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Sun, 17 Jan 2021 16:24:01 GMTFeedCreatorClass 1.0 dev (follow.it)Is the Standard Model Just an Effective Field Theory?
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/391509584/15156" border=0 width="1" height="1" alt="Story 391509584" title="Story 391509584"> <p>An article by Steven Weinberg entitled <a href="https://arxiv.org/abs/2101.04241">On the Development of Effective Field Theory</a> appeared on the arXiv last night. It’s based on a talk he gave in September, surveys the history of effective field theories and argues for what I’d call the “SM is just a low energy approximation” point of view on fundamental physics. I’ve always found this point of view quite problematic, and think that it’s at the root of the sad state of particle theory these days. That Weinberg gives a clear and detailed version of the argument makes this a good opportunity to look at it carefully. </p>
<p>A lot of Weinberg’s article is devoted to history, especially the history of the late 60s-early 70s current algebra and phenomenological Lagrangian theory of pions. We now understand this subject as a low energy effective theory for the true theory (QCD), in which the basic fields are quarks and gluons, not the pion fields of the effective theory. The effective theory is largely determined by the approximate SU(2) x SU(2) chiral flavor symmetry of QCD. It’s a non-linear sigma model, so non-renormalizable. The non-renormalizability does not make the theory useless, it just means that as you go to higher and higher energies, more possible terms in the effective Lagrangian need to be taken into account, introducing more and more undetermined parameters into the theory. Weinberg interprets this as indicating that the right way to understand the non-renormalizability problem of quantum gravity is that the GR Lagrangian is just an effective theory.</p>
<p>So far I’m with him, but where I part ways is his extrapolation to the idea that all QFTs, in particular the SM, are just effective field theories:</p>
<blockquote><p>The Standard Model, we now see – we being, let me say, me and a lot of other people – as a low-energy approximation to a fundamental theory about which we know very little. And low energy means energies much less than some extremely high energy scale 10<sup>15</sup>−10<sup>18</sup> GeV.</p></blockquote>
<p>Weinberg goes on to give an interesting discussion of his general view of QFT, which evolved during the pre-SM period of the 1960s, when the conventional wisdom was that QFTs could not be fundamental theories (since they did not seem capable of describing strong interactions). </p>
<p>I was a student in one of Weinberg’s graduate classes at Harvard on gauge theory (roughly, volume II of his three-volume textbook). For me though, the most formative experience of my student years was working on lattice gauge theory calculations. On the lattice one fixes the theory at the lattice cut-off scale, and what is difficult is extrapolating to large distance behavior. The large distance behavior is completely insensitive to putting in more terms in the cut-off scale Lagrangian. This is the exact opposite of the non-renormalizable theory problem: as you go to short distances you don’t get more terms and more parameters, instead all but one term gets killed off. Because of this, pure QCD actually has no free parameters: there’s only one, and its choice depends on your choice of distance units (Sidney Coleman liked to call this dimensional transvestitism).</p>
<p>The deep lesson I came out of graduate school with is that the asymptotically free part of the SM (yes, the Higgs sector and the U(1) are a different issue) is exactly what you want a fundamental theory to look like at short distances. I’ve thus never been able to understand the argument that Weinberg makes that at short distances a fundamental theory should be something very different. An additional big problem with Weinberg’s argument is its practical implications: with no experiments at these short distances, if you throw away the class of theories that you know work at those distances you have nothing to go on. Now fundamental physics is all just a big unresolvable mystery. The “SM is just a low-energy approximation” point of view fit very well with string theory unification, but we’re now living with how that turned out: a pseudo-scientific ideology that short distance physics is unknowable, random and anthropically determined.</p>
<p>In Weinberg’s article he does give arguments for why the “SM just a low-energy approximation” point of view makes predictions and can be checked. They are:</p>
<ul>
<li>There should be baryon number violating terms of order $(E/M)^2$. The problem with this of course is that no has ever observed baryon number violation.</li>
<li>There should be lepton number violating terms of order $E/M$, “and they apparently have been discovered, in the form of neutrino masses.” The problem with this is that it’s not really true. One can easily get neutrino masses by extending the SM to include right-handed neutrinos and Dirac masses, no lepton number violation. You only get non-renormalizable terms and lepton number violation when you try to get masses using just left-handed neutrinos.</li>
</ul>
<p>He does acknowledge that there’s a problem with the “SM just a low-energy approximation to a theory with energy scale M=10<sup>15</sup>−10<sup>18</sup> GeV” point of view: it implies the well-known “naturalness” or “fine-tuning” problems. The cosmological constant and Higgs mass scale should be up at the energy scale M, not the values we observe. This is why people are upset at the failure of “naturalness”: it indicates the failure not just of specific models, but of the point of view that Weinberg is advocating, which has now dominated the subject for decades.</p>
<p>As a parenthetical remark, I’ve today seen news stories <a href="https://www.space.com/no-signs-supersymmetry-large-hadron-collider">here</a> and <a href="https://www.symmetrymagazine.org/article/the-status-of-supersymmetry">here</a> about the failure to find supersymmetry at the LHC. At least one influential theorist still thinks SUSY is our best hope:</p>
<blockquote><p>Arkani-Hamed views split supersymmetry as the most promising theory given current data.</p></blockquote>
<p>Most theorists though think split supersymmetry is unpromising since it doesn’t solve the problem created by the point of view Weinberg advocates. For instance:</p>
<blockquote><p>“My number-one priority is to solve the Higgs problem, and I don’t see that split supersymmetry solves that problem,” Peskin says. </p></blockquote>
<p>On the issue of quantum gravity, my formative years left me with a different interpretation of the story Weinberg tells about the non-renormalizable effective low-energy theory of pions. This got solved not by giving up on QFT, but by finding a QFT valid at arbitrarily short distances, based on different fundamental variables and different short distance dynamics. By analogy, one needs a standard QFT to quantize gravity, just with different fundamental variables and different short distance dynamics. Yes, I know that no one has yet figured out a convincing way to do this, but that doesn’t imply it can’t be done.</p>Thu, 14 Jan 2021 02:10:47 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110mmRHRtM11aQqnAxiD9qXc5Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oTChgKQX34XNVarious Links
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/391417790/15156" border=0 width="1" height="1" alt="Story 391417790" title="Story 391417790"> <p>Our semester at Columbia started earlier than usual this year, with first classes this week, my first class yesterday. This semester I’m teaching the <a href="http://www.math.columbia.edu/%7Ewoit/QM/spring2021.html">second half</a> of a year-long course on the mathematics of quantum mechanics. There’s a <a href="https://www.youtube.com/channel/UCdSEKN94Jo1xjUHVyfEfIjg">Youtube channel</a> with the lectures for the <a href="https://www.youtube.com/playlist?list=PLOaEOh8qMwDLoBJinaH3p31edODHdlb93">first half of the course</a>, and now also for the <a href="https://www.youtube.com/playlist?list=PLOaEOh8qMwDLeEdrwt3n8xLErYi9iQPY5">second half</a>. The course is largely following <a href="https://www.math.columbia.edu/~woit/QMbook/qmbook-latest.pdf">the textbook</a> I wrote based on teaching this is earlier years. The first lecture yesterday was a summary of a point of view on canonical quantization explained in the first semester and in the book. This point of view is essentially that Hamiltonian mechanics is based on a Lie algebra (functions on phase space with Poisson bracket the Lie bracket), and canonical quantization is all about the essentially unique unitary representation of (a subalgebra of) that Lie algebra. On Thursday I’ll start on the fermionic version of canonical quantization, which has a very much parallel structure, giving a super-Lie algebra and spinors.</p>
<p>A few other items:</p>
<ul>
<li>John Baez’s <a href="https://math.ucr.edu/home/baez/TWF.html">This Week’s Finds in Mathematical Physics</a> was an unprecedented project conducted over 17 years, providing a wealth of fantastic expository material on topics in math and physics. It started in 1993, and on its twentieth anniversary I wrote an appreciation (in an appropriate font) <a href="https://www.math.columbia.edu/~woit/wordpress/?p=5510">here</a>. John has now <a href="https://golem.ph.utexas.edu/category/2021/01/this_weeks_finds_150.html">announced</a> that this material has been typeset (2610 pages!) and he is editing it, to be released in batches. The first part is now available, on the arXiv as <a href="https://arxiv.org/abs/2101.04168">This Week’s Finds in Mathematical Physics (1-50)</a>. As I find time, I’m looking forward to reading through these, encourage everyone interested in math and physics to do the same.</li>
<li>Frank Wilczek has <a href="https://www.penguinrandomhouse.com/books/554034/fundamentals-by-frank-wilczek/9780735223790">a new book</a> out, and there’s <a href="https://www.quantamagazine.org/frank-wilczek-cracked-open-the-cosmos-20210112/">an interview with him at Quanta</a>. You can see a conversation between him and Brian Greene <a href="https://www.youtube.com/watch?v=v6YEKYIkrzI">here on Friday</a>.</li>
<li>Another physicist with a new book is Jesper Grimstrup, whose <a href="https://www.amazon.com/dp/B08SM9B82P/">Shell Beach: The search for the final theory</a> I’ve just finished reading and enjoyed greatly. The book is quite personal and non-technical, with topic Grimstrup’s life as a theorist pursuing a unified theory. His career story is quite interesting, giving insight into the ways academic theoretical physics is challenging for young theorists trying to pursue non-mainstream research programs. Several books have appeared in recent years aimed at putting this kind of physics research in a human and philosophical context, telling you what it has to do with the meaning of life. There’s some of that in this book too, of a much more compelling sort than what you see elsewhere. Grimstrup has a website <a href="https://jespergrimstrup.org/">here</a>, and in recent years has ended up leaving academia and trying to fund his research with donations. I can think of a lot worse things you could do with your money than <a href="https://www.paypal.com/donate/?hosted_button_id=N7UAWRUSG8LLQ&locale.x=en_DK">send him some</a>.
<p>I’m quite sympathetic to the underlying theme that he describes pursuing (together with Johannes Aastrup) in the book, that of bringing together the insights of loop quantum gravity and non-commutative geometry. More recently they’ve been working on some new ideas for formulating QFT non-perturbatively that seem worth investigating. There’s a survey blog post <a href="https://noncommutativegeometry.blogspot.com/2020/11/the-metric-nature-of-matter-guest-post.html">here</a>.</li>
</ul>
<p><strong>Update:</strong> Another bit of private math/physics funding news. The IAS has announced establishment of the <a href="https://www.ias.edu/news/2021/cpf-cross-disciplinary-program-in-innovation-established">Carl P. Feinberg Cross-Disciplinary Program in Innovation</a></p>
<blockquote><p>Scientific research at the Institute is traditionally driven by the collaboration and independent projects of a full-time Faculty and a revolving class of more than 200 researchers at various stages in their careers. The Carl P. Feinberg Cross-Disciplinary Program in Innovation will build on this successful model with the recruitment of mid-career scholars who have pioneered foundational developments in new areas. Bringing together scholars with such unique insights—which may not be obviously connected to the existing themes of the past 20 or 30 or 40 years—ensures that IAS will remain agile and responsive to new intellectual developments that do not yet fit the mold of what graduate students and postdocs generally know. In order to close this knowledge gap, the program will feature intense, focused workshops and “master classes.”</p>
<p>“Since its founding, the Institute has served as a world center for investigations into the fundamental laws of nature. We are currently in the middle of a grand symbiosis of ideas, from the equations of general relativity to the quantum information of black holes,” stated Robbert Dijkgraaf, IAS Director and Leon Levy Professor. “This revolutionary program will provide a dedicated space and the necessary flexibility to accelerate these exciting developments, and will surely forge new connections across fields.”</p></blockquote>Wed, 13 Jan 2021 19:35:20 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110l1rLPFTijzXHawZ12B-dU6Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_ofN8JMAZVFx9Martin Veltman 1931-2021
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/389487705/15156" border=0 width="1" height="1" alt="Story 389487705" title="Story 389487705"> <p>I heard today of the recent death of Martin Veltman, a theorist largely responsible (with his student Gerard ‘t Hooft) for showing the renormalizability of non-abelian gauge theories, a breakthrough crucial to the Standard Model that won both of the them the 1999 Nobel Prize. For the story of this work, the best source is likely <a href="https://www.nobelprize.org/uploads/2018/06/veltman-lecture.pdf">Veltman’s Nobel lecture</a>.</p>
<p>My one memory of meeting Veltman in person was when he visited Stony Brook at the time that I was a postdoc there (mid 1980s). There was a party at someone’s house, and I spent part of the evening talking to him then. What most struck me was his great passion for whatever it was we were talking about. One topic I remember was the computer algebra program <a href="https://en.wikipedia.org/wiki/Schoonschip">Schoonschip</a> (which Wolfram <a href="https://announcements.wolfram.com/1999/computer-algebra-pioneer-wins-nobel-prize/">acknowledges</a> as an inspiration for Mathematica). I vaguely recall that at that time Veltman had recently ported the program to a microprocessor and he was selling copies in some form. It also seems to me that one remarkable aspect of the program was that it was written in assembly language, not compiled from a higher level language. At the time I was doing computer calculations, but of a very different kind (lattice gauge theory Monte-Carlos). Since my own interests were focused on non-perturbative calculations, I wasn’t paying much attention to Veltman’s work, although I do remember finding his <a href="http://cds.cern.ch/record/186259/files/CERN-73-09.pdf">Diagrammar</a> document (written with ‘t Hooft) quite fascinating.</p>
<p>A comment that evening that really struck me was about students, in particular that “you give your students your life-blood!”. This seemed likely to have some reference to Veltman’s relations with his ex-student ‘t Hooft, but I’m pretty sure I didn’t quiz him on that topic.</p>
<p>Many years later, when I was trying to get <em>Not Even Wrong</em> published, I contacted Veltman and he was quite helpful. At the time he had recently published his own popular book about particle physics, <a href="https://www.worldscientific.com/worldscibooks/10.1142/5088">Facts and Mysteries of Elementary Particles</a>, which contained his own version of the Not Even Wrong critique:</p>
<blockquote><p>The reader may ask why in this book string theory and supersymmetry have not been discussed. . . The fact is that this book is about physics and this implies that theoretical ideas must be supported by experimental facts. Neither supersymmetry nor string theory satisfy this criterion. They are figments of the theoretical mind. To quote Pauli, they are not even wrong. They have no place here.</p></blockquote>
<p>That book is quite good, I strongly recommend it. May its author rest in peace.</p>Thu, 07 Jan 2021 00:00:12 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110lPeDzHWQzhEk6NAX1_5kxdJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oRerah-hxOT5DAU. String Theory
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/388806356/15156" border=0 width="1" height="1" alt="Story 388806356" title="Story 388806356"> <p>I first wrote <a href="https://www.math.columbia.edu/~woit/wordpress/?p=8061">here in 2015</a> about DAU, the unusual film project based to some extent on the life of Landau. Parts of the film first were shown in Paris early in 2019, and this past year started appearing on <a href="https://www.dau.com/en">the DAU website</a>. I’d been looking forward to seeing Gross, Yau, Rovelli and others in the film, so paid to watch one of the first parts, <a href="https://www.dau.com/en/dau-degeneration-18">DAU. Degeneration</a>, when it became available last year. It’s over six hours long, for a review, see <a href="https://www.theguardian.com/film/2020/apr/30/dau-degeneration-review-ilya-khrzhanovsky-russia">here</a>. I ended up doing a certain amount of fast-forwarding, was disappointed to only see Nikita Nekrasov and Dmitri Kaledin, none of the other math/physics world figures I had heard had participated.</p>
<p>DAU largely was funded by Russian oligarch Sergei Adoniev. For an excellent article discussing the project and its context in current Russian culture, see Sophie Pinkham’s article <a href="https://newleftreview.org/issues/ii125/articles/sophie-pinkham-nihilism-for-oligarchs">Nihilism for Oligarchs</a>.</p>
<p>There wasn’t much physics in DAU. Degneration, but evidently it plays a significant role in other parts of the film. <a href="https://www.dau.com/en/about-us">According to the DAU website</a>,</p>
<blockquote><p>Real-life scientists, who were able to continue with their research in the Institute, included: physicist Andrei Losev; mathematicians Dmitri Kaledin and Shing-Tung Yau; string theorist Nikita Nekrasov; Nobel-Prize winning physicist David Gross; neuroscientist James Fallon; and biochemist Luc Bigé. “One group was researching string theory and another researching quantum gravity. These groups hated each other. One stated there were 12 dimensions, the other claimed there were 24. The string theory group believed there couldn’t be 24 dimensions. The quantum gravity group believed that the other scientists were narrow-minded,” explained Khrzhanovskiy.</p></blockquote>
<p>Now available is a part which seems to more centrally involve physics, <a href="https://www.dau.com/en/dau-string-theory">DAU. String Theory</a>, which is described as follows:</p>
<blockquote><p>Nikita Nekrasov is a scientist, a theoretical physicist who studies our world and other possible worlds. He refuses to make a choice between mathematics and physics, between one woman and another, as he ponders the existence of the multi-universe. At scientific conferences, attended by eminent foreign scientists and a rising younger generation of physicists alike, Nekrasov gets carried away debating the beauty of string theory. He attempts to explain to all of his women – Katya, the librarian, Zoya, the scientific secretary, Svetalana, the head of department – about the theory of his own polygamy, and the possibility of having enough feelings to satisfy everyone.</p></blockquote>
<p>Multiple universes have always been advertised with “in some other universe you’re dating Scarlett Johansson”, relating the idea to multiple partners in this universe is an innovation.</p>
<p>I haven’t yet watched DAU. String Theory, will likely find time for that soon. I’m worried that I’ll still not get to see Gross, Yau, Rovelli and others though, and lack the time and energy to look through all the other parts of the film. I’d like to crowd-source a solution to this problem: if anyone watching these things can let the rest of us know in which parts (at what times) well-known math/physics personalities appear, that would be greatly appreciated.</p>Mon, 04 Jan 2021 18:03:56 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110mGejq-l9Z7YTVgI9BJwrBmJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_odpFUr2kc7YK20 Years Later
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/387319311/15156" border=0 width="1" height="1" alt="Story 387319311" title="Story 387319311"> <p>Almost exactly twenty years ago I started writing a short article about the problems with string theory. I had been thinking about doing this for quite a while, and the timing of entering the twenty-first century seemed appropriate for evaluating something that had long been advertised as “a piece of 21st-century physics that had fallen by accident into the 20th”. The piece was done in a week or two, after which I sent it around to a group of physicists to ask for comments. The reaction was mostly positive, although at least one well-known theorist told me that publicly challenging string theorists in this way would be counter-productive.</p>
<p>One person who wrote back was Phil Anderson, I’ve quoted some of what he wrote to me in <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11698">this posting</a>. He suggested I send it to Gloria Lubkin at Physics Today, and evidently talked to her about it. I did do this, and after not hearing anything back for a week or two, decided to go ahead and post the article to the arXiv, where it appeared as <a href="https://arxiv.org/abs/physics/0102051">String Theory: An Evaluation</a>.</p>
<p>Rereading that article today, there’s little I would change. Its argument is even more valid now than then. The problems of the theory and how it was pursued evolved over the next twenty years in ways far worse than what I could have imagined back then. In particular, the “multiverse” argument explaining away why string theory predicts nothing is something I could not have conceived of in 2001. The tribalistic sociology that has led to a large group of people calling themselves “string theorists” when what they do has nothing to do with string theory is also something I would have thought impossible.</p>
<p>In many ways, twenty years of further failure have had less than no effect. Lubos Motl is <a href="https://motls.blogspot.com/2020/12/midsize-miracles-of-perturbative-string.html">still arguing</a> that string theory is the language in which God wrote the universe, and Michio Kaku has a new book about to appear, in which it looks like string field theory is described by <a href="https://www.publishersweekly.com/978-0-385-54274-6">the God Equation</a>. Ignoring these extreme examples, string theory remains remarkably well-entrenched in mainstream physics: for example, my university regularly offers a course training undergraduates in string theory, and prestigious \$3 million prizes are routinely given for work on the subject. The usual mechanisms according to which a failed scientific idea is supposed to fall by the wayside for some reason have not had an effect.</p>
<p>While string theory’s failures have gotten a lot of popular press, the situation is rather different within the physics community. One reason I was interested in publishing the article in Physics Today was that discussion of this issue belongs there, in a place it could get serious attention from within the field. To this day, that has not happened. The story of my article was that I finally did hear back from Lubkin on 2/21/2001. She told me that she would talk to the Physics Today editor Stephen Benka about it. I heard from Benka on 5/6/2001, who told me they wouldn’t publish an article like that, but that I should rework it for publication as a shorter letter to the editor. I did this and sent a short letter version back to them, never heard anything back (a few months later I wrote to ask what had happened to my letter, was told they had decided not to publish it, but didn’t bother to let me know). In 2002 an editor from American Scientist contacted me about the article, and it ended up getting published there.</p>
<p>Looking back at how Physics Today has covered string theory and related speculation over the past 25 years, I did a search and here’s what I found:</p>
<ul>
<li><a href="https://physicstoday.scitation.org/doi/10.1063/1.881493">Reflections on the Fate of Spacetime</a> (Witten) (April 1996)</li>
<li><a href="https://physicstoday.scitation.org/doi/10.1063/1.881680">String Theory Is Testable, Even Supertestable</a> (Kane) (Feb. 1997)</li>
<li><a href="https://physicstoday.scitation.org/doi/abs/10.1063/1.881616">Duality, Spacetime and Quantum Mechanics</a> (Witten) (May 1997)</li>
<li><a href="https://physicstoday.scitation.org/doi/full/10.1063/1.1461326">Large Extra Dimensions: A New Arena for Particle Physics</a> (Arkani-Hamed, Dimopoulos, Dvali) (Feb. 2002)</li>
<li><a href="https://physicstoday.scitation.org/doi/full/10.1063/1.2218556">Is string theory phenomenologically viable?</a>(Gates) (June 2006)</li>
<li><a href="https://physicstoday.scitation.org/doi/10.1063/1.2761818">The case for extra dimensions </a>(Randall) (July 2007)</li>
<li><a href="https://physicstoday.scitation.org/doi/10.1063/1.2825069">String theory in the era of the Large Hadron Collider</a> (Dine) (Dec. 2007)</li>
<li><a href="https://physicstoday.scitation.org/doi/full/10.1063/1.3518211">String theory and the real world</a> (Kane) (Nov. 2010)</li>
<li><a href="https://physicstoday.scitation.org/doi/10.1063/PT.3.2980">What every physicist should know about string theory</a> (Witten) (Nov. 2015)</li>
</ul>
<p>The only thing I could find anywhere during those 25 years indicating to Physics Today readers that none of this speculation had worked out was a short opinion column by Burt Richter</p>
<ul>
<li><a href="https://physicstoday.scitation.org/doi/full/10.1063/1.2387062">Theory in particle physics: Theological speculation versus practical knowledge</a> (Richter) (October 2006)</li>
</ul>
<p>It seems to me that those now in charge of Physics Today should be thinking about this history, their role in it, and what they might be able to do to make up for this heavily one-sided coverage of a controversial issue.</p>Tue, 29 Dec 2020 19:28:44 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110mMF_-sr0WNLzjq7PwYEWiNJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oU9yuPFTVN7QVarious and Sundry
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/380901431/15156" border=0 width="1" height="1" alt="Story 380901431" title="Story 380901431"> <p>A few recent items of interest:</p>
<ul>
<li>Martin Greiter has put together a written version of Sidney Coleman’s mid-1990s lecture <a href="https://arxiv.org/abs/2011.12671">Quantum Mechanics in Your Face</a>, based on a recording of one version of the lecture and copies of Coleman’s slides.
<p>It’s often claimed that leading physicists of Coleman’s generation were educated in and stuck throughout their careers to a “shut up and calculate” approach to the interpretation of quantum mechanics. Coleman’s lecture I believe gives a much better explanation of the way he and many others thought about the topic. In particular, Coleman makes the crucial point:</p>
<blockquote><p> The problem is not the interpretation of quantum mechanics. That’s getting things just backwards. The problem is the interpretation of classical mechanics</p></blockquote>
<p>He ends with the following approach to the measurement problem:</p>
<blockquote><p>Now people say the reduction of the wave packet occurs because it looks like the reduction of the wave packet occurs, and that is indeed true. What I’m asking you in the second main part of this lecture is to consider seriously what it would look like if it were the other way around—if all that ever happened was causal evolution according to quantum mechanics. What I have tried to convince you is that what it looks like is ordinary everyday life.</p></blockquote>
<p>While some might take this and claim Coleman as an Everettian, note that there’s zero mention anywhere of many-worlds. Likely he found that an empty idea that explains nothing, so not worth mentioning.</li>
<li>For the past year the CMSA has been hosting a <a href="https://cmsa.fas.harvard.edu/literature-lecture-series/">Math-Science Literature Lecture Series</a>. The talks have typically been excellent surveys of areas of mathematics, given by leading figures in each field. To coordinate with Tsinghua, the talks have often been at 8am here in NYC, and several times the last couple months I’ve made sure to get up early enough to have breakfast while watching one of the talks. All of the ones I’ve seen were very much worth the time, they were the ones given by Edward Witten, Andrei Okounkov, Alain Connes, Arthur Jaffe and Nigel Hitchin. Jaffe’s covered some of the ideas on Euclidean field theory that I’ve been spending a lot of time thinking about. For a more detailed version of his talk I highly recommend <a href="https://www.arthurjaffe.net/Assets/pdf/Quantum-Theory_Relativity.pdf">this article</a>.</li>
<li>Peter Scholze has posted at the Xena blog <a href="https://xenaproject.wordpress.com/2020/12/05/liquid-tensor-experiment/">a challenge</a> to those interested in formalizing mathematics and automated theorem proving (or checking): formalize and check the proof of a foundational result in his work with Dustin Clausen on “condensed mathematics”. As part of the challenge, he provides an extensive discussion of the motivation and basic ideas of this subject, which attempts to provide a replacement (with better properties) for the conventional definition of a topological space.
<p>Spending a little time reading this and some of the other expositions of the subject convinced me this is a really thorny business. Scholze explains in detail his motivation for making the challenge in part 6 of the posting. My suspicion has always been that most of the value of computer theorem checking lies in forcing a human to lay out clearly and unambiguously the details of an argument, with that effort likely to make clear if there’s a problem with the theorem. It will be fascinating to see what comes of this project.</p>
<p>I see there’s also a <a href="https://golem.ph.utexas.edu/category/2020/12/the_liquid_tensor_experiment.html">blog posting about this at the n-category cafe</a>.
</li>
<li>On the topic of <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11723">theorems that definitely don’t have a clear and unambiguous proof</a>, supposedly <a href="https://ems.press/updates/2020-11-16-prims-special-issues-2021">PRIMS will be publishing Mochizuki’s IUT papers</a> in 2021. Mochizuki and collaborators have a <a href="http://www.kurims.kyoto-u.ac.jp/~motizuki/Explicit%20estimates%20in%20IUTeich.pdf">new paper claiming stronger versions of Mochizuki’s results</a>. </li>
</ul>Sun, 06 Dec 2020 20:56:06 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110mCP1mXMhpUEjjq7PwYEWiNJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oc-EEjvZB8hVContemplating the End of Physics
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/377609719/15156" border=0 width="1" height="1" alt="Story 377609719" title="Story 377609719"> <p>In a remarkable article entitled <a href="https://www.quantamagazine.org/the-end-of-physics-20201124">Contemplating the End of Physics</a> posted today at Quanta magazine, Robbert Dijkgraaf (the director of the IAS) more or less announces the arrival of the scenario that John Horgan <a href="https://www.amazon.com/End-Science-Knowledge-Twilight-Scientific/dp/0201626799">predicted for physics back in 1996</a>. Horgan argued that physics was reaching the end of its ability to progress by finding new fundamental laws. Research trying to find new fundamental constituents of the universe and new laws governing them was destined to reach an endpoint where no more progress was possible. This is pretty much how Dijkgraaf now sees the field going forward:</p>
<blockquote><p>Confronted with the endless number of physical systems we could fabricate out of the currently known fundamental pieces of the universe, I begin to imagine an upside-down view of physics. Instead of studying a natural phenomenon, and subsequently discovering a law of nature, one could first design a new law and then reverse engineer a system that actually displays the phenomena described by the law. For example, physics has moved far beyond the simple phases of matter of high school courses — solid, liquid, gas. Many potential “exotic” phases, made possible by the bizarre consequences of quantum mechanics, have been cataloged in theoretical explorations, and we can now start realizing these possibilities in the lab with specially designed materials.</p>
<p>All of this is part of a much larger shift in the very scope of science, from studying what is to what could be. In the 20th century, scientists sought out the building blocks of reality: the molecules, atoms and elementary particles out of which all matter is made; the cells, proteins and genes that make life possible; the bits, algorithms and networks that form the foundation of information and intelligence, both human and artificial. This century, instead, we will begin to explore all there is to be made with these building blocks.</p></blockquote>
<p>In brief, as far as physics goes, elementary particle physics is over, from now on it’s pretty much just going to be condensed matter physics, where there at least is an infinity of potential effective field theory models to play with.</p>
<p>Dijkgraaf ends with an argument indicating that human intelligence is outmoded, artificial intelligence is our future:</p>
<blockquote><p>Science concerns all phenomena, including the ones created in our laboratories and in our heads. Once we are fully aware of this grander scope, a different image of the research enterprise emerges. Now, finally, the ship of science is leaving the safe inland waterways carved by nature, and is heading for the open ocean, exploring a brave new world with “artificial” materials, organisms, brains and perhaps even a better version of ourselves.</p></blockquote>
<p>Along the same lines, today also brings an article in the New York Times by Dennis Overbye, <a href="https://www.nytimes.com/2020/11/23/science/artificial-intelligence-ai-physics-theory.html">Can a Computer Devise a Theory of Everything?</a> The article discusses the new <a href="https://iaifi.org">MIT Institute for Artificial Intelligence and Fundamental Interactions</a> and Max Tegmark’s hopes that AI will “discover all kinds of new laws of physics”. My guess is that this will work just fine if you give up on the 20th century understanding of what a “law of physics” is and follow Dijkgraaf’s lead. The problem then may be not so much “will we understand the new laws of physics found by AI?”, but rather that of them not being interesting enough to be worth understanding… </p>Tue, 24 Nov 2020 23:55:44 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110k3J6mqWxQh7n1z8-xSOmNlJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oQOBIWB5Pd3xVarious Links, String Theory now Untethered
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/374310034/15156" border=0 width="1" height="1" alt="Story 374310034" title="Story 374310034"> <p>I’ve been spending most of my time recently trying to get unconfused about Euclidean spinor fields, will likely write something here about that in the not too distant future. Some other things that may be of interest:</p>
<ul>
<li>I did <a href="https://www.youtube.com/watch?v=OlfLmaeHHJU">an interview</a> a couple days ago with Fraser Cain, who runs the <a href="https://www.universetoday.com/">Universe Today</a> website. He had some excellent and well-informed questions about the state of HEP physics. I regret a little bit that I focused on giving an even-handed explanation of the arguments over a next generation collider, didn’t emphasize that personally I think building such a thing is a good idea (if the money can somehow be found), since the alternative would be giving up and abandoning this kind of fundamental science.</li>
<li>On Monday, the Simons Center celebrated its 10th birthday, talks are<a href="http://scgp.stonybrook.edu/video/results.php?event_id=338"> here</a>, giving a good overview of the kinds of math and physics that have been going on there during its first decade.</li>
<li>For the latest on the formulation of the local Langlands correspondence in terms of the geometry of the Fargues-Fontaine curve, Peter Scholze is teaching a course now in Bonn, website <a href="http://www.math.uni-bonn.de/people/scholze/Geometrization/">here</a>.</li>
<li>Kirill Krasnov has a book out from Cambridge, <a href="https://www.cambridge.org/core/books/formulations-of-general-relativity/1C561017F604EB7259025CB2BB8BA5BA">Formulations of General Relativity</a>. If you share my current interest in chiral formulations of GR and twistors, there’s a lot about these in the book. For a more general interest survey of what’s in the book, see Krasnov’s lectures last year at Perimeter (links and slides are on <a href="https://www.maths.nottingham.ac.uk/plp/pmzkk/">his website</a>).</li>
<li>A couple weeks ago, a very well-done <a href="https://www.quantamagazine.org/the-black-hole-information-paradox-comes-to-an-end-20201029">explanation of what’s been going on around the black hole information paradox</a> written by George Musser appeared at Quanta Magazine. Periodically in recent years I’ve tried to follow what’s up with this subject, generally giving up after a while, frustrated especially at not being able to figure out what underlying theory of quantum gravity was being studied. All that ever was clear was that this was about low-dimensional toy model calculations involving some assumptions that had ingredients coming from holography and AdS/CFT.
<p>Musser’s article makes quite a few things clearer, with one striking aspect the news that:</p>
<blockquote><p>researchers cut the tether to string theory altogether.</p></blockquote>
<p>which I gather means that any foundation in AdS/CFT is gone, with what is being discussed now purely semi-classical. I don’t understand what these new semi-classical calculations are, and whether optimistic claims that the information paradox is on its way to a solution are justified (history hasn’t been kind to previous such claims). In recent years the pro-string theory research argument has often been that while there no longer were any prospects that it would tell us about particle physics, it was the best route to solving the problem of quantum gravity. It will be interesting to see what the effect will be of that cord getting cut by leading researchers. </p>
<p>If you think it’s a good idea to follow discussions of this kind of thing on Twitter, you might enjoy threads from <a href="https://twitter.com/skdh/status/1322077199667765248">Sabine Hossenfelder</a> and <a href="https://twitter.com/AlmheiriAE/status/1323290329794170880">Ahmed Almeiri</a>.
</li>
</ul>Fri, 13 Nov 2020 16:31:59 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110lszvNa8nleRanAxiD9qXc5Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oUCny7rSS2V-Do Particle Physicists Continue to Make Empty Promises?
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/367985519/15156" border=0 width="1" height="1" alt="Story 367985519" title="Story 367985519"> <p>Blogging has been light here, since little worthy of note in math/physics has been happening, and I’ve been busy with teaching, freaking out about the election, and trying to better understand Euclidean spinors. I’ll write soon about the Euclidean spinors, but couldn’t resist today making some comments about two things I’ve seen this week.</p>
<p>Sabine Hossenfelder yesterday had a blog entry/Youtube video entitled <a href="http://backreaction.blogspot.com/2020/10/particle-physicists-continue-to-make.html">Particle Physicists Continue to Make Empty Promises</a>, which properly takes exception to this quote:</p>
<blockquote><p>A good example of a guaranteed result is dark matter. A proton collider operating at energies around 100 TeV will conclusively probe the existence of weakly interacting dark-matter particles of thermal origin. This will lead either to a sensational discovery or to an experimental exclusion that will profoundly influence both particle physics and astrophysics. </p></blockquote>
<p>from a <a href="https://www.nature.com/articles/s41567-020-01054-6">recent article</a> by Fabiola Gianotti and Gian Francesco Giudice in <em>Nature Physics</em>. She correctly notes that</p>
<blockquote><p>They guarantee to rule out some very specific hypotheses for dark matter that we have no reason to think are correct in the first place.</p></blockquote>
<p>A 100 TeV collider can rule out certain kinds of higher-mass WIMPs, but it’s simply untrue that such an exclusion will “profoundly influence both particle physics and astrophysics.” Very few people think such a thing is likely since there’s no evidence for it and no well-motivated theory that predicts it.</p>
<p>Where I part company with Hossenfelder though is that I don’t see much wrong with the rest of the Gianotti/Giudice piece and don’t agree with her point of view that the big problem here is empty promises like this and plans for a new collider. Twenty years ago when I began writing N<em>ot Even Wrong</em>, I started out by writing a chapter about the inherent physical limits that colliders were starting to hit, and the significance of this for the field. It was already clear that getting to higher proton energies than the LHC, or higher lepton energies than LEP was going to be very difficult and expensive. HEP experimentalists are now facing painful and hard choices about the future, which I wrote about in detail here under the title <a href="https://www.math.columbia.edu/~woit/wordpress/?p=10768">Should the Europeans Give Up?</a>. The worldwide experimental HEP community is addressing the problem in a serious way, with the European Strategy Update one aspect, and the US now engaged in a similar <a href="https://snowmass21.org/">Snowmass 2021</a> effort.</p>
<p>Many find it tempting to believe that the answer is simple: just redirect funds from collider physics to non-collider experiments. The problem is that there’s little evidence of promising but unfunded ideas for non-collider experiments. For the last decade there has been no new construction of high energy colliders, with as much money as ever available worldwide for HEP experiments. This should have been a golden age for those with non-collider ideas to propose. This continues to be the case: if you look at the European Strategy Update and Snowmass 2021 efforts, they have seriously focused on finding non-collider ideas to pursue. This should continue to be true, since I see no evidence anyone is going to decide to go ahead with a next generation collider and start spending money building it during the next few years. The bottom line result from the European process was not a decision to build a new collider, but a decision to keep studying the problem, then evaluate what to do in 2026. For the ongoing American process, as far as I know a new US collider is not even a possibility being discussed.</p>
<p>While HEP experiment is facing difficult times because of fundamental physical, engineering and economic limits, the problems of HEP theory are mostly self-inflicted. The decision nearly 40 years ago by a large fraction of the field to orient their research programs around bad ideas that don’t work (SUSY extensions of the Standard Model and string theory unification), then spend decades refusing to acknowledge failure is at the core of the sad state of the subject these days.</p>
<p>About the canniest and most influential HEP theorist around is Nima Arkani-Hamed, and a few days ago I watched an <a href="https://www.facebook.com/imaginescience/videos/the-world-of-thinking-a-conversation-between-nima-arkani-hamed-janna-levin/353045532687868/">interview of him by Janna Levin</a>. On the question of the justification for a new collider, he’s careful to state that the justification is mainly the study of the Higgs. He’s well aware that the failure of the “naturalness” arguments for weak-scale SUSY needs to be acknowledged and does so. He also is well aware that any attempt to argue this failure away by saying “we just need a higher energy collider” won’t pass the laugh test (and would bring Hossenfelder and others down on him like a ton of bricks…).</p>
<p>The most disturbing aspect of the interview is that Levin devotes a lot of time (and computer graphics) to getting Arkani-Hamed to explain his 1998 ideas about “large extra dimensions”, repeatedly telling the audience that he has been given a \$3 million prize for them. <a href="https://arxiv.org/abs/hep-ph/9803315">This paper</a> has by now been cited over 6300 times, and the multi-million dollar business is correct, with the prize citation explaining:</p>
<blockquote><p>Nima Arkani-Hamed has proposed a number of possible approaches to this [<em>hierarchy problem</em>] paradox, from the theory of large extra dimensions, where the strength of gravity is diluted by leaking into higher dimensions, to “split supersymmetry,” motivated by the possibility of an enormous diversity of long-distance solutions to string theory.</p></blockquote>
<p>At the time it was pretty strange that a \$3 million dollar prize was being given for ideas that weren’t working out. It’s truly bizarre though that Levin would now want to make such failed ideas the centerpiece of a presentation to the public, misleading people about their status. The website for the interview also promotes Arkani-Hamed purely in terms of his failures, presented as successes:</p>
<blockquote><p>Nima Arkani-Hamed is one of the leading particle physics phenomenologists of the generation. He is concerned with the relation between theory and experiment. His research has shown how the extreme weakness of gravity, relative to other forces of nature, might be explained by the existence of extra dimensions of space, and how the structure of comparatively low-energy physics is constrained within the context of string theory. He has taken a lead in proposing new physical theories that can be tested at the Large Hadron Collider at CERN in Switzerland,</p></blockquote>
<p>This is part of the overall weird situation of the failed ideas (SUSY/strings) of 40 years ago: they still live on in a dominant position when the subject is presented to the public.</p>
<p>At the same time, the topics Arkani-Hamed is working on now are ones I think are more promising than most of the rest of what is going on in HEP theory. The interview began with a discussion of <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11899">Penrose’s recent Nobel Prize</a>, with Arkani-Hamed explaining Penrose’s fantastic insights about twistor geometry and noting that his own current work involves a fundamental role for twistor space (personally I see some <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11899">other promising directions for using twistor geometry</a>, more to come about this here in the future).</p>
<p>In contrast to Hossenfelder, what I’m seeing these days in HEP physics is not a lot of empty promises (which were a dominant aspect of HEP theory for several decades). Instead, on the experimental side, there’s an honest struggle with implacable difficulties. On the theory side increasingly people have just given up, deciding that it’s better to let the subject die chained to a host of \$3 million prizes for dead ideas than to honestly face up to what has happened.</p>Fri, 23 Oct 2020 23:38:18 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110n441Qvt5f9pn1z8-xSOmNlJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_ofqkgQuZw1yO2020 Physics Nobel Prize
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/362560915/15156" border=0 width="1" height="1" alt="Story 362560915" title="Story 362560915"> <p>The 2020 Physics Nobel Prize was <a href="https://www.nobelprize.org/prizes/physics/2020/summary/">announced this morning</a>, with half going to Roger Penrose for his work on black holes, half to two astronomers (Reinhard Genzel and Andrea Ghez) for their work mapping what is going on at the center of our galaxy. I know just about nothing about the astronomy side of this, but am somewhat familiar with Penrose’s work, which very much deserves the prize.</p>
<p>Penrose is a rather unusual choice for a Physics Nobel Prize, in that he’s very much a mathematical physicist, with a Ph.D. in mathematics (are there other physics winners with math Ph.Ds?). In addition, the award is not for a new physical theory, or for anything experimentally testable, but for the rigorous understanding of the implications of Einstein’s general relativity. While I’m a great fan of the importance of this kind of work, I can’t think of many examples of it getting rewarded by the Nobel prize. I had always thought that Penrose was likely to get a Breakthrough Prize rather than a Nobel Prize, still don’t understand why that hasn’t happened already.</p>
<p>Besides the early work on black holes that Penrose is being recognized for, he has worked on many other things which I think are likely to ultimately be of even greater significance. In particular, he’s far and away the person most responsible for twistor theory, a subject which I believe has a great future ahead of it at the core of fundamental physical theory.</p>
<p>In all his work, Penrose has shown a remarkable degree of originality and creativity. He’s not someone who works to make an advance on ideas pioneered by others, but sets out to do something new and different. His book “The Road to Reality” is a masterpiece, an inspiring original and deep vision of the unity of geometry and physics that outshines the mainstream ways of looking at these questions. </p>
<p>Congratulations to Sir Roger, and compliments to the Nobel prize committee for a wonderful choice!</p>Tue, 06 Oct 2020 15:33:05 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110k7gw0CArcfM06NAX1_5kxdJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_odyE4RFDiep5Quick Links
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/354571105/15156" border=0 width="1" height="1" alt="Story 354571105" title="Story 354571105"> <p>A few quick links:</p>
<ul>
<li>I was sorry to hear of the recent death of Vaughan Jones. A few things about his life and work have started to appear, see <a href="https://terrytao.wordpress.com/2020/09/09/vaughan-jones/">here</a>, <a href="https://news.vanderbilt.edu/2020/09/09/vaughan-jones-preeminent-vanderbilt-mathematician-has-died/">here</a> and <a href="https://www.ams.org/news?news_id=6374">here</a>.</li>
<li>For a wonderful in-depth article about the life of Michael Atiyah written by Nigel Hitchin, see <a href="https://royalsocietypublishing.org/doi/10.1098/rsbm.2020.0001">here</a>.</li>
<li>There are now many new places where you can find talks about math and physics to listen to. For instance, just for math and just at Harvard, there is a series of <a href="https://cmsa.fas.harvard.edu/literature-lecture-series/">Harvard Math Literature</a> talks and Dennis Gaitsgory’s <a href="http://people.math.harvard.edu/~gaitsgde/GLOH_2020/">geometric Langlands office hours</a>.</li>
<li>Breakthrough Prizes were announced today. There’s an argument to be made that the best policy is to ignore them. Weinberg has another 3 million dollars.</li>
<li>For an interview with Avi Loeb about why physics is stuck, see <a href="https://www.salon.com/2020/09/06/physics-is-stuck--and-needs-another-einstein-to-revolutionize-it-physicist-avi-loeb-says/">here</a>.</li>
<li>For an explanation from John Preskill of why quantum computing is hard (which I’d claim has to do with why the measurement problem is hard), see <a href="https://www.amazon.science/blog/amazon-scholar-john-preskill-on-the-aws-quantum-computing-effort">here</a>.</li>
</ul>Thu, 10 Sep 2020 18:38:16 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110kSDw_QL1bxD06NAX1_5kxdJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oRZkU_kFzNeNFall Quantum Mechanics Class
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/353572463/15156" border=0 width="1" height="1" alt="Story 353572463" title="Story 353572463"> <p>I’ll be teaching a course on quantum mechanics this year here at Columbia, from a point of view aimed somewhat at mathematicians, emphasizing the role of Lie groups and their representations. For more details, the course webpage is <a href="http://www.math.columbia.edu/%7Ewoit/QM/fall2020.html">here</a>.</p>
<p>The course is being taught online using Zoom, with 37 students now enrolled. I’ve set things up in my office to try and teach using the blackboard there, and will be interacting with the students mostly via Zoom. As an experiment, I’ve also set up a <a href="https://www.youtube.com/channel/UCdSEKN94Jo1xjUHVyfEfIjg">Youtube channel</a>. If all goes well you should be able to find a livestream of the class there while it’s happening, which is scheduled for 4:10-5:25 Tuesdays and Thursdays, starting tomorrow, September 8. I’ll also try and make sure the recorded livestreams get uploaded and saved at <a href="https://www.youtube.com/playlist?list=PLOaEOh8qMwDLoBJinaH3p31edODHdlb93">this playlist</a>. Unfortunately I won’t be able to interact with people watching on Youtube, should have my hands full trying to get to know the students enrolled here in the course, with only this virtual connection.</p>Mon, 07 Sep 2020 21:56:11 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110lxa1Uf08r2L7V8HZmzB6MmJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oag5YTd7ezhjAMS Open Math Notes
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/353278702/15156" border=0 width="1" height="1" alt="Story 353278702" title="Story 353278702"> <p>The AMS for the last few years has had a valuable project called <a href="https://www.ams.org/open-math-notes">AMS Open Math Notes</a>, a site to gather and make available course notes for math classes, documents of the sort that people sometimes make available on their websites. This provides a great place to go to look for worthwhile notes of this kind (many of them are of very high quality), as well as ensuring their availability for the future. They have an advisory board that evaluates whether submitted notes are suitable.</p>
<p>A couple months ago I submitted the <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11683">course notes I wrote up this past semester for my Fourier Analysis class</a>, and I’m pleased that they were accepted and are now available <a href="https://www.ams.org/open-math-notes/omn-view-listing?listingId=110834">here at the AMS site</a> (and will remain also available <a href="https://www.math.columbia.edu/~woit/fourier-analysis/fouriernotes.pdf">from my website</a>).</p>Sun, 06 Sep 2020 17:42:54 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110mM_Vk22x2P5KpSGW1eS8dIJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_ob_lFWndvTytQuantum Reality
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/352153380/15156" border=0 width="1" height="1" alt="Story 352153380" title="Story 352153380"> <p>Jim Baggott’s new book, <a href="https://global.oup.com/academic/product/quantum-reality-9780198830153">Quantum Reality</a>, is now out here in US, and I highly recommend it to anyone interested in the issues surrounding the interpretation of quantum mechanics. Starting next week I’ll be teaching a course on quantum mechanics for mathematicians (more about this in a few days when I have a better idea how it’s going to work). I’ll be lecturing about the formalism, and for the topic of how this connects to physical reality I’ll be referring the students to this new book (as well as Philip Ball’s <a href="https://www.math.columbia.edu/~woit/wordpress/?p=10522">Beyond Weird</a>).</p>
<p>When I was first studying quantum mechanics in the early-mid 1970s, the main popular sources discussing interpretational issues were uniform triumphalist accounts of how physicists had struggled with these issues and finally ended up with the “Copenhagen interpretation” (which no one was sure exactly how to state, due to diversity of opinion among theorists and Bohr’s obscurity of expression). Everyone now says that the reigning ideology of the time was “shut up and calculate”, but that’s not exactly what I remember. The Standard Model had just appeared, offering up a huge advance and a long list of new questions with powerful methods to attack them. In this context it was was hard to justify spending time worrying about the subtleties of what Copenhagen might have gotten wrong.</p>
<p>In recent decades things have changed completely, with the question of what’s wrong with Copenhagen and how to do better getting a lot of attention. By now a huge and baffling literature about alternatives has accumulated, forming somewhat of a tower of Babel confronting anyone trying to learn more about the subject. Some popular accounts have dealt with this complexity by turning the subject into a morality play, with alternative interpretations portrayed as the Rebel Alliance fighting righteous battles against the Copenhagen Empire. Others accounts are pretty much propaganda for a particular alternative, be it Bohmian mechanics or a many-worlds interpretation.</p>
<p>Instead of something like this, Baggott provides a refreshingly sane and sensible survey of the subject, trying to get at the core of what is unsatisfying about the Copenhagen account, while explaining the high points of the many different alternatives that have been pursued. He doesn’t have an ax to grind, sees the subject more as a “Game of Theories” in which one must navigate carefully, avoiding Scylla, Charybdis, and various calls from the Sirens. One thing which is driving this whole subject is the advent of new technologies that allow the experimental study of quantum coherence and decoherence, with great attention being paid as possible quantum computing technology has become the hottest and best-funded topic around. Whatever you think about Copenhagen, what Bohr and others characterized as inaccessible to experiment is now anything but that.</p>
<p>While one of my least favorite aspects of discussions of this subject is the various ways the terms “real” and “reality” get used, I have realized that one has to get over that when trying to follow people’s arguments, since the terms have become standard sign-posts. What’s at issue here are fundamental questions about physical science and reality, including the question of what the words “real” and “reality” might mean. In <em>Quantum Reality</em>, Baggott provides a well-informed, reliable and enlightening tour of the increasingly complex and contentious terrain of arguments over what our best fundamental theory is telling us about what is physically “real”.</p>Wed, 02 Sep 2020 23:01:25 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110ktww8LCVc_iXawZ12B-dU6Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oa7wGc8VMmn_Funding Priorities
https://api.follow.it/track-rss-story-click/AaY2ldA110l9bCbN46A9TqnAxiD9qXc5Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oeX8lipPLhBx
<img src="https://api.follow.it/rssubscribers/rss_show_story_count/349927374/15156" border=0 width="1" height="1" alt="Story 349927374" title="Story 349927374"> <p>The research that gets done in any field of science is heavily influenced by the priorities set by those who fund the research. For science in the US in general, and the field of theoretical physics in particular, recent years have seen a reordering of priorities that is becoming ever more pronounced. As a prominent example, recently <a href="https://www.nature.com/articles/d41586-020-02272-x">the NSF announced</a> that their graduate student fellowships (a program that funds a large number of graduate students in all areas of science and mathematics) will now be governed by the following language:</p>
<blockquote><p>Although NSF will continue to fund outstanding Graduate Research Fellowships in all areas of science and engineering supported by NSF, in FY2021, GRFP will emphasize three high priority research areas in alignment with NSF goals. These areas are Artificial Intelligence, Quantum Information Science, and Computationally Intensive Research. Applications are encouraged in all disciplines supported by NSF that incorporate these high priority research areas.</p></blockquote>
<p>No one seems to know exactly what this means in practice, but it clearly means that if you want the best chance of getting a good start on a career in science, you really should be going into one of</p>
<ul>
<li>Artificial Intelligence</li>
<li>Quantum Information Science</li>
<li>Computationally Intensive Research</li>
</ul>
<p>or, even better, trying to work on some intersection of these topics.</p>
<p>Emphasis on these areas is not new; it has been growing significantly in recent years, but this policy change by the NSF should accelerate ongoing changes. As far as fundamental theoretical physics goes, we’ve already seen that the move to quantum information science has had a significant effect. For example, the IAS PiTP summer program that trains students in the latest hot topics in 2018 was devoted to <a href="https://static.ias.edu/pitp/2018/index.html">From Qubits to Spacetime</a>. The impact of this change in funding priorities is increased by the fact that the largest source of private funding for theoretical physics research, the Simons Foundation, share much the same emphasis. The new Simons-funded Flatiron Institute here in New York has as mission statement</p>
<blockquote><p>The mission of the Flatiron Institute is to advance scientific research through computational methods, including data analysis, theory, modeling and simulation. </p></blockquote>
<p>In the latest development on this front, the White House <a href="https://www.energy.gov/articles/white-house-office-technology-policy-national-science-foundation-and-department-energy">announced today</a> \$1 billion in funding for artificial intelligence and quantum information science research institutes: </p>
<blockquote><p>“Thanks to the leadership of President Trump, the United States is accomplishing yet another milestone in our efforts to strengthen research in AI and quantum. We are proud to announce that over $1 billion in funding will be geared towards that research, a defining achievement as we continue to shape and prepare this great Nation for excellence in the industries of the future,” said Advisor to the President Ivanka Trump.</p></blockquote>
<p>This includes <a href="https://www.nsf.gov/news/special_reports/announcements/082620.jsp">an NSF component</a> of \$100 million dollars in new funding for five Artificial Intelligence research institutes. One of these will largely be a fundamental theoretical physics institute, to be called the <a href="https://iaifi.org/">NSF AI Institute for Artificial Intelligence and Fundamental Interactions (IAIFI)</a>. The theory topics the institute will concentrate on will be</p>
<ul>
<li>Accelerating Lattice Field Theory with AI</li>
<li>Exploring the Multiverse with AI</li>
<li>Classifying Knots with AI</li>
<li>Astrophysical Simulations with AI</li>
<li>Towards an AI Physicist</li>
<li>String Theory Conjectures via AI</li>
</ul>
<p>As far as trying to get beyond the Standard Model, the IAIFI plan is to </p>
<blockquote><p>work to understand physics beyond the SM in the frameworks of string and knot theory.</p></blockquote>
<p>I’m rather mystified by how knot theory is going to give us beyond the SM physics, perhaps the plan is to revive <a href="https://en.wikipedia.org/wiki/Vortex_theory_of_the_atom">Lord Kelvin’s vortex theory</a>.</p>Wed, 26 Aug 2020 15:54:25 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110l9bCbN46A9TqnAxiD9qXc5Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oeX8lipPLhBxStraight Old White Guys and Their Theories of Everything
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/348592021/15156" border=0 width="1" height="1" alt="Story 348592021" title="Story 348592021"> <p>I’m a big fan of Sabine Hossenfelder’s music videos, the latest of which, <a href="https://www.youtube.com/watch?v=5gmtAeqRs14">Theories of Everything</a>, has recently appeared. I also agree with much of the discussion of this <a href="http://backreaction.blogspot.com/2020/08/theories-of-everything-ive-been-singing.html">at her latest blog posting</a> where Steven Evans writes</p>
<blockquote><p>nobody wants to see Peter Woit sing.</p></blockquote>
<p>and Terry Bollinger chimes in:</p>
<blockquote><p>Please, under no circumstances and in no situations, should folks like Peter Woit, Lee Smolin, Garrett Lisi, Sean Carroll, or even John Baez try to spice up their blogs or tweets by adding clips of themselves singing self-composed physics songs.</p>
<p>Trust me, fellow males of the species: However tempted you may be by Sabine’s spectacular success in this arena, it just ain’t gonna work for you!</p></blockquote>
<p>The chorus of Sabine’s song goes:</p>
<blockquote><p>
All you guys with theories of everything<br />
Who follow me wherever I am traveling<br />
Your theories are neat<br />
I hope they will succeed<br />
But please, don’t send them to me
</p></blockquote>
<p>One reason for her bursting into song like this was probably her recent participation in <a href="http://imagination.ucsd.edu/_wp/podcast/theories-of-everything-cosmic-controversies-great-debates-and-scientific-speculations-part-2/">this discussion</a>. I’d like to think (for no good reason) that it had nothing to do with my recently sending her a copy of <a href="http://www.math.columbia.edu/~woit/twistors.pdf">this</a>.</p>
<p>Today brought a <a href="https://www.youtube.com/watch?v=GfRJZbsywPQ">new discussion of theories of everything</a>, by Brian Greene and Cumrun Vafa. When asked by Greene to give a grade to string theory, Vafa said that he would give it a grade of A+, although its grade was less than A on the experimental verification front.</p>
<p>Over the years I’ve been sent more than my fair share of theories of everything, and Sabine is right that they all come from men. In addition, all available evidence is that these men are typically old, straight and white. As someone who <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11899">recently decided he may have an idea about a theory of everything</a>, it has not escaped my attention that pretty much all of these things are nonsense and their authors are, besides being old, straight, white and male, suffering from various degrees of self-delusion.</p>
<p>So, while I’m enthusiastic about new ideas involving twistors and happily continuing to work on them, it’s pretty clear that this is not a good time to be bringing them to market. The elite academic world of Harvard and Princeton theorists that I was trained in has been doing an excellent job of convincing everyone that even the smartest people in the world could not make any progress towards a TOE, and that all claims for such progress from the most respected experts around are not very credible. Best to ignore not just the cranks who fill up your inbox with such claims, but all of them, judging the whole concept to be doomed until the point in the far distant future when an experiment finally provides the clue to the correct way forward. </p>
<p>Given current active social debates, that these kinds of claims are coming from the most unenlightened of all sources (straight old white guys) doesn’t help with trying to get positive attention. Somewhat correlated with the straight old white guy thing though, I’m in a pretty privileged position of being able to keep happily working on what I want to work on, no matter what its market value.</p>
<p>Be warned though, if people don’t pay some more attention, I’m going to start writing songs and singing them here.</p>Fri, 21 Aug 2020 20:16:10 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110lpgrynIGAsczjq7PwYEWiNJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oZ0NBDkVuORrTwistors and the Standard Model
https://api.follow.it/track-rss-story-click/AaY2ldA110k50lVpcY5P331z8-xSOmNlJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oeMJ0nZwBmzx
<img src="https://api.follow.it/rssubscribers/rss_show_story_count/345387299/15156" border=0 width="1" height="1" alt="Story 345387299" title="Story 345387299"> <p>For the past few months I’ve been working on writing up some ideas I’m quite excited about, and the pandemic has helped move things along by removing distractions and forcing me to mostly stay home. There’s now something written that I’d like to publicize, a draft manuscript entitled <a href="https://www.math.columbia.edu/~woit/twistors.pdf">Twistor Geometry and the Standard Model in Euclidean Space</a>, which at some point soon I’ll put on the arXiv. My long experience with both hype about unification in physics as well as theorist’s huge capacity for self-delusion on the topic of their own ideas makes me wary, but I’m very optimistic that these ideas are a significant step forward on the unification front. I believe they provide a remarkable possibility for how internal and space-time symmetries become integrated at short distances, without the usual problem of introducing a host of new degrees of freedom.</p>
<p>Twistor theory has a long history going back to the 1960s, and it is such a beautiful idea that there always has been a good argument that there is something very right about it. But it never seemed to have any obvious connection to the Standard Model and its pattern of internal symmetries. The main idea I’m writing about is that one can get such a connection, as long as one looks at what is happening not just in Minkowski space, but also in Euclidean space. One of the wonderful things about twistor theory is that it includes both Minkowski and Euclidean space as real slices of a complex, holomorphic, geometry. The points in these spaces are best understood as complex lines in another space, projective twistor space. It is on projective twistor space that the internal symmetries of the Standard Model become visible.</p>
<p>The draft paper contains the details, but I should make clear what some of the arguments are for taking this seriously:</p>
<ul>
<li>Unlike other ideas about unification out there, it’s beautiful. The failure of string theory unification has caused a backlash against the idea of using beauty as a criterion for judging unification proposals. I won’t repeat here my usual rant about this. As an example of what I mean about “beauty”, the fundamental spinor degree of freedom appears here tautologically: a point is by definition exactly the $\mathbf C^2$ spinor degree of freedom at that point.</li>
<li>Conformal invariance is built-in. The simplest and most highly symmetric possibility for what fundamental physics does at short distances is that it’s conformally invariant. In twistor geometry, conformal invariance is a basic property, realized in a simple way, by the linear $SL(4,\mathbf C)$ group action on the twistor space $\mathbf C^4$. This is a complex group action with real forms $SU(2,2)$ (Minkowski) and $SL(2,\mathbf H)$ (Euclidean).</li>
<li>The electroweak $SU(2)$ is inherently chiral. For many other ideas about unification, it’s hard to get chiral interactions. In twistor theory one problem has always been the inherent chiral nature of the theory. Here this becomes not a problem but a solution.</li>
</ul>
<p>At the same time I should also make clear that what I’m describing here is very incomplete. Two of the main problems are:</p>
<ul>
<li>The degrees of freedom naturally live not on space-time but on projective twistor space $PT$, with space-time points complex projective lines in $PT$. Standard quantum field theory with fields parametrized by space-time points doesn’t apply and how to work instead on $PT$ is unclear. There has been some work on formulating QFT on $PT$ as a holomorphic Chern-Simons theory, and perhaps that work can be applied here.</li>
<li>There is no idea for where generations come from. Instead of $PT$ perhaps the theory should be formulated on $S^7$ (space of unit length twistors) and other aspects of the geometry there exploited. In some sense, the incarnations of twistors as four complex number or two quaternions are getting used, but maybe the octonions are relevant.</li>
</ul>
<p>What I think is probably most important here is that this picture gives a new and compelling idea about how internal and space-time symmetries are related. The conventional argument has always been that the Coleman-Mandula no-go theorem says you can’t combine internal and space-time symmetries in a non-trivial way. Coleman-Mandula does not seem to apply here: these symmetries live on $PT$, not space-time. To really show that this is all consistent, one needs a full theory formulated on $PT$, but I don’t see a Coleman-Mandula argument that a non-trivial such thing can’t exist.</p>
<p>What is most bizarre about this proposal is the way in which, by going to Euclidean space-time, you change what is a space-time and what is an internal symmetry. The argument (see <a href="https://www.math.columbia.edu/~woit/wordpress/?p=11865">a recent posting</a>) is that, formulated in Euclidean space, the 4d Euclidean symmetry is broken to 3d Euclidean symmetry by the very definition of the theory’s state space, and one of the 4d $SU(2)$s give an internal symmetry, not just analytic continuation of the Minkowski boost symmetry. There is still a lot about how this works I don’t understand, but I don’t see anything inconsistent, i.e. any obstruction to things working out this way. If the identification of the direction of the Higgs field with a choice of imaginary time direction makes sense, perhaps a full theory will give Higgs physics in some way observably different from the usual Standard Model.</p>
<p>One thing not discussed in this paper is gravity. Twistor geometry can also describe curved space-times and gravitational degrees of freedom, and since the beginning, there have been attempts to use it to get a quantum theory of gravity. Perhaps the new ideas described here, including especially the Euclidean point of view with its breaking of Euclidean rotational invariance, will indicate some new way forward for a twistor-based quantum gravity.</p>
<p><strong>Bonus (but related) links:</strong> For the last few months the CMSA at Harvard has been hosting a <a href="https://cmsa.fas.harvard.edu/literature-lecture-series/">Math-Science Literature Lecture Series</a> of talks. Many worth watching, but one in particular features Simon Donaldson discussing <em>The ADHM construction of Yang-Mills instantons</em> (video <a href="https://youtu.be/Ad1raKFJ_yY">here</a>, slides <a href="https://cmsa.fas.harvard.edu/wp-content/uploads/2020/05/harvard2020.pdf">here</a>). This discusses the Euclidean version of the twistor story, in the context it was used back in the late 1970s to relate solutions of the instanton equations to holomorphic bundles.</p>Tue, 11 Aug 2020 13:13:46 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110k50lVpcY5P331z8-xSOmNlJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oeMJ0nZwBmzxQuantization and Dirac Cohomology
https://api.follow.it/track-rss-story-click/AaY2ldA110kaHyybcBZXFTjq7PwYEWiNJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oZ8wOwuivxl1
<img src="https://api.follow.it/rssubscribers/rss_show_story_count/344305131/15156" border=0 width="1" height="1" alt="Story 344305131" title="Story 344305131"> <p>For many years I’ve been fascinated by the topic of “Dirac cohomology” and its possible relations to various questions about quantization and quantum field theory. At first I was mainly trying to understand the relation to BRST, and wrote some things here on the blog about that. As time has gone on, my perspective on the subject has kept changing, and for a long time I’ve been wanting to write something here about these newer ideas. Last year I gave a talk at Dartmouth, explaining some of my point of view at the time. Over the last few months I’ve unfortunately yet again changed direction on where this is going. I’ll write about this new direction here in some detail next week, but in the meantime, have decided to make available the <a href="https://www.math.columbia.edu/~woit/qmdirac-dartmouth-printable.pdf">slides from the Dartmouth talk</a>, and a version of the document I was writing on <a href="http://www.math.columbia.edu/~woit/qmdirac.pdf"> Quantization and Dirac Cohomology</a>.</p>
<p>Some warnings:</p>
<ul>
<li>Best to ignore the comments at the end of the slides about applications to Poincaré group representations and BRST. Both of these applications require getting the Dirac cohomology machinery to work in cases of non-reductive Lie algebras. As far as Poincaré goes, I’ve recently come to the conclusion that doing things with the conformal group (which is reductive) is both more interesting and works better. I’ll write more about this next week. For BRST, there is a lot one can say, but I likely won’t get back to writing more about that for a while.</li>
<li>The Quantization and Dirac Cohomology document is kind of a mess. It’s an amalgam of various pieces written from different perspectives, and some lecture notes from a course on representation theory. Some day I hope to find the time for a massive rewrite from a new perspective, but maybe some people will find interesting what’s there now.</li>
</ul>Fri, 07 Aug 2020 22:23:40 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110kaHyybcBZXFTjq7PwYEWiNJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oZ8wOwuivxl1(Imaginary) Time Asymmetry
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/344000153/15156" border=0 width="1" height="1" alt="Story 344000153" title="Story 344000153"> <p>When people write down a list of axioms for quantum mechanics, they typically neglect to include a crucial one: positivity (or more generally, boundedness below) of the energy. This is equivalent to saying that something very different happens when you Fourier transform with respect to time versus with respect to space. If $\psi(t,x)$ is a wavefunction depending on time and space, and you Fourier transform with respect to both time and space<br />
$$\widetilde{\psi}(E,p)=\frac{1}{2\pi}\int_{-\infty}^\infty \int_{-\infty}^\infty \psi(t,x)e^{iEt}e^{-ipx}dtdx$$<br />
(the difference in sign for $E$ and $p$ is just a convention) a basic axiom of the the theory is that, while $\widetilde{\psi}(E,p)$ can be non-zero for all values of $p$, it must be zero for negative values of $E$.</p>
<p>This fundamental asymmetry in the theory also becomes very apparent if you want to “Wick rotate” the theory. This involves formulating the theory for complex time and exploiting holomorphicity in the time variable. One way to do this is to inverse Fourier transform $\widetilde{\psi}(E,p)$ in $E$, using a complex variable $z=t+i\tau$:<br />
$$\widehat{\psi}(z,p)=\frac{1}{\sqrt{2\pi}}\int_{-\infty}^\infty \widetilde{\psi}(E,p)e^{-iEz} dE$$<br />
The exponential term in the integral will be<br />
$$e^{-iE(t+i\tau)}=e^{-iEt}e^{E\tau}$$<br />
which (since $E$ is non-negative) will only have good behavior for $\tau <0$, i.e. in the lower-half $z$-plane. Thinking of Wick rotation as involving analytic continuation of wave-functions from $z=t$ to $z=t+i\tau$, this will only work for $\tau <0$: there is a fundamental asymmetry in the theory for (imaginary) time.</p>
<p>If you decide to define a quantum theory starting with imaginary time and Wick rotating (analytically continuing) back to real, physical time at the end of a calculation, then you need to build in $\tau$ asymmetry from the beginning. One way this shows up in any formalism for doing this is in the necessity of introducing a $\tau$-refection operation into the definition of physical states, with the Osterwalder-Schrader positivity condition then needed in order to ensure unitarity of the the theory.</p>
<p>Why does one want to formulate the theory in imaginary time anyway? A standard answer to this question is that path integrals don’t actually make any sense in real time, but in imaginary time often become perfectly well-defined objects that can be thought of as expectation values in a statistical mechanical system. For a somewhat different answer, note that even for the simplest free particle theory, when you start calculating things like propagators you immediately run into integrals that involve integrating a function with a pole, for instance integrating over $E$ integrals with a term<br />
$$\frac{1}{E-\frac{p^2}{2m}}$$<br />
Every quantum mechanics and quantum field theory textbook has a discussion of what to do to make sense of such calculations, by defining the integral involved as a specific limit. The imaginary time formalism has the advantage of being based on integrals that are well-defined, with the ambiguities showing up only when one analytically continues to real time. Whether or not you use imaginary time methods, the real time objects getting computed are inherently not functions, but boundary values of holomorphic functions, defined of necessity as limits as one approaches the real axis.</p>
<p>A mathematical formalism for handling such objects is the theory of hyperfunctions. I’ve started writing up some notes about this, see <a href="http://www.math.columbia.edu/~woit/hyperfunctions.pdf">here</a>. As I find time, these should get significantly expanded. </p>
<p>One reason I’ve been interested in this is that I’ve never found a convincing explanation of how to deal with Euclidean spinor fields. Stay tuned, soon I’ll write something here about some ideas that come from thinking about that problem.</p>Thu, 06 Aug 2020 18:44:03 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110k7WzOhfWV-Q7V8HZmzB6MmJrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_oc3LNSFq_aSDYesterday’s Hype
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<img src="https://api.follow.it/rssubscribers/rss_show_story_count/342492460/15156" border=0 width="1" height="1" alt="Story 342492460" title="Story 342492460"> <p>Every summer CERN runs a <a href="https://summerstudent.web.cern.ch/home">summer student programme</a>, designed to bring in a group of students to participate in scientific activities at CERN and provide lectures for them about the basics and latest state of the field of high energy physics. Because of the COVID situation, this summer they have not been able to bring students in, but are providing instructional lectures and Q and A’s. <a href="https://summerstudent.web.cern.ch/lectures-2020">This year’s sessions</a> are based on having students follow materials from last year’s lectures, followed by a Q and A to answer their questions.</p>
<p>One of the topics the students are presented is <a href="https://summerstudent.web.cern.ch/lectures-2019/what-is-string-theory">What is String Theory?</a>, and you can watch the 2019 video or <a href="https://indico.cern.ch/event/817571/attachments/1865556/3110483/CERN-SummerSchool-2019.pdf">look at the slides</a>. Timo Weigand’s presentation can be accurately described as pure, unadulterated hype, with not a hint of the existence of any significant problem with ideas presented. In the <a href="https://videos.cern.ch/record/2725650">Q and A yesterday</a>, Weigand did come up with a new piece of “evidence for string theory”: it “predicts” no continuous spin representations.</p>
<p>I can’t begin to understand why anyone thinks it’s all right for CERN to subject impressionable students to this kind of thing. Someone, not me, should be complaining to the organizers and to CERN management.</p>
<p>This is unfortunately now an all too common example of what passes for “Sci Comm” in much of the field of fundamental physics: endless repetition of old discredited arguments in favor of a failed theory, coupled with pretending not to know about what is wrong with these arguments. The field that was once one of the greatest examples of the power of the human mind and the strength of the scientific method has become something very different and quite dangerous: all-too-visible ammunition for those who want to make the case that scientists are as deluded and tribalistic as anyone else, so not to be trusted.</p>Sat, 01 Aug 2020 15:23:04 GMThttps://api.follow.it/track-rss-story-click/AaY2ldA110m5HaCGpD945XawZ12B-dU6Jrrc4NnA57E12CUZTVS_YALR39lnjt6QowTKTCcIdhdI24M9rPM_obcXp7n6n2io