoretical Physics, Chinese April 14 of this year. Serving both as 5. Institutional Geography and Indi- Academy of Sciences (ITP-CAS) and an annual occasion to build up to and vidual Trajectories. The Chair the Institute for the History of Natural to echo the year-long 2025 events, this is Kristian Camilleri from the Sciences, Chinese Academy of Sciences Day has also already allowed a useful School of Historical and Philo- (IHNS-CAS). This meeting attracted an platform for testing different modes of sophical Studies of the Univer- audience of nearly three thousand both quantum outreach. sity of Melbourne, Australia. The on-site and online. Summaries from several sectors are above topics will be tracked on a Prof. Yueliang Wu, academician of below. Those FHPP members interested website map. the CAS, academic vice president of in helping to contribute to the early the University of CAS, director of the stage planning of the Project should ICTP-AP, gave a lecture on “Embrac- contact Quantum Century Working U.S./Canada Outreach ing the New Quantum Century and Group Chair, and former FHPP Chair, Working Group Igniting a New Scientific Revolution”. Paul Cadden-Zimansky He reviewed the important achieve- The quantum century U.S/Canada ments in the development of quan- Outreach Group is responsible for tum theory in the past 100 years, and History Working Group developing the communication and emphasized the background and The History Working Group is co- outreach infrastructure of the project in mentorship of scientists such as M. chaired by Alexander Blum from the these regions. The current focus is on Planck, N. Bohr, M. Born, W. Heisen- Max Planck Institute for the History developing a webpage branding and berg and E. Schrödinger when they of Science in Berlin and current FHPP design strategy. In this effort the group Chair Michel Janssen of the University is assisted by GitHub Design Director of Minnesota. It includes historians of Sam Oshin. One aim of the group is to Continues on page 19

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 5 March Session Report: “Farm Hall Revisited”

By Mark Walker

t the March 15th, 2021 meeting of the American Physical Soci- ety, a history of physics panel Awas held on “Farm Hall Revisited.” This session was inspired by the award of the 2020 Abraham Pais Prize for History of Physics to Dieter Hoffmann “for insightful, determined, often cou- rageous biographical and institutional studies of the history of German physics and technology, from Weimar through the Nazi and East German regimes.” Dieter requested that, instead of him giving a talk, he participate in a panel discussion of an important topic of interest to a wide audience. The subject chosen was “Farm Hall”: after the Sec- ond World war, ten German scientists, most of whom had worked on the Ger- man wartime uranium project, were interned in an English country house called “Farm Hall,” where their conver- sations were overheard and recorded, including their reactions to the news of Hiroshima. Since the April, 2020 APS meeting was cancelled due to the COVID pandemic, the session, which A diagram used by Werner Heisenberg in a February, 1942 lecture. Mark Walker, was chaired by Michel Janssen from the German National Socialism and the Quest for Nuclear Power, 1939-1949 School of Physics and Astronomy at the (Cambridge: Cambridge University Press, 1989), 56. University of Minnesota, was included this year. The first talk was given by David Cassidy, Professor emeritus at Hofstra he turned the drama of Farm Hall into a rare primary document that quite University and the author of the defini- a play, exploring the captured German literally reproduces real-time conversa- tive biography of Werner Heisenberg, scientists’ struggles with their past, tions, one might expect the Farm Hall a book on J. Robert Oppenheimer, their reaction to Hiroshima, and their transcripts to be the definitive source and other publications. Most recently concern about their uncertain futures on wartime German nuclear intentions. David has become a playwright and in order to open new perspectives on a Yet since 1945, these recordings have published the play: Farm Hall and the crucial turning point in physics. How- been used to make radically different German Atomic Project of World War II: A ever, the talk went beyond Farm Hall to arguments about the abortive program. Dramatic History (Cham: Springer, 2017). a discussion of playwriting in general, Allied scientists like Samuel Goudsmit This drama highlights several incidents especially drama designed to educate used them in an attempt to prove that that bring the story to life, including the audience about science as well. Heisenberg and the Germans got their the Germans’ confused response to Ryan Dahn completed his Ph.D. in physics wrong when trying to construct the news of the atomic bomb and the 2019 at the University of Chicago on a bomb—but that the Germans would surprise announcement of Otto Hahn’s “The Forgotten Founder of Quantum have willingly provided Hitler with a Nobel Prize. Farm Hall thereby comes Mechanics: The Science and Politics of nuke if only they could. Others, like alive, with all the important contradic- Physicist Pascual Jordan, 1902–1980,” the journalist Thomas Powers, have tions and conflicts it embodies. His and held a postdoctoral position at the used them to spin a fanciful narrative book should be of special interest to Consortium for the History of Science, of scientific resistance inside the Nazi physicists and physics students and is a Technology, and Medicine in Phila- regime. The former internees them- valuable addition to our understanding delphia, and is now the Books Editor selves, particularly Heisenberg and von of this ambiguous chapter in the history at Physics Today. Dahn spoke on “The of modern physics. David’s talk, “The Use and Abuse of Nuclear History: Drama of Farm Hall,” described how Farm Hall in Historical Memory.” As Continues on page 14

6 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter March Session Report: “The Author in Dialogue: Jeffrey Bub’s Bananaworld”

By Michael Cuffaro

his session, dedicated to the book Bananaworld: Quantum Mechanics for Primates and to Tthe information-theoretic interpreta- tion of quantum mechanics defended within it, had talks by four speakers: Leah Henderson (University of Gron- ingen), Michael Janas (University of Minnesota), Michael Cuffaro (LMU Munich), and Jeffrey Bub (University of Maryland). The titles of the talks were: Pragmatism: a natural home for information-theoretic interpretations of quantum theory? (Henderson), Elliptopes and polyhedra: quantum correlations and their classical simulations (Janas), Inter- preting quantum mechanics (Cuffaro), Leah Henderson screenshot and Bananaworld: quantum mechanics for primates (Bub). The session was chaired by Michel Janssen (University of Min- American Pragmatism might function In the second talk of the session, nesota). It had 62 unique viewers, as a suitable philosophical foundation. Michael Janas presented a number of and as of March 17, 16 unique further Pragmatists are realists but resist the results regarding elliptopes, polyhe- viewers have watched it on demand ideal of the “detached observer” and dra, quantum correlations and their (source: Hunter Clemens, APS director emphasize the centrality of the agent, classical simulations. He began by of meetings). clarifying meaning by tracing out the introducing an analogy between spin Henderson began the session by practical consequences of action. Hen- measurements and “peeling and tasting discussing the roots of the information- derson suggested using American bananas”, a pedagogical device used theoretic interpretation in the ideas Pragmatism’s alternative understand- both in Bananaworld and in the take on defended by the circle of thinkers asso- ing of realism as a rhetorical counter to the information-theoretic interpreta- ciated with Niels Bohr and Werner some of the criticisms of information- tion, inspired by Bananaworld, laid Heisenberg, on the one hand, and theoretic interpretations that equate it out in the book by Janas, Cuffaro and in contemporary re-axiomatization with instrumentalism. In the question Janssen: Understanding Quantum Raffles: programs, on the other. She then dis- period, Bub commented that part of the Quantum Mechanics on an Information- cussed what the core commitments of point of the information-theoretic inter- Theoretic Approach: Structure and Inter- an information-theoretic interpretation pretation is that quantum mechanics (if pretation. In Understanding Quantum of quantum mechanics are: That the we take it seriously) limits the ways that Raffles, bananas are identified with quantum state is a book-keeping device we can conceive of reality, effectively spin-1/2 particles, peelings with mea- for keeping track of probabilities, that ruling out (via its non-Boolean algebra surements of components of their spin, there are objective constraints on these of observables) the detached-observer and tastes with the outcomes of such probabilities, that the projection postu- conception. Bub noted that associating measurements. Janas then introduced late is a quantum version of the classical the view too closely with a particular the experimental “Mermin-setup” Bayesian updating rule, and that the philosophical position from the outset (inspired by an example of N. David measurement problem is thereby dis- may obscure this point. In response, Mermin’s) used in Understanding Quan- solved, with the realization of a particu- Henderson clarified that appealing to tum Raffles, its associated correlation lar measurement outcome understood pragmatism should not be thought of as array, and the correlation coefficients as a truly random event. Henderson a justification for the view but instead as that can be used to parameterize such considered the question of whether a rhetorical counter to those who accuse arrays. He then introduced the concept information-theoretic interpretations the information-theoretic interpretation of a “raffle”, i.e., a toy model, with local are realist, and she discussed some of instrumentalism. The point of this hidden-variables modelled as raffle ways to make sense of the ontological rhetorical counter is that the detached- tickets, to reproduce the correlations commitments of information-theoretic observer conception of reality is not the interpretations. She asked, in particular, only possible option and that there are whether the philosophical view called alternatives. Continues on page 16

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 7 March Session Report: Pais Prize

By Hasok Chang

was extremely honored and pleased such a learning process, the quality to deliver the Abraham Pais Prize of our knowledge is enhanced. It is Lecture at the APS March Meeting also helpful to look at the history with I(online) on 18 March 2021. There have full respect for the past scientists, and been a great number of highly respected recognize that the scientific common historians of physics in our time, and sense of today was once the subject of there is injustice in my receiving the controversy and exciting cutting-edge Pais Prize before many of them. But I research. Going back to early periods of believe that my work is at least distinc- science with this kind of historical per- tive and unusual, and in the lecture I spective can also help us regain a sense tried to convey the spirit and purpose of fascination in the familiar aspects of of my research. nature. Making the science of everyday My historical work is strongly and phenomena come alive can help us explicitly motivated by philosophical instill a love of science in students and concerns, focused on the question of the general public. how we know what we know. And I like Another key feature of my historical to dig into the justification of the most work is giving attention to past scientif- basic items of scientific knowledge that ic knowledge that scientists themselves we all take for granted and rely on. My tend to disregard as misguided or not Hasok Chang first two books were on the question of worth remembering. In the discarded how physicists and chemists learned past of science we can often find some- to make thermometers (Inventing Tem- thing valuable. The history of science Gay-Lussac reported in 1812 that water perature, 2004), and how they learned presented in science textbooks tends boiled at exactly 100°C in a metallic the basic atomic–molecular composi- to be a picture of past heroes who vessel, but at around 101.2°C in a glass tion of matter (Is Water H2O?, 2012). anticipated modern knowledge, such as vessel. Biot repeated this claim in his For example, it took chemists about Galileo, Newton, Maxwell and Einstein. textbook of physics. half a century to agree on the H2O for- That has its purpose, but as a profes- I had to check this out. And I was mula for water, starting with Dalton’s sional historian I make it my job to pay easily able to confirm Gay-Lussac’s view that it must be HO since that was more attention to the “losers” of past result, in about 20 minutes. But such the simplest possibility. Avogadro’s science. Through such historical work a thing was never mentioned in all original proposal of the H2O formula we can recover forgotten ideas and phe- the physics I studied at Caltech as an was sensibly inspired by the observed nomena. A further examination of such undergraduate! Later I learned that 2:1 gas-volume ratio in the combina- recovered knowledge can even lead to there are boiling experts in engineering tion of hydrogen and oxygen gases, new scientific knowledge. departments who know all about such but making the whole story coherent A memorable case of such recovery things, but it is not general knowledge required Avogadro’s hypothesis (equal of neglected knowledge occurred in among physicists and chemists. Return- number of molecules in equal volumes the course of my work on the history ing to the history: Gay-Lussac was in of all gases), and the assumption that of temperature and thermometers. I fact reporting nothing new. For exam- hydrogen and oxygen gases consisted was asking myself how people knew ple, De Luc had made elaborate investi- in diatomic molecules H2 and O2. These how to make thermometers, without gations on the boiling of water 40 years assumptions were rejected as ad hoc and having the kind of knowledge of ther- earlier. One key discovery he made was physically unfounded. (Why would mal physics that they could have only that the amount of dissolved gases was two oxygen or hydrogen atoms stick got by already having thermometers a crucial variable in determining the together, and if two of them will, why they could trust. For example, how boiling temperature and behavior of not more?) The eventual agreement on did they know that the “fixed points” water. He made highly de-gassed water, molecular formulas came only around of thermometers were actually fixed which did not bubble up at all until 1860, through the establishment of the in temperature? I quickly learned that it reached 112°C, and then exploded. idea of valency after a great deal of there had actually been plenty of doubts Less dramatically, boiling water in a work in organic chemistry. and disputes about the various pro- thin-necked flask with slow heating Through learning this kind of his- posed fixed points, the most famous of produces very interesting results; the tory we learn why we have come to which was the boiling point of water. process of boiling itself promotes de- believe what we now take as basic I read many reports of strange and gassing, and the small surface area truths in science, and what the points hard-to-believe variations in the boiling of contention were along the way. temperature of pure (distilled) water With the critical awareness gained in under standard pressure. For example, Continues on page 19

8 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter US Airforce Support of General Relativity: Chapel Hill 1957 and Beyond

Continued from page 1 time, I was unaware of the formation Tommy Gold discussed cosmological particularly grateful to Cecile and Bryce of the Institute Of Field Physics (IOFP) models, presented issues of measure- for organizing this meeting. by Cecile and Bryce DeWitt at the Uni- ment, and Robert Dicke discussed the The end of the Chapel Hill Confer- versity of North Carolina at Chapel Hill. observational data. The Air Force con- ence did not end US Air Force support However, I soon became aware of tract for the meeting required a report. of the subsequent meetings. Military Air the IOFP, when I received call from That report could have been quite brief. Transport System support was available Bryce DeWitt to discuss his and Cecile’s However, Cecile and Bryce wanted a for US scientists to attend the meetings interest in organizing a conference on detailed description of the proceed- in France, Poland, and Britain. Travel general relativity in January of 1957 to ings. There were recordings of the talks to Poland was supported only as far be held at Chapel Hill under the spon- and discussions and individuals were as Paris, France, but not to Warsaw, sorship of the Institute. I assured him of requested to submit their comments Poland. In 1968, the Air Force refused Air Force support and requested a for- as well. The result was the publication to grant support for the GRG meeting mal proposal. The proposal came quick- by the Air Force of the report Confer- in the Soviet Union and there was no ly with a request for $5000 in support ence on the Role of Gravitation in Physics further travel support for meetings of the conference. After a quick review, which was rather widely distributed. through ARL as far as I know. the Air Force wrote a contract with Cecile DeWitt and Dean Rickles have For the next year and a half, I mostly the University of North Carolina for a produced a reprint[2] with an historical worked alone on research as well as conference on general relativity to be preface and an additional remark by monitoring contracts. In the course of held under the auspices of the Institute Feynman as an end paper. time, the Air Force supported Peter of Field Physics. In the course of a con- This was not the end, however. As Bergmann at Syracuse, Hermann Bondi versation, Peter Bergmann suggested the conference was coming to an end, at King’s College London, Ted Newman that the Air Force be asked to transport at the urging of the younger people, the and Allen Janis at Pittsburgh, Nathan people from abroad. I received Air Force senior participants, Peter Bergmann, Rosen at the Technion in Israel, Pas- support for the request and asked Bryce John Wheeler, Hermann Bondi, and cual Jordan in Hamburg, Oscar Klein in for names of those invited. In my mem- André Lichnerowicz had an informal Stockholm, Peter Havas at Temple, and ory, the travel request listed Hermann discussion and decided that in the sum- many others. Bondi and Felix Pirani from Britain; mer of 1959 there would be a follow In the summer of 1957, I was able to André Lichnerowicz, Yvonne Choquet- up meeting in France and subsequent arrange a two month appointment for Bruhat, and Mme Marie Anntoinette meetings in three year intervals. In time, Ted Newman who had just completed Tonnelat, from France; Nathan Rosen a formal organization was formed, the a year at the University of Pittsburgh. from Israel; and Jules Geheniau from International Committee on General During this time we worked on the Belgium. Ryoyu Utiyama from Japan Relativity and Gravitation (ICGRG). measurement of distance in cosmology. and Behram Kursunoglu from Turkey Roberto Lalli has written a detailed his- For this, we used the geodesic deviation were also present, but I don’t remem- tory of its formation and its transition to of light. I attribute this work to Ted’s ber whether they were among those the ICGRG of today[3] continuing interest in the properties and transported. The Air Force approved As we were leaving, Joe Weber told applications of null rays. transportation for all except Geheniau me that he was working on gravitation- The following year, 1958, I went to who was considered too far to the left to al radiation, but did not say that he was Europe to visit the Air Force office in be brought to the United States by the planning to detect gravitational waves. Brussels and was able to visit with Jules Military Air Transport System. Except Two years earlier, in 1955, there Geheniau as well as Pascual Jordan in for Rosen, who did not come for per- was a meeting in Berne, Switzerland Hamburg and Andre Lichnerowicz in sonal reasons, the others did arrive and to celebrate the 50th anniversary of the Paris. I apologized to Geheniau for not did participate in the conference. 1905 publication of Einstein’s paper being able to bring him to the Chapel Hill The conference took place from introducing special relativity. Most Conference. He was very gracious, he January 18–23, 1957. Classical and quan- of us in the new crop of physicists gave me a copy of the report of the Berne tum relativity as well as cosmological interested in general relativity were conference, and invited me to come to models were discussed and argued. The not even informed that the meeting in a three day meeting in Brussels prior to issue of gravitational waves (talks by Berne was taking place and so did not the Royaumont meeting in 1959. Ted and Bondi and Pirani among others) took up attend although Stan Deser was there I were able to present our work on the much discussion with some remaining with Oscar Klein and Felix Pirani with measurement of distance at this meeting. skepticism. Andre Lichnerowicz and Hermann Bondi. As a result, the meet- The Air Force also allowed me to Yvonne Choquet-Bruhat spoke on the ing in Chapel Hill was the first time attend a workshop on quantum gravity initial value problem. There were long we younger colleagues had a chance in Neuchatel, Switzerland. The princi- presentations by Peter Bergmann and to get together with the established pal discussants were Richard Arnowitt, Bryce DeWitt on the issues and meth- physicists and mathematicians who had Stanley Deser, and Charles Misner with ods of quantizing the Einstein theory. published work in the field. We were their then idiosyncratic approach and

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 9 Bergmann and Komar with what one for Synge who had not followed that “It was Camelot as far as research atmo- could call a more conventional approach development. sphere went…My only non-research duty to quantum gravity. No middle ground In the fall of ’62, Roy left for a year was to monitor a few external grants and was found, but field theorists preferred with Alfred Schild in Austin. During to evaluate occasional proposals, most of ADM to BK. Wolfgang Pauli, who was that year, he wrote his paper on the which were for things like perpetual motion present for a couple of days, spoke rotating mass (rotating black hole). He machines. Money for travel and postdocs briefly and suggested that the attempts listed both the University of Texas and was abundant.” Beginning in 1966, Rich- at quantization were not crazy enough. ARL as his home. At some time in the ard Isaacson, David Robinson, Ed Glass, Perhaps that is still true. following year, I suggested that ARL Lou Derry, Mike Russo, and others In the summer of 1958, while I was develop a program with temporary whose names I don’t have were post- away, Max Scherberg had taken the post-doctoral positions. This was dis- docs for two year periods. privilege of hiring a student of Vaclav cussed in conjunction with other labora- At the end of two years, Isaacson H’lavaty, Joseph Schell, who had just tories at Wright Paterson Air Force Base went to IIT in Chicago and then to received his PhD. The Petrov classifica- and then went up the chain of com- NSF as Director of the Gravity pro- tion of the conformal tensor was still mand and was approved. The National gram where he vigorously supported relatively new. Joe made a classification Academy of Science was to select the the LIGO program. Robinson went using the infinitesimal holonomy group candidates who applied. However, that to King’s College London where he that is a refinement of the Petrov clas- program did not get under way until worked with Pirani – Bondi having left sification. This has not found much use after I left for Syracuse and Roy left for for the European Space Agency. Glass as it is much too refined and therefore Austin, Texas. Recently, I wrote to the went to Windsor University in Canada not easily applicable. In this time, Roy NAS to inquire whether the program and for 25 years was an Associate Edi- Kerr joined me and we found solutions still exists and received the following tor of the Canadian Journal of Physics. using the end of the classification which reply from H. Ray Gamble, PhD, Direc- I have not been able to find references is similar to the null case of the Petrov tor, Fellowships Office: to Derry and Russo. classification. ARL did support another Confer- In the fall of 1960, the Air Force “The AFRL postdoctoral program, as ence on General Relativity. It was orga- granted me a 16 month leave so I could administered by the NAS, began in nized by Louis Witten at the University go to King’s College on an NSF Senior 1965, with the first Research Associ- of Cincinnati and Stuart Fickler and Post Doctoral Fellowship and could ate beginning their tenure in March Moshe Carmeli from ARL. It took place visit various institutions and summer of 1966. Since then, we have awarded at the University of Cincinnati in July, schools during the summer months. a total of 1212 fellowships at AFRL 1969. The two things I remember about At King’s, I worked with Ray Sachs to locations. This program has oper- that conference were the incredibly prove that algebraically special space- ated under the umbrella of the NRC beautiful lectures by Bob Geroch on sin- times contain shear-free geodesic null Research Associateship Programs, gularities in the gravitational field and congruences. I also constructed con- which are funded, currently, by 23 the surprising lecture by Joe Weber in servation laws based on the identities federal sponsors and fund over 500 which he announced the observation of of the Riemann tensor using proper- Research Associates each year. Among Gravitational Radiation which was fore- ties of the asymptotically flat space- these, about 80 are at AFRL locations. shadowed by his comment to me at the time. During the summer, I was able More recently, AFRL has requested end of the Chapel Hill Conference. Joe’s to visit Lichnerowicz in Paris and Jor- we rename the program to the AFRL announcement opened up a scramble to dan’s group in Hamburg. In addition, Science and Technology Fellowship verify his results and ultimately led to I attended a summer school at Lake Program, although we still operate LIGO. For some reason the associated Como that was organized by Christian under the same processes. The web report was not an ARL report although Moller who then invited Peter Havas pages for these program can be found Moshe Carmeli from ARL wrote the and me to spend a month in Copen- here: http://sites.nationalacademies. introduction and the three organiz- hagen. In the fall of ’61, I returned to org/PGA/RAP/index.htm, http://sites. ers are listed as editors. With regard London to write up the paper on con- nationalacademies.org/PGA/Fellow- to the organization of the conference, servation laws which was sent to John ships/AFRL/index.htm.” Moshe wrote: Synge in Ireland as the referee. While I was away, Roy was left in Note that the program began in 1965, “The Relativity Conference in the charge. Joe Schell left for a teaching two years after I left ARL and involves Midwest was held in Cincinnati position in Florida and Roy brought in all Air Force Research Laboratories. from June 2–6, 1969 and was spon- Stuart Fickler who had worked with In the spring of 1963, I was offered sored jointly by the Aerospace Dick Arnowitt on quantizing the Yang- a position at Syracuse University and, Research Laboratories and the Uni- Mills field. When I returned in January as a result, Roy accepted a position in versity of Cincinnati. During 1969, 1962, Roy and I demonstrated that the Austin with Alfred Schild. In the fall the Aerospace Research Laboratories Maxwell field of an accelerating electric of 1963, Stu Fickler was left in charge celebrated the twentieth year of its charge had the asymptotic behavior that and in 1965 he added Lou Tamburino, existence and the University of Cin- exhibited the fall off of the algebraically Jeff Winicour, as Air Force employees cinnati celebrated its sesquicenten- special field. This was to exhibit a sim- and, in 1967 Moshe Carmeli. I think it nial year. Because of the extended ple example of the Petrov classification is worth quoting Jeff: interests of the Aerospace Research

10 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter Laboratories in the Theory of Rela- Science Foundation. Senator Michael It has been a great pleasure for me tivity and the recent arrival at the Mansfield added the amendment to the to relive my connection with the Aero- University of Cincinnati of one of bill that required in-house research in space Research Laboratory. I benefited the conference organizers, it was felt science by the military to have specific from comments about ARL not only that sponsoring a National Confer- relevance to its mission. At the time, from Jeff Winicour, but also from David ence on Relativity designed pri- general relativity was not considered Robinson for information about post- marily for participation by Ameri- relevant to the military. Not long later, docs and both for critical remarks of a can scientists would represent a GPS systems appeared and the mili- draft. Sadly, in the absence of the Man- worthwhile contribution to the joint tary versions made use of GR. Perhaps sfield amendment, the program at ARL celebrations.” some of the technology developed could have existed happily alongside through gravitational astronomy will the NSF and other support programs. Among the most important things find application as well. And future The end of this program was a loss to to come out of ARL are the publica- space exploration will make use of GR the Air Force of a particular skill as tions of the reports that resulted from as well. However, for many of us, the well as an entry to an important area the research supported. These were increase in our understanding of the of research. widely distributed in gray covers and universe is our reward for engaging in were freely available from the Armed gravitational research. Notes and References Services Technical Information Agency When the gravitational program [1] Professor Goldberg offered this article for publi- (ASTIA). The largest report, 459 pages, ended at ARL, Jeff Winicour went to cation in the summer of 2020. came from the Bondi group in London. Pittsburgh and Moshe Carmeli went to [2] Cecile M. DeWitt and Dean Rickles, eds. The Role It covered the period from 1961-64. It Beer Sheva University in Israel. Stuart of Gravitation in Physics, Max Planck Research contains the work of people who were Fickler and Lou Tamburino remained Library for the History and Development of at King’s College London, who were at the Wright Patterson Air Force Base, Knowledge, Open Access (2011). visitors, or were passing through. but at different laboratories. Unfortu- [3] Robert Lalli, Building the GRG Community dur- The gravitational program at ARL nately, Moshe, Stu, and Lou have died ing the Cold War: Communication Channels and Institutional Frames in Transition (1955-1975), came to an end in 1972 due to an and could not contribute information Springer Briefs in the History of Science and amendment to the bill that greatly about the last ten years of the existence Technology (2017) increased the budget of the National of the program.

The Indian contribution to the physics of black holes: 2020 Nobel Prize

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French mathematician Pierre Simon Chandrasekhar mass limit Laplace in 1796. They argued that if an object was very massive and dense, its The modern story begins with Sub- gravity would be so strong that even rahmanya Chandrasekhar who, after light could not escape from it Such an finishing his B.Sc. in Madras in 1930, object if it exists would be all dark and left for Cambridge, England for higher invisible, as no light can come from studies. On his voyage to Cambridge it. This follows from the very simple he did interesting calculations on white back of the envelope calculation in the dwarfs. It was believed then that all Newtonian gravity. The escape veloc- stars would end their life by becoming ity is given by equality of kinetic and a white dwarf—a final abode. This is potential energy of the escaping par- a very enigmatic object which sup- ticle, mv2/2= GmM/R giving v2 = 2GM/R ports itself against the force of grav- in the usual notation. When it equals the ity because of the pressure exerted by velocity of light, then light will not be electrons. In his mathematical inves- able to escape out. The radius of such tigation of such objects, the young an object would be, R = 2GM/c2, which Chandrasekhar combined Einstein’s would trap all the light and turn abso- theory of special relativity and the then lutely black—a black hole. Just to set new theory of quantum mechanics. He the scale, the escape velocity for Earth made the startling discovery in 1931 is 11 km/sec while the velocity of light that there is a maximum mass which is incredible 300,000 km/sec. If the Sun a white dwarf can have. This is about has to become a black hole, its entire 1.4 times the mass of our Sun. A white mass has to be squeezed into as small a dwarf with mass greater than this value, radius as 1.5 km. now called the Chandrasekhar mass Naresh Dadhich

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 11 limit, must necessarily collapse to a humanity. As mass further increases, cosmological in character, rather than a smaller size. This was an outstanding like electron, neutron degeneracy could collapsing cloud) (collapsing)[3] under breakthrough discovery which had set in—neutron pressure is no longer its own gravity. Unfortunately he died shattered the quiet, peaceful abode of sufficient to counter balance gravita- soon after on the operation table, while eternal rest for a star at the end of its tional pull to retain stable configuration being operated for hernia. A year later, evolutionary journey. of the neutron star. It turns out that this Robert Oppenheimer and David Sny- Chandrasekhar’s mentor and friend, happens when the star’s mass exceeds der[5] obtained the same solution as Datt Arthur Eddington from Cambridge, about 3 solar mass. This limit is not did, and had also matched the interior who was the most creative and influ- as sharp as the Chandrasekhar limit solution with the exterior Schwarzs- ential astrophysicist of the day, did because we do not understand interior child vacuum solution at the collaps- not for some strange unfathomable of the neutron star well and definitive ing boundary. It was truly a model of reason accept this brilliant discovery enough, in particular its equation of homogeneous gravitational collapse and criticized it strongly. The argument state which is a relation between pres- of a star-like object that proceeded was more rhetoric than objective and sure and density. uninterrupted down to the singularity, rational when Eddington surmised that If a neutron star is more massive where spacetime curvatures and energy he believed that there would exist some than this limit, it must collapse indefi- density diverge. It is famously known law of Nature that would prevent this nitely as there is no other kind of pres- as the Oppenheimer–Snyder collapse kind of catastrophe to occur. Even so, it sure available in the present theory in the literature. does not take away anything from the to resist it. It collapses right down to Those were the Second World War new light the monumental discovery zero size and infinitely large density years which had made the exchange of has shone on evolutionary track of a —singularity. Even before the object scientific information difficult in general, star. Chandrasekhar, however, had the reaches this singular state, it would and more so from India. Due to this rea- last laugh when he was at long last pass through a stage R = 2GM/c2, where son, and the sad and untimely demise of awarded the Nobel Prize in 1983 a good light gets trapped and cannot escape. Datt, his contribution remained unsung half a century after the discovery. The Michell–Laplace black hole would until 1999, when the Journal of General Stars consume nuclear fuel to pro- be formed. Relativity and Gravitation[6] reprinted duce energy that they emit as light and the original paper with an Editorial Black holes in Einstein’s theory heat. When all nuclear fuel is exhaust- commentary in its series on ‘Golden ed, i.e. temperature is no longer high So far we have discussed this phe- Oldies’. It would perhaps be appropriate enough for nuclear fusion to continue, nomenon in the Newtonian gravity. to acknowledge Datt’s contribution to the star collapses to a smaller size into What happens in Einstein’s theory the result that laid the foundation for a a cold state of white dwarf, which is of gravitation, where gravitation is black hole formation in general relativity entirely supported against gravity by beautifully synthesized into spacetime by naming it the Oppenheimer–Snyder– electron pressure. What Chandrasekhar geometry? It is described by curvature Datt (OSD) collapse. had calculated was the limit on electron of spacetime and hence is no longer an Here one may raise the question pressure—electron degeneracy, that external force but an integral part of the whether occurrence of singularity is the could counter gravitational pull due to geometry of spacetime. artefact of special properties of homoge- mass of a white dwarf. It turned out that In a simple intuitive way it could be neity and isotropy on the one hand and according to the theories of relativity understood as follows: Einstein’s law spherical symmetry on the other? and quantum mechanics, electron pres- of gravitation is the Newtonian inverse Raychaudhuri equation sure cannot sustain any mass greater square law in curved space instead of than 1.4 solar mass. This is how the flat space[3]. This makes a profound In 1953, Amal Kumar Raychaud- Chandrasekhar limit was discovered. impact on our understanding of the huri[7], when he was a lecturer in When electrons have given way, the phenomenon we are discussing. Ashutosh College, Kolkata, obtained a next avenue of resistance could then Since the velocity of light is univer- remarkable equation, which bears his come from neutrons. sally constant, hence it cannot change name, governing evolution of a system under any circumstance. The only way of particles according to Einstein’s theo- Gravitational collapse it could be trapped and confined is to ry of gravitation. It is the Raychaudhuri What happens when a star cannot make space curved so that it cannot equation that establishes in all generality end its life as white dwarf because it propagate out. This is precisely what the profound result that the occurrence is too massive for that? It turns out happens in general relativity. It is the of a singularity is inevitable in gen- that as a star continues its collapse, space curvature that gives rise to the eral relativity. It may be noted that the it eventually becomes so dense that bizarre phenomenon of a black hole. special conditions of homogeneity and almost all matter in it is converted into This is a more profound and geometric isotropy, and of spherical symmetry of neutrons. These neutrons can likewise object than what was conceived by the OSD collapse have been lifted-off, exert pressure to counter the gravita- Michell and Laplace. and the Raychaudhuri equation makes tional collapse giving rise to a stable In 1938, Bishveshwar Datt[4] of Kol- no reference to any symmetry and nature configuration, and the object so formed kata, India, was to find an exact solution of matter distribution, except of course is called a neutron star. Such an object of Einstein’s equation of expanding positivity of matter energy. It was the is so dense that just a spoonful of its (the solution described an expanding key to what was to follow a decade later matter would weigh the same as all of cloud without boundary was therefore in terms of the singularity theorems.

12 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter In the mid 1960s, Penrose building behaviour of various physical systems, be produced and would be observed on the Raychaudhuri equation and like collapsing stars or the expanding through the ringdown process. employing global analysis techniques Universe. And finally we have various In 2015, gravitational waves were of topology and differential geometry important, useful and interesting results detected in the LIGO observatory, win- made the profound prediction that for- which follow from the equations. Ein- ning the Nobel Prize in 1917 for Reiner mation of a black hole with a singularity stein’s theory of gravitation leads to Weiss, Kip Thorne and Barry Barish. at its centre is inevitable in Einstein’s the many profound and extraordinary The observed ring-down curve had theory of gravity. In collaboration with results on black holes, the big bang and uncanny and remarkable resemblance Stephen Hawking, he proved powerful expanding Universe, and so forth. The to the one obtained by Vishveshwara a theorems establishing the result math- role of the Raychaudhuri equation is good 45 years ago in the pre-sophisticat- ematically and rigorously. clear in this hierarchy. ed computer era. Though the Raychaudhuri equation In 1966, Fred Hoyle and Jayant In 1985, the Penrose process of ener- leads to the conclusion that singularity Narlikar[8] asked the question how gy extraction from a rotating black hole is inevitable in gravitational collapse massive a star must be so as to arrest was generalized[11] to include the pres- in general relativity, what the power- cosmic expansion of surrounding mat- ence of magnetic fields around the rotat- ful theorems of Penrose and Hawking ter to form a galaxy like structure? They ing black hole turning it into magnetic have shown is that as collapse proceeds, found that it must have a mass about Penrose process, by a young graduate before singularity is reached, trapped billion times the solar mass to form a student, Sanjay Wagh, a postdoc, San- surfaces would be formed from which galaxy of thousand billion solar mass. jeev Dhurabdhar and Naresh Dadhich, nothing, including light, could escape Thus they argued that the centre of the Pune University (now Savitribai Phule out. From this state onwards we can galaxy should harbour a supermassive Pune University, India). They showed receive no signal from the collapsing star (The term ‘black hole’ was coined that inclusion of magnetic field made object. The surface marking this prop- by John Wheeler a year later in 1967, in the process highly efficient and hence erty is called ‘event horizon’, indicating response to an audience question in a could serve as powering mechanism complete blockade of all information conference in New York, USA). This is for the most luminous objects, quasars and signals from external observer of purely an astrophysical argument for in the Universe[12]. It is gratifying that what is happening inside. Thus a black the existence of a supermassive object fully relativistic hydrodynamic flow hole is formed. It is this new perspective at the galactic centre. simulations beautifully bear out the illuminating formation of the darkest Ghez and Genzel, have shared the prediction made some 30 years ago[13]. It object in the Universe, and its inevitabil- Prize with Penrose for detecting a is considered as the most favoured pow- ity in Einstein’s theory of gravitation, is supermassive object, which is believed ering mechanism for quasars, active what has won Penrose the 2020 Nobel to be a black hole, at the centre of our galactic nuclei and ultra high energy Prize in Physics. galaxy. It is interesting that what Hoyle cosmic rays[14,15]. It is however worth speculating, had and Narlikar had predicted on astro- Setting the stage Raychaudhuri had the benefit of strong physical grounds over half a century and sophisticated mathematical backup, ago has actually been observed. It The 1960–70s were highly charged could he have perhaps discovered the should also be noted that they were times for great discoveries in rela- singularity theorems? the first to suggest that centres of gal- tivistic astrophysics and cosmology. In essence, the theorems explain axies should harbour supermassive Though the solution describing a black and demonstrate the process of black objects—a profound prediction and hole was obtained immediately after hole formation in terms of spacetime foresight. Einstein discovered his equation, yet geometry. Though the black hole Black holes are the simplest objects it was not understood as a black hole bizarre and exotic, yet it is, according as they could be fully characterized by until 1960s, a good 45 years later. As to Chandrasekhar, the simplest object in three parameters, viz. mass, rotation mentioned earlier, the term ‘black hole’ Nature, because it is a purely geometric and electric charge. Another young was invented by John Wheeler only construct. Indian graduate student, C. V. Vish- in 1967. In addition to the work cited in veshwara in Maryland, USA, took Roy Kerr obtained astrophysically the Nobel Prize, Penrose has several fancy to this exotic object in 1970 and the most remarkable and interesting important and path-breaking contribu- explored its various properties in a solution of Einstein’s equation describ- tions ranging from extraction of energy series of papers. The most remarkable ing gravitational field around a rotating from a rotating black hole, to the tran- and important among them[9,10] was black hole. On the other hand was the sition from pre- to post-big bang state the one that showed how a black hole, observation of incredibly luminous of the Universe. He has also worked which is purely a geometric object, rings objects, quasars that give out ener- extensively on the interface between like any other object when struck by gy ten orders of magnitude of stellar science and philosophy, dwelling on the matter. It rings down before it settles luminosity. deep questions of physical reality and down to its original state. This proves The crowning glory was of consciousness. two important properties: one, stabil- course the momentous discovery of The order of profoundness in phys- ity of a black hole under perturbations the cosmic microwave background ics proceeds as follows: At the top is the and second, as and when collision of a radiation at temperature 3 K, which discovery of a new law of physics. Then black hole occurs with another black was the greatest prediction and the come the equations that govern the hole or star, gravitational waves would distinguishing feature of the big bang

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 13 227 theory of the Universe. The Universe Acknowledgement [10] C. V. Vishveshwara, Nature, 1970, , 936 had a singular beginning in a hot big I thank Ajit Kembhavi and Abhay [11] S. Wagh, S. Dhurandhar and N. Dadhich, Ap J, bang, and the observed microwave Ashtekar for useful discussions. 1985, 290, 12. radiation is carrying that message and [12] S. Parthasarthy, S. Wagh, S. Dhurandhar, and N. signature. References Dadhich, Ap J, 1986, 301, 307 The stage was thus set for a great [1] This article is a reprint of the original that [13] R. Narayan, J. McClintock and A. Tchekhoskov, discovery and prediction that formation appeared in Current Science, 2020, 119, 2030. It Relativity and Gravitation: 100 Years After Einstein of a black hole and consequently, the is reproduced with the permission of Current in Prague (eds. J. Bicak and T. Ledvinka), Max Science. Planck Research Library for the History and central singularity are inevitable and Development of Knowledge, Open access Edi- [2] R. Penrose, Phys. Rev. Lett., 14, 57 distinguishing features of Einstein’s tion, Berlin, Germany, 2013, p. 523. [3] N. Dadhich, Curr. Sci., 2015, 109, 260 general relativity. [14] N. Dadhich, B. Ahmedov and Z. Stuchlik, Mon. It is gratifying to note that the two [4] B. Datt, Phys., 1938, 108, 314 Not. R. Astro. Soc., 2018, 478, L89 purely general relativity Nobel Prizes, [5] R. Oppenheimer and D. Snyder, Phys. Rev., 1939, [15] A. Tursunov, Z. Stuchlik, M. Kolos, N. Dadhich one for detection of gravitational waves 56, 455 and B. Ahmedov, Ap J, 2020, 895, 14 in 2017 and the present one for predic- [6] B. Datt, Gen. Rel. Grav., 1999, 31, 1619 tion of the formation of a black hole and its detection at the galactic centre, [7] A. K. Raychaudhuri, Phys. Rev., 1955, 98, 1123 had a strong Indian trail in the seminal [8] F. Hoyle and J. V. Narlikar, Proc. R. Soc. London, works of Datt and Raychaudhuri for the Ser. A, 1966, 290, 177 former, and Vishveshwara for the latter. [9] C. V. Vishveshwara, Phys. Rev., 1970, 1, 2870

March Session Report: “Farm Hall Revisited”

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Weizsäcker, used them to demonstrate energy and nuclear weapons during the Third Reich, and one of the ten their apparent innocence on all counts. World War II. A controversy has raged German internees in Farm Hall. There Dahn’s talk explored how a seemingly since the end of this war over Heisen- Weizsäcker was not only one of the authoritative text has been used to sup- berg’s understanding of how an atomic younger generation, but also someone port such differing perspectives, inves- bomb would work, ranging from accu- who dominated the discussions, in tigating a phenomenon all too familiar sations of incompetence to claims of particular those of political nature. Just in 2020: how apparently incontrovert- resistance against Hitler, with several after Hiroshima he argued that “the ible evidence can be spun to support a other variants in between. Walker’s talk peaceful development of the uranium variety of viewpoints. The meaning and explained what we do and do not know engine was made in Germany under the interpretation of the Farm Hall record- about this, including a suggestion as to Hitler regime, whereas the Americans ings have been contested since their what questions we should be asking. and the English developed the ghastly creation in 1945. The last talk was given by Dieter weapon of war.” The time he spent in Mark Walker is the John Bigelow Hoffmann, researcher emeritus at the Farm Hall also became instrumental for Professor of History at Union College Max Planck Institute for History of Sci- his thinking about the political respon- in Schenectady, NY and along with ence in Berlin, and editor of the German sibility of scientists and in particular of Christian Forstner is the co-editor of version of the Farm Hall transcripts, physicists during the atomic age. It was Biographies in the History of Physics: Operation Epsilon. Die Farm-Hall-Proto- no coincidence that he became one of Actors, Objects, Institutions (Cham: kolle oder Die Angst der Alliierten vor der the main initiators of the so called Göt- Springer: 2020), including the chapter deutschen Atombombe (Berlin: Rowohlt, tingen declaration of 18 (West)German by Walker: “A Biography of the Ger- 1993), which will appear soon in a new atomic physicists against the develop- man Atomic Bomb.” His talk, “Farm second edition. Hoffmann spoke on ment of nuclear weapons in Germany Hall: Did Heisenberg Understand How “Carl Friedrich von Weizsäcker and in 1957, and his work as a pioneer of Atomic Bombs Worked?” examines Farm Hall,” discussing the central freedom- and conflict-research, which the Nobel laureate, one of the found- place of Farm Hall in the life and work shaped the last decades of his academic ers of quantum mechanics, and one of this student, colleague and friend of life, was also rooted in the discussions of the most important scientists in the Werner Heisenberg, leading physicist and contemplations of Farm Hall. German research project into nuclear of the German nuclear project during

14 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter In Memoriam: Joshua N. Goldberg

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it had been known that all algebraically overarching principle was still lacking, special solutions of Einstein’s vacuum and in particular, “anything we find equations possessed shear-free null may be in conflict with general covari- congruences. The theorem proved the ance and I’m not, and I hope that my converse. friends are not die-hards so that they’ll New discoveries did of course not insist that general covariance is an ulti- cease on his return to Syracuse. Dis- mate requirement that they refuse to putes on the production and descrip- give up in any case”[12]. History will be tion of gravitational waves persisted. the ultimate judge! Null geodesics and null surfaces also remained a focus. Much was inspired Notes and References by Sach’s pioneering research in which [1] Oral History interview of Joshua Goldberg by Petrov types fall off along null rays Dean Rickles and Donald Salisbury, March 21, with varying inverse powers of the 2011, https://www.aip.org/history-programs/ D. Salisbury, Joshua Goldberg, and niels-bohr-library/oral-histories/34461 radial coordinate. It was natural in this D. Rickles – Syracuse, March, 2011 context to adapt the Newman-Penrose [2] D. Salisbury, A. Ashtekar, and D. Robinson, “Joshua N. Goldberg” in D. Malafarina and S. formalism to the investigation of the Scott, eds., The Golden Age of Space-time, (2021) asymptotic behavior of fields, and this self-dual gravitational connection that led to his most cited work[6]. In 1976 put the loop quantum gravity approach [3] J. N. Goldberg, “Gravitational radiation”, Phys. Rev., 99, 1873 (1955). he co-authored an influential paper on a firm footing[10]. with Jürgen Ehlers, Havas and Arnold Josh’s role as an administrator of [4] Interview in Columbus, Ohio, April 2018 Rosenblum that summarized the inad- Air Force funding in general relativity [5] J. N. Goldberg and R. K. Sachs. “A Theorem equacies of all the current gravitational is well known and much appreciated. on Petrov types”, Acta Physica Polonica, 22, [7] 13 (1962); reprinted in Gen. Rel. Grav., 41, 433 back reaction procedures . Also, his Less well known are his achievements (2009). familiarity with Ted Newman’s asymp- as the Chair of the Syracuse Physics totic H- space and Penrose’s twistor Department where with some internal [6] J. N. Goldberg, A. J. Mcfarlane, E. T. Newman, F. Rohrlich, and E. C. G. Sudarshan, “Spins program led him to discover a new geo- opposition he managed the installation spherical harmomics and eth”, J. Math. Phys., metrical approach to Abhay Ashtekar’s of new laboratories within the physics 8, 2155 (1967). gravitational field variables. The out- building. And I personally thank him [7] J. Ehlers, A. Rosenblum, J. N. Goldberg and P. come in 1988 was a new derivation of for having extended my teaching assis- Havas, “Comments on gravitational radiation the Ashtekar constraint algebra and the tantship appointment beyond the usual damping and energy loss in binary systems”, associated symmetry transformations[8]. six year limit! Astro. Phys. J., 208, L77 (1976). Abhay had first joined the relativity He was also, of course, an active [8] J. N. Goldberg, “Triad approach to the Hamil- group at Syracuse in 1980, assuming a presence in weekly seminars and regu- tonian of general relativity”, Phys. Rev. D, 37, position as Assistant Professor that had lar work sessions with relativity gradu- 2116 (1988). been created with an NSF grant that ate students, resident post-docs, and [9] J. N. Goldberg, D. C. Robinson and C. Soteriou, Josh had marshaled through the system frequent visitors. I recall many instances “Null hypersurfaces and new variables”, Class. while serving as the Physics Depart- in which he pursued calculations at Quant. Grav., 9, 1309 (1992). ment Chair. It was natural, given the the relativity group blackboard. His [10] J. N. Goldberg and J. Lewandowski and C. Stor- long-standing emphasis on the Syracuse demeanor was always calm, confident, naiolo, “Degeneracy in loop variables”, Comm. 148 group on the canonical quantization of and poised. He radiated a non-preten- Math. Phys., , 377 (1992). Einstein’s theory, that in the late 1980’s tious self-confidence and never hesi- [11] See D. Salisbury, “Toward a quantum theory Josh would turn his attention, with col- tated to engage if he disagreed. There of gravity: Syracuse 1949-1962”, in A. Blum, R. Lalli, and J. Renn, eds., The Renaissance of General laborators David Robinson and Chrys was never any doubt that he was simply Relativity in Context (2020). Soteriou, to the canonical formalism on seeking the truth. [12] Interview in Berlin, Germany, December 2015. null surfaces[9]. Finally, as Abhay has We did indeed disagree on an testified[2], Josh produced in 1992 a land- issue that had occupied the Syracuse mark paper with Jerzy Lewandowski relativity school since Bergmann’s and Cosimo Stornailo dealing with the arrival in 1947[11]. Josh believed that an

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 15 March Session Report: “The Author in Dialogue: Jeffrey Bub’s Bananaworld”

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described by a given correlation array, and he discussed the polyhedra that the correlations associated with such raffles describe. He showed how the facets of these polyhedra more and more closely approximate an elliptope as the number of outcomes per variable increases, but do not achieve it except in the limit of the number of outcomes per variable. Janas then turned to quantum mechan- ics, as applied to banana peeling and tasting experiments, and introduced a formalism for describing banana peel- ing directions, the angles between them, and their associated (anti-)correlation coefficients. He then presented the Gram matrix describing the correlations Michael Janas screenshot between peeling angles, and derived an inequality constraining the values of the anti-correlation coefficients. The assigning values to the summands. He the more important one for the Everet- inequality describes an elliptope. Janas then clarified that the claim: “quantum tian (“many worlds”) interpretation, noted that in quantum mechanics the mechanics is all about information” and that Everettians call the “small” elliptope is achieved for any number of is properly understood as indicating problem the preferred basis problem. outcomes per variable (i.e., regardless of where the conceptual novelty of the Cuffaro welcomed these comments the value of spin). Janas then explained theory is located, i.e., in the kinematical and elaborated further on the relation that the elliptope inequality is actually constraints that the theory imposes on between the view defended in Under- a generic constraint (first discovered in every specific system it describes, and standing Quantum Raffles and Everett, the 19th century) on the correlations illustrated this by comparing classical noting that Everett seems committed between three arbitrary random vari- phase space with Hilbert space. Cuffaro to reifying Hilbert space. Michel Jans- ables. He then discussed how to apply then clarified that what is real, on the sen then mentioned historical work by the generic version of the inequality to information-theoretic interpretation, are Ofer Gal and Raz Chen-Morris on the quantum mechanics, noting that what the values of observable quantities. This conceptual history of optics, and asked the general (“from without”) deriva- is also true in classical theory, but clas- for Cuffaro’s thoughts on Henderson’s tion and the derivation “from within” sical theory’s kinematical constraints discussion of pragmatism. Cuffaro com- quantum mechanics have in common invite an interpretation of these values mented that he endorsed appealing to is an appeal to Hilbert space, a Hilbert as originating in observer-independent pragmatism as a counter to criticism space of random variables and a Hilbert properties, while quantum theory’s (in the way Henderson clarified in her space of observables, respectively. In kinematical constraints do not. He then response to Bub’s question). He also the question period Janas was asked discussed the “big” and the “small” mentioned Kantianism and other alter- by a member of the general audience measurement problems (arising from natives to the “representationalist” view whether he had considered computing irreducible indeterminism and contex- besides pragmatism that could play Hausdorf fractal dimensions and using tuality, respectively). Cuffaro explained the same role. Henderson then asked them to clarify physical meaning. Janas that the labels (originally due to Bub Cuffaro whether privileging values answered that that doesn’t seem to be and Itamar Pitowsky) are ironic, and of observable quantities would invite applicable here. that the “small” problem is the more the charge of instrumentalism. Cuffaro In the third talk of the session, Cuf- interesting one as it illuminates the noted that values are not simply sense faro began his defence of the infor- structure of the theory, but ultimately impressions, and that they include both mation-theoretic interpretation laid both it and the “big” problem are “not dynamical and fixed quantities. He also out in Understanding Quantum Raffles bugs but features”. In the question denied that values of observable quan- by noting that the reason quantum period, Bub noted that the “big” label tities exhaust what we can say about mechanical systems (unlike local hid- was indeed meant ironically but noted reality, even if they are primary. Bub den-variable models) in the Mermin set- that “small” has both an ironic (because then added that physics seems to be up saturate the elliptope, for any value it is more important) and a non-ironic telling us that indeed we do have to be of spin, is that in quantum mechanics (because it is tractable) meaning. Bub “a little bit” instrumentalist, and that he we can assign a value to a sum without also noted that the “big” problem is doesn’t think that instrumentalism is a

16 Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter bad thing, per se; i.e., if quantum theory tells us that there are certain constraints on how we can represent reality then we should believe it. In the final talk of the session, Bub began by describing his initial motiva- tion for writing Bananaworld, namely to highlight entanglement as the core feature of quantum theory that sets it apart from classical theory. But as he continued to develop the book, he found that the geometry of correlations began to emerge more prominently; i.e., the idea that classical correlations can be mathematically described as a subset of quantum correlations, which in turn can be described of as a subset Michael Cuffaro screenshot of all possible no-signaling correlations, and so on. Bub’s intention in the book was not so much to say but to show that non-classicality ultimately stems from non-commutativity / non-Booleanity, something that can be asserted in a precise mathematical sense. But noted that for George Boole, a Boolean algebra captures what Boole called “the condi- tions of possible experience,” and that the shift from classical to quantum the- ory amounts to a shift from a Boolean algebra of subsets of a set (phase space) to a non-Boolean algebra of subspaces of a vector space (Hilbert space), where by a “non-Boolean algebra” we mean a family of intertwined Boolean algebras. Bub then noted that John von Neumann once wrote that quantum probabilities Jeffrey Bub screenshot are sui generis, and “there from the start”. Bub endorsed this, defending the view that quantum mechanics is about then asked what visualisability is, and called the measurement problem the probability, in the sense of being a new why quantum mechanics is puzzling. most interesting and difficult part of framework for dealing with probability, He noted that what is puzzling from the theory. He then raised the ques- one in which new sorts of nonlocal cor- a Boolean perspective is that measure- tion, how does what we do when we relations associated with entanglement ment in a non-Boolean theory is not measure select a basis in Hilbert space? are possible. Bub then mentioned that passive but produces a change in the Does this require a kinematical or a he regrets attaching the label “infor- description of a phenomenon. Measure- dynamical answer, or a combination of mation-theoretic” to his interpretation ment represents a loss of information, both? For Bub the dynamical answer of quantum mechanics. Upon reflec- a kind of Boolean “snapshot” of an amounts to a consistency proof. In the tion, what he always really meant, underlying non-Boolean description. question period Bub elaborated on the and should have said, is that quantum (Bub mentioned that Wolfgang Pauli history of Bananaworld as well as on the mechanics is about probabilities in the once called observation an “irrational, “serious comic about entanglement”, same way that special relativity is about unique actuality”.) Bub then asserted Totally Random, that he co-authored with spacetime. Bub then moved on to the that quantum probabilities do not his daughter, Tanya Bub. According to topic of visualisability, and mentioned represent ignorance in the normal Bub, Bananaworld was intended as a how in a footnote in his 1926 paper on sense, but a new sort of ignorance popular book but in the end the result wave mechanics, Erwin Schrödinger about something that doesn’t yet have was somewhere in between a popular wrote that he was “repelled” by matrix a truth value, that requires us to act and book and a scholarly book. Totally Ran- mechanics because of its lack of visual- do something before nature supplies dom was partly intended to remedy this, isability. He also noted that Heisenberg a truth value, and removes the truth and is truly a popular book. was “repulsed” with Schrödinger’s values of incompatible propositions theory and had a low opinion of his col- not belonging to the same Boolean alge- league’s appeal to visualisability. Bub bra. Bub mentioned that Schrödinger

Volume XIV, No. 6 • Spring 2021 • History and Philosophy of Physics Newsletter 17 Review of Proving Einstein Right

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attended a lavish lunch in Paris and the difficulties of developing fragile, Reader-friendly features include then a birthday party for twelve-year- cumbersome photographic glass plates several photographs and a wealth of old Ruth Turner, daughter of astrono- in the field. We sample the expedition’s detailed endnotes that connect the main mer H.H. Turner. They presented the costs to families due to long absences, narrative to interesting sidebar stories. girl with a box of chocolate bells….One such as missing a child’s birthday A map of paths of totality for the solar can only imagine the astronomer royal party back home far away. We learn eclipses of 1900-1922 is appreciated. and the comical ‘Atky’ poring over the histories of landscapes darkened by Gates and Pelletier bring this epic tale to the candies at some tiny boutique, the the eclipse—including histories dark- closure by relating the 1919 expedition’s Gobron-Briellié parked out front.”(41) ened in deeper ways such as human aftermaths and how the principal actors Embarking on the 1919 expedition, enslavement on the cocoa plantations spent the rest of their days. In Proving we see the astronomers grow anxious of Príncipe and the rubber plantations Einstein Right the reader comes to care as their precious instrument crates have of Sobral. about them as human beings. That is a yet to arrive at the Liverpool dock as Finally in 1919 the weather, equip- gracious accomplishment for any his- the time for departure aboard the 400- ment, and eclipse align to yield good torical narrative. foot steamer Anslem draws near. In the images at last. Some plates come out As in any large story, besides the field, we see distinguished astronomers better than others, but the results are principal actors we meet many others commuting between their lodging and consistent with Einstein’s predicted whose roles range from family members the observing site on a locomotive cow deflection and rule out Newton’s. and government officials to professional catcher. With the observing camp in Back in London, we see the reactions colleagues and volunteer assistants. If readiness, while awaiting eclipse day of participants at the joint meeting of a second printing is ever considered, we accompany our heroes on a moun- the Royal Society and the Royal Astro- I suggest including an annotated list tain excursion in a Studebaker provided nomical society where, under a portrait of main and secondary characters, by the host national government—but of Newton, the expedition’s results are perhaps as an appendix. Such a list after the chauffer’s aggressive hard officially announced and discussed. appears in Walter Isaacson’s recent driving overheats the engine and blows Not all listeners are thrilled—Sir Oliver biography of Albert Einstein, where it out two tires, the astronomers elect to Lodge, a “committed ‘ether man’…rose is fitting to see Gates included in the hike back to camp.(213) and left the meeting” —but we cannot acknowledgments. As in all great adventures, difficul- help feeling some pity for the grieving While reading Proving Einstein Right, ties and disappointments occur. Under Sir Lodge when we learn the reason the reader will have no trouble translat- what were initially perfect conditions, for his persistent commitment to the ing the words on the pages into vivid we share the discouragement when an ether.(241) mental pictures, feeling like he or she eclipse is rained out. While enroute to One day while teaching a general- tags along on these eclipse expedi- 1914 eclipse sites, World War I breaks education science class, I found it tions as a companion of Eddington and out. Hoping for the best, as the coun- helpful to borrow a passage from Dyson, Perrine and Campbell and all try mobilizes all around us we press Proving Einstein Right to illustrate the the rest, including sharing in Einstein’s on deep into Russia, only to be taken distinction between laws of nature and hopes and troubles as he offers encour- into custody and our instruments con- theories. Illustrating the distinction by agement from Germany. We see from fiscated. For the June 1918 eclipse Wil- metaphor, Gates and Pelletier imagine behind the scenes what it took to bring liam Campbell of the Lick Observatory a “Law of Sunrise”(238), articulat- everything together in making possible is obliged to make do with borrowed ing the observed pattern, for which a the proud announcement of 1919. Prov- equipment as his best instruments lan- “Theory of Sunrise” explains the Sun- ing Einstein Right offers an illuminating guish somewhere on their slow journey rise Law in terms of Earth’s spin. Prov- and enjoyable journey—or rather a back from Russia—then on eclipse eve ing Einstein Right contains passages collection of journeys. Indeed, I imme- Campbell learns that his son Doug- that assist pedagogical discussions on diately read it a second time so I could las, a WW I flying ace, has been shot philosophy of science, in addition to experience the adventures and intel- down, his fate then unknown. Hours shining an engaging light on the his- lectual companionships all over again. after the 1919 eclipse, we appreciate tory of physics and astronomy.

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prevents the re-introduction of air. In experiments (http://www.sites.hps. address scientific questions neglected such a setup the water produces fewer cam.ac.uk/boiling/). in current specialist science. I regard and larger bubbles as it goes on boiling, The kind of historical (and philo- this as one of the functions of the his- its temperature reaching around 104°C. sophical) work that I have illustrated tory and philosophy of science. There It then continues indefinitely in a qui- here can be done about almost any item are clear implications of such work escent state with occasional explosive of scientific knowledge. The subject for science education and the public large bubbles bringing the temperature matter of my work has ranged from understanding of science. I think it is down slightly but not down to 100°C. early quantum physics and relativity very important that people have an I spent a whole summer boiling water, to Count Rumford’s “frigorific rays.” opportunity to experience the doing reproducing De Luc’s results from 1772 Currently I am completing a book titled of science, rather than just learning and devising my own experiments to How Does a Battery Work?, following knowledge created by others. Looking resolve various follow-up questions, the development of electrical science to the history of the most basic items of and learning from the modern spe- that followed Volta’s invention of the scientific knowledge gives us a body of cialist work as well. The main results battery. I call my brand of research manageable science that any interested from this work are summarized in an “complementary science”: historical people can experience and enjoy. online paper with some video clips of and philosophical investigations that

FHPP News

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made distinguished achievements. Prof. Peng, a number of academic activities their institutions, to organize their own Shenghua Hu (deputy editor-in-chief of will be held. activities, such as outreach talks, lab Science Press and director of the Journal tours, debates, interviews, etc., to cel- Publishing Center) and Prof. Baichun World Quantum Day ebrate the World Quantum Day around Zhang (former director of the IHNS- By Yasser Omar, University of Lisbon the World. The World Quantum Day is CAS) gave a presentation on “Shoujing celebrated on April 14, a reference to Wang and Early Quantum Mechanics The World Quantum Day is an ini- 4.14, the rounded first digits of Planck’s Research”. Shoujing Wang’s work on tiative from quantum scientists from constant: 4.135667696×10^−15 eV.s. solving hydrogen molecules was one 65+ countries, launched on 14 April Even though this year only one sym- of the earliest PhD theses on quantum 2021 as the countdown towards the first bolic launch event was planned, there mechanics in the United States. global celebration on 14 April 2022. The was an overwhelming enthusiasm and, In addition, associate professor World Quantum Day aims at engaging despite the short notice, events were Jinyan Liu from the IHNS-CAS gave the general public in the understand- organized in Asia, Europe, Africa, South a shout introduction of the “Quan- ing and discussion of Quantum Sci- America, and North America, and the tum Century (2025)” Project and its ence and Technology, namely how it World Quantum Day web site had visi- forthcoming activities in China, which helps us understand Nature at its most tors from 120+ countries. includes a series of public lecture on fundamental level, how it helped us Preparations for the 2022 celebra- quantum science and technology in develop technologies that are crucial tion of the World Quantum Day are 2021, an international symposium on for our life today, and how it can lead now ongoing. Furthermore, the World the “History of Quantum Mechanics” to future scientific and technological Quantum Day supports and collabo- in 2023, and a symposium on the 70th revolutions and how these can impact rates closely with the Quantum Century anniversary of the Yang-Mills gauge our society. It is a decentralized and project. Albeit an independent initia- theory in 2024. In 2025, the Quantum bottom-up initiative, inviting all quan- tive, the World Quantum Day can act century, which coincides with the 110th tum scientists, engineers, educators, as a precursor, as well as a continuator anniversary of the birth of the found- historians, philosophers, communica- of the Quantum Century celebrations. ing director of the ITP-CAS, Huanwu tors, entrepreneurs, technologists, and

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