Not Even Wrong
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Tue, 26 Sep 2017 10:50:14 GMTFeedCreatorClass 1.0 dev (specificfeeds.com)Special Relativity and Classical Field Theory
http://www.math.columbia.edu/~woit/wordpress/?p=9514
<p>For quite a while Leonard Susskind has been giving some wonderful courses on physics under the name “The Theoretical Minimum”, pitched at a level in between typical popularizations and standard advanced undergraduate courses. This is a great idea, since there is not much else of this kind, while lots of people inspired by a popular book could use something more serious to start learning what is really going on. The courses are available as Youtube lectures <a href="http://theoreticalminimum.com/courses">here</a>.</p>
<p>Book versions of some of the courses have now appeared, first one (in collaboration with George Hrabovsky) about classical mechanics, then one (with Art Friedman) about quantum mechanics. I wrote a little bit about these <a href="http://www.math.columbia.edu/~woit/wordpress/?p=5487">here</a> and <a href="http://www.math.columbia.edu/~woit/wordpress/?p=6720">here</a>, thought they were very well done. When last in Paris I noticed that there’s now a French version of these two books (with a blurb from me for the quantum mechanics one).</p>
<p>The third book in the series (also with Art Friedman) is about to appear. It’s entitled <a href="https://www.amazon.com/Special-Relativity-Classical-Field-Theory/dp/0465093345">Special Relativity and Classical Field Theory</a>, and is in much the same successful style as the first two books. Robert Crease has a <a href="http://www.nature.com/nature/journal/v549/n7672/full/549331a.html">detailed and very positive review in Nature</a> which does a good job of explaining what’s in the book and which I’d mostly agree with.</p>
<p>The basic concept of the book is to cover special relativity and electromagnetism together, getting to the point of understanding the behavior of electric and magnetic fields under Lorentz transformations, and the Lorentz invariance properties of Maxwell’s equation. Along the way, there’s quite a lot of the usual sort of discussion of special relativity in terms of understanding what happens as you change reference frame, a lot of detailed working out of gymnastics with tensors, and some discussion in the Lagrangian language of the Klein-Gordon equation as a simpler case of a (classical) relativistic field theory than the Maxwell theory. Much of what is covered is clearly overkill if you just want to understand E and M, but undoubtedly is motivated by his desire to go on to general relativity in the next volume in this series.</p>
<p>At various points along the way, the book provides a much more detailed and leisurely explanation of crucial topics that a typical textbook would cover all too quickly. This should be very helpful for students (perhaps the majority?) who have trouble following what’s going on in their textbooks or course due to not enough detail or motivation. Besides non-traditional students in a course of self-study, the book may be quite useful for conventional students as a supplement to their textbook.</p>
<p>One of the most annoying things someone can do while reviewing a book is to start going on about their own different take on the material, criticizing the author for not writing a very different book. So, the rest of this posting is no longer a review of the book, it’s now about the very different topic of what I think about this material, nothing to do with Susskind’s valuable and different approach.</p>
<p>This semester I’m teaching a graduate level course on geometry, and by chance the past week have been discussing exactly some of the same material about tensor fields that Susskind covers. The perspective is quite different, starting with trying to explain a coordinate-invariant point of view on what these things are, only then getting to the formalism Susskind discusses. I can’t help thinking that, with all the effort Susskind (and pretty much every other physics textbook…) devotes to endless gymnastics with tensors in coordinates, they could instead be providing an understanding of the geometry behind this story. It’s unfortunate that many if not most of those who study this material in physics don’t ever get exposed to this point of view. Thinking in geometrical terms, the vector potential and field strength have relatively simple interpretations, and using differential forms the equations needed for the part of E and M Susskind covers are pretty much just:</p>
<p>F=dA, dF=0, and d*F=*J</p>
<p>Similarly, for the special relativity material, there’s a danger of the basic simplicity of the story getting lost in calculations of how things appear in coordinates with respect to different reference frames. What you fundamentally need is mainly that objects are described by a (conserved in the absence of forces) energy-momentum p, which satisfies p<sup>2</sup>= -m<sup>2</sup>, with Lorentz transformations taking one such p to another. The wider principle is that things are described by solutions to wave equations, with special relativity saying that the Lorentz group takes solutions to solutions.</p>
<p>I’d like to believe that such a very different course and very different book would be possible, quite possibly am very wrong (I’ve never taught special relativity to anyone). Maybe some day someone, inspired by Susskind’s project, might try to do something at a similar level, but from a more geometric point of view.</p>
Fri, 22 Sep 2017 17:29:49 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9514QCD at $\theta=\pi$
http://www.math.columbia.edu/~woit/wordpress/?p=9509
<p>Earlier this week Zohar Komargodski (who is now at the Simons Center) visited Columbia, and gave a wonderful talk on recent work he has been involved in that provides some new insight into a very old question about QCD. Simplifying the problem by ignoring fermions, QCD is a pure SU(3) Yang-Mills gauge theory, a simple to define QFT which has been highly resistant to decades of effort to better understand it. </p>
<p>One aspect of the theory is that it can be studied as a function of an angular parameter, the so-called $\theta$-angle. Most information about the theory comes from simplifying by taking $\theta=0$, which seems to be the physically relevant value, one at which the theory is time reversal invariant. There is however another value for which the theory is time reversal invariant, $\theta=\pi$, and what happens there has always been rather mysterious.</p>
<p>The new ideas about this question that Komargodski talked about are in the paper <a href="https://arxiv.org/abs/1703.00501">Theta, Time Reversal and Temperature</a> from earlier this year, joint work with Gaiotto, Kapustin and Seiberg. Much of the talk was taken up with going over the details of the toy model described in Appendix D of this paper. This is an extremely simple quantum mechanical model, that of a particle moving on a circle, where you add to the Lagrangian a term proportional to the velocity, which is where the angle $\theta$ appears. You can also think of this as a coupling to an electromagnetic field describing flux through the circle.</p>
<p>Even if you’re put off by the difficulty of questions about quantum field theories such as QCD, I strongly recommend reading their Appendix. It’s a simple and straightforward quantum mechanics story, with the new feature of a beautiful interpretation of the model in terms of a projective representation of the group O(2), or equivalently, a representation of Pin(2), a central extension of O(2). In the analogy to SU(N) Yang-Mills, it is the $\mathbf Z_N$ symmetry of the theory that gets realized projectively.</p>
<p>Komargodski himself commented at the beginning of the talk on the reasons that people are returning to look again at old, difficult problems about QCD. The new ideas he described are closely related to ones that are part of the recent hot topic of symmetry protected phases in condensed matter theory. It’s great to see that this QFT research may not just have condensed matter applications, but seems to be leading to a renewal of interest in long-standing problems about QCD itself. </p>
<p>Besides the paper mentioned above, there are now quite a few others. One notable one is very recent work of Komargodski and collaborators, <a href="https://arxiv.org/abs/1708.06806">Time-Reversal Breaking in QCD4, Walls and Dualities in 2+1 Dimensions</a>. </p>
Fri, 15 Sep 2017 21:55:53 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9509Modern Theories of Quantum Gravity
http://www.math.columbia.edu/~woit/wordpress/?p=9505
<p>Quanta magazine today has a <a href="https://www.quantamagazine.org/to-solve-the-biggest-mystery-in-physics-join-two-kinds-of-law-20170907/">column by Robbert Dijkgraaf</a> that comes with the abstract:</p>
<blockquote><p>Reductionism breaks the world into elementary building blocks. Emergence finds the simple laws that arise out of complexity. These two complementary ways of viewing the universe come together in modern theories of quantum gravity.</p></blockquote>
<p>It struck me that at this point I don’t know what a “modern theory of quantum gravity” is. Much of the article is a clear explanation of the usual story of the renormalization group and effective field theory, but towards the end, when quantum gravity comes up, I have trouble following. String theory has gone from being an exciting new idea to being part of historical tradition:</p>
<blockquote><p>
Traditional approaches to quantum gravity, such as perturbative string theory, try to find a fully consistent microscopic description of all particles and forces. Such a “final theory” necessarily includes a theory of gravitons, the elementary particles of the gravitational field. </p></blockquote>
<p>That “reductionist” tradition is opposed to a new “emergent” holographic theory, and we’re told that</p>
<blockquote><p>The present point of view thinks of space-time not as a starting point, but as an end point, as a natural structure that emerges out of the complexity of quantum information, much like the thermodynamics that rules our glass of water. Perhaps, in retrospect, it was not an accident that the two physical laws that Einstein liked best, thermodynamics and general relativity, have a common origin as emergent phenomena.</p>
<p>In some ways, this surprising marriage of emergence and reductionism allows one to enjoy the best of both worlds. For physicists, beauty is found at both ends of the spectrum.
</p></blockquote>
<p>Dijkgraaf seems to be saying that a viable emergent theory of four-dimensional quantum gravity based on the complexity of quantum information has been found, but I seem to have missed this. Can someone point me to a paper describing it?</p>
Fri, 08 Sep 2017 01:53:32 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9505Modern Geometry
http://www.math.columbia.edu/~woit/wordpress/?p=9502
<p>This semester I’m teaching the first semester of Modern Geometry, our year-long course on differential geometry aimed at our first-year Ph.D. students. A syllabus and some other information about the course is available <a href="http://www.math.columbia.edu/~woit/geometry2017/">here</a>.</p>
<p>In the spring semester Simon Brendle will be covering Riemannian geometry, so this gives me an excuse to spend a lot of time on aspects of differential geometry that don’t use a metric. In particular, I’ll cover in detail the general theory of connections and curvature, rather than starting with the Levi-Civita connection that shows up in Riemannian geometry. I’ll be starting with connections on principal bundles, only later getting to connections on vector bundles. Most books do this in the other order, although <a href="https://en.wikipedia.org/wiki/Foundations_of_Differential_Geometry">Kobayashi and Nomizu</a> does principal bundles first. In some sense a lot of what I’ll be doing is just explicating Kobayashi and Nomizu, which is a great book, but not especially user-friendly.</p>
<p>A major goal of the course is to get to the point of writing down the main geometrically-motivated equations of fundamental physics and a few of their solutions as examples. This includes the Einstein eqs. of general relativity, although I’ll mostly be leaving that topic to the second semester course.</p>
<p>Ideally I think every theoretical physicist should know enough about geometry to appreciate the geometrical basis of gauge theories and general relativity. In addition, any geometer should know about how geometry gets used in these two areas of physics. I’ve off and on thought about writing an outline of the subject aimed at these two audiences, and thought about writing something this semester. Thinking more about it though, at this point I’m pretty sick of expository writing (proofs of my QM book are supposed to arrive any moment…). In addition, I just took a look again at the 1980 review article by Eguchi, Gilkey and Hanson (see <a href="http://www.sciencedirect.com/science/article/pii/0370157380901301">here</a> or <a href="https://www.cs.indiana.edu/~hansona/papers/EguchiGilkeyHanson1980.pdf">here</a>) from which I first learned a lot of this material. It really is very good, and anything I’d write would spend a lot of time just reproducing that material.</p>
Mon, 04 Sep 2017 19:11:15 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9502This and That
http://www.math.columbia.edu/~woit/wordpress/?p=9492
<ul>
<li>The <a href="http://stacks.math.columbia.edu/">Stacks Project</a> (see an earlier post <a href="http://www.math.columbia.edu/~woit/wordpress/?p=6164">here</a>) had a very successful <a href="https://stacks.github.io/">workshop</a> in Ann Arbor earlier this month. This is a remarkable effort pioneered by Johan de Jong to produce a high quality open source reference for the field of algebraic geometry. It now is over 6000 pages, with an increasingly large number of papers citing it (according to <a href="https://stacks.github.io/slides.pdf">data from Pieter Belmans</a>, 85 citations in the arXiv so far in 2017 alone). During the workshop plans were discussed for the future of the project, with work on a new version of the project infrastructure underway (see <a href="https://stacks.github.io/framework.pdf">slides</a> and a <a href="http://pbelmans.ncag.info/blog/2017/08/27/introduction-gerby-plastex/">blog post</a> from Belmans).</li>
<li>The latest AMS Notices has a <a href="http://www.ams.org/publications/journals/notices/201708/rnoti-p892.pdf">wonderful article</a> by my Barnard/Columbia colleague Dusa McDuff about her remarkable family history and reflecting on her equally remarkable mathematical career. A <a href="http://www.math.columbia.edu/~woit/wordpress/?p=9110">post earlier this year</a> discussed a Quanta article about her recent work with Katrin Wehrheim on technical issues in the foundations of symplectic topology. Kenji Fukaya has recently written something for the Simons Center website (see <a href="http://scgp.stonybrook.edu/archives/22091">here</a>) explaining his take on this story.</li>
<li>The Stanford Encyclopedia of Philosophy has a <a href="https://seop.illc.uva.nl/entries/fine-tuning/">new entry about the fine-tuning problem</a>, by Simon Friedrich.</li>
<li>The LHC operators have run into some difficulty in recent weeks (reflected in the accumulated luminosity plots <a href="https://cms-service-lumi.web.cern.ch/cms-service-lumi/publicplots/int_lumi_per_day_cumulative_pp_2017OnlineLumi.png">here</a> and <a href="https://atlas.web.cern.ch/Atlas/GROUPS/DATAPREPARATION/PublicPlots/2017/DataSummary/figs/sumLumiByDay.png">here</a>), with problems centered around an unknown source of gas in the beam pipe at a specific location, leading to losses of the beam. Some information about this is available <a href="https://home.cern/cern-people/updates/2017/08/lhc-report-something-nothing">here</a>. The past few days they seem to be having success running the machine with around 1500 bunches, much less than the 2500 or so of earlier in the summer. The target for the year is 40 inverse fb which may still be achieved, while more optimistic numbers that looked plausible earlier now seem less likely.</li>
</ul>
Tue, 29 Aug 2017 23:38:40 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9492Road Trip
http://www.math.columbia.edu/~woit/wordpress/?p=9481
<p>Blogging will be light to non-existent for the next ten days or so, as I head out west on a road trip to see next Monday’s solar eclipse. Current plan is to fly to Denver tomorrow, pick up a vehicle, and head up to Wyoming the next day. If weather projections look good for the Wyoming/Idaho part of the track, that’s where we’ll plan to end up, likely camping out somewhere (accommodations along the track have long been booked up).</p>
<p>This will be the ninth eclipse I’ve traveled to see, and I urge anyone thinking of making a trip to the eclipse track to do so. A total solar eclipse is something quite different than a partial one, and this is a very rare opportunity to see this in the US. Besides the eclipse, a major motivation for these trips has always been that of getting to visit a more or less random place on Earth that one wouldn’t otherwise have any excuse to see. I’ve driven quickly through Idaho and Wyoming a few times over the years, look forward to spending more time in that part of the country this coming week (unless the weather there looks bad, in which case maybe we’ll end up in Oregon or Nebraska).</p>
<p>Some other random advice about eclipses:</p>
<ul>
<li>Be very careful about use of binoculars or telescopes, improper use of these at any time other than the period of totality is what can cause serious eye damage (by itself the eye is pretty good about automatically protecting itself).</li>
<li>Don’t put a lot of effort into photography during totality, since that’s likely to lead to you spending the time you should be enjoying the experience fiddling with camera equipment (and not getting a good result anyway…). A simple thing to do is to set up a camera to take video of the overall eclipse scene as it happens, turn it on at some point then ignore it.</li>
</ul>
<p>If you miss this one, next couple are far south in South America, there will be another chance in the US relatively soon, April 2024.</p>
Mon, 14 Aug 2017 14:57:13 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9481GR=QM?
http://www.math.columbia.edu/~woit/wordpress/?p=9474
<p>In recent years a hot topic in some theoretical physics circles has been the 2013 “ER=EPR” conjecture first discussed by Maldacena and Susskind <a href="https://arxiv.org/abs/1306.0533">here</a>. Every so often I try and read something explaining what this is about, but all such efforts have left me unenlightened. I’m left thinking it best to wait for this to be better understood and someone produce a readable exposition.</p>
<p>Instead of that happening, it seems that the field is moving ever forward in a post-modern direction I can’t follow. Tonight the arXiv has something <a href="https://arxiv.org/abs/1708.03040">new from Susskind</a> about this, where he argues that one should go beyond “ER=EPR”, to “GR=QM”. While the 2013 paper had very few equations, this one has none at all, and is actually written in the form not of a scientific paper, but of a letter to fellow “Qubitzers”. On some sort of spectrum of precision of statements, with Bourbaki near one end, this paper is way at the other end.</p>
<p>Susskind starts out:</p>
<blockquote><p>It is said that general relativity and quantum mechanics are separate subjects that don’t fit together comfortably. There is a tension, even a contradiction between them—or so one often hears. I take exception to this view. I think that exactly the opposite is true. It may be too strong to say that gravity and quantum mechanics are exactly the same thing, but those of us who are paying attention, may already sense that the two are inseparable, and that neither makes sense without the other.</p></blockquote>
<p>I just finished writing a book about quantum mechanics, and it all seemed to me to make perfect sense without invoking gravity, but as explained above I guess I’m one of those who is not (successfully) paying attention. Another route to understanding would be to focus on the new experimental implications of the ideas. In the abstract Susskind claims that his ideas imply that we’ll observe quantum gravity using quantum computers in a lab “sometime in the next decade or so”. When that happens maybe this will all become clearer.</p>
Fri, 11 Aug 2017 01:27:49 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9474Cosmology for the Curious
http://www.math.columbia.edu/~woit/wordpress/?p=9469
<p>There’s a new college-level textbook out, <a href="http://www.springer.com/us/book/9783319570389">Cosmology for the Curious</a>, targeted at physics courses designed to explain basics of cosmology to non-physics majors. The authors are Delia Perlov and Alex Vilenkin. Back in 2006 Vilenkin published a popular book promoting the multiverse, <a href="http://www.math.columbia.edu/~woit/wordpress/?p=425">Many Worlds in One</a>, which I wrote about at the time, making the obvious comment that there was nothing like a testable experimental prediction to be found in the book. It seemed to me then that the physics community would never take seriously an inherently untestable theory, recognizing such a thing as pseudo-science. I thought that the only reason claims like those of Vilenkin were getting any attention was that they had some novelty. Surely after a few more years of attempts to extract a prediction of some sort led to nothing, the emptiness of this sort of idea would become clear to all and everyone would lose interest.</p>
<p>Eleven years later I’m as baffled by what has happened to the field of fundamental physics as I’m baffled by what has happened to democracy in the US. As all attempts to extract a testable prediction from the multiverse have failed, instead of going away, pseudo-science has become <a href="http://www.math.columbia.edu/~woit/wordpress/?cat=10">ever more dominant</a>, with a hugely successful publicity campaign (including a lot of <a href="http://www.math.columbia.edu/~woit/wordpress/?p=9053">“Fake Physics”</a>) overcoming scientific failure. Now this sort of thing is moving from speculative pop science to getting the status of accepted science, taught as such to undergraduates.</p>
<p>Many are worried about the status of science in our society, as it faces new challenges. I don’t see how the physics community is going to continue to have any credibility with the rest of society if it sits back and allows multiverse mania to enter the canon. Non-scientists taking science classes need to be taught about the importance of always asking: what would it take to show that this theory is wrong? how do I know this is science not ideology?</p>
<p>Any student who reads this textbook and looks for answers to these questions in it will find just two “tests” of the multiverse proposed:</p>
<ul>
<li>Look for evidence of bubble collisions.</li>
<li>Believe <a href="https://arxiv.org/abs/1512.01819">this paper</a>, and then if you find a black hole population with a certain kind of mass spectrum, that would be evidence for the multiverse.</li>
</ul>
<p>Of course there is no evidence for bubble collisions or such a black hole population, but these are no-lose “tests”: no matter what you observe or don’t observe, the multiverse “theory” can only win, it can never lose. Is it really a good idea to teach courses telling college students that this is how science works?</p>
Wed, 09 Aug 2017 01:36:09 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9469Quick Links
http://www.math.columbia.edu/~woit/wordpress/?p=9465
<ul>
<li>For representation theory aficionados, George Lusztig has put on the arXiv a long document with <a href="https://arxiv.org/abs/1707.09368">comments on his papers</a> (for a bit more about him, see <a href="http://www.math.columbia.edu/~woit/wordpress/?p=402">this</a>).</li>
<li>For a new idea exemplifying the potential grand unification of mathematics and physics, Minhyong Kim and others have been developing arithmetic Chern-Simons theory (see <a href="https://arxiv.org/abs/1510.05818">here</a> and <a href="https://arxiv.org/abs/1609.03012">here</a>). There was a <a href="http://homepage.divms.uiowa.edu/~fbleher/CSMeeting2017.html">recent workshop</a> on the topic, videos of talks available <a href="https://www.youtube.com/channel/UCxgeCyy-iHr9T1RMT9OHMLw">here</a>.</li>
<li>The editors of the Journal of Algebraic Combinatorics are leaving the Springer journal, setting up a new journal, Algebraic Combinatorics. For more about this, there’s a <a href="http://www.mathoa.org/press/">press release</a>, a <a href="https://www.insidehighered.com/news/2017/07/31/math-journal-editors-resign-start-rival-open-access-journal">story at Inside Higher Education</a>, and a <a href="https://gowers.wordpress.com/2017/07/27/another-journal-flips/">blog entry by Timothy Gowers</a>.</li>
<li>Landon Clay, founder of the Clay Mathematics Insitute, passed away last week, more about him available <a href="http://www.claymath.org/landon-clay-founder-clay-mathematics-institute">here</a>.</li>
<li>There’s a profile and interview with Carlo Rovelli <a href="http://www.huckmagazine.com/art-and-culture/print/transformative-books/activist-scientist-physics-reality-carlo-rovelli-interview/">here</a>.</li>
<li>While Google continues to develop our new machine overlords, Google money will fund a <a href="https://www.math.ias.edu/theoretical_machine_learning">new IAS program</a> to address their theoretical underpinnings.</li>
</ul>
Fri, 04 Aug 2017 19:29:45 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9465A Few Items
http://www.math.columbia.edu/~woit/wordpress/?p=9457
<p>Just a few items:</p>
<ul>
<li>The Simons Foundation has announced a new <a href="https://www.simonsfoundation.org/features/foundation-news/new-initiative-ponders-origins-of-the-universe/">Origins of the Universe</a> initiative, which will fund efforts to “develop testable predictions about string theory, quantum gravity and a cosmological ‘Big Bounce.'” I don’t think even all of Jim Simons’ money will be enough to fund a real “prediction of string theory”, but the fake kind can be had rather cheaply. I was interested to see in <a href="https://science.energy.gov/~/media/hep/hepap/pdf/201706/Saul_Gonzalez_Division_of_Physics_HEPAP_June-2017.pdf">this presentation from the NSF</a> that grants from Simons and other private sources are starting to change the way they do business:<br />
<blockquote><p> One major challenge affecting Theory is the entrance of non-traditional (private philanthropic) funding sources. NSF has developed new procedures for evaluating overlapping sources of funding and introducing such evaluations into the proposal review process.</p></blockquote>
<p>I’m curious how they are dealing with this. If someone is being funded by Simons, will the NSF/DOE also fund them? Will the NSF/DOE stop funding fields that are being heavily financed by Simons/Templeton/Kavli? Does this have anything to with the NSF/DOE cuts in HEP theory funding of recent years?</li>
<li>The latest AMS Notices has a couple of articles about gravitational radiation, see <a href="http://www.ams.org/journals/notices/201707/rnoti-p684.pdf">here</a>.</li>
<li>Yesterday a two week graduate summer school on automorphic forms and the Langlands program started. Lectures are being given by Kevin Buzzard and are on video <a href="http://www.msri.org/summer_schools/792/schedules">here</a>. Buzzard has set up a web-site for the lectures <a href="http://wwwf.imperial.ac.uk/~buzzard/MSRI">here</a>.
<p>In his first lecture he explained that Richard Taylor’s CalTech lectures in 1992 (scans of Buzzard’s notes <a href="http://wwwf.imperial.ac.uk/~buzzard/MSRI/Taylor_Caltech_1992_secondtry.pdf">here</a>) had a huge effect on him, and the plan of his lectures is to cover an updated version of some of the same material, ending up by getting to the latest developments, now available solely on a blog <a href="https://galoisrepresentations.wordpress.com/2017/06/23/new-results-in-modularity-part-i/">here</a> and <a href="https://galoisrepresentations.wordpress.com/2017/06/23/new-results-in-modularity-part-ii/">here</a>. Buzzard also explained that in 1992 he devoted his time in LA to working on understanding the lectures during the week, going to raves on weekends. No news on whether MSRI is making similar arrangements for weekend activities of students in the summer school.
</li>
<li>Two new articles from Michael Harris: <a href="http://www.math.columbia.edu/~harris/otherarticles_files/perfectoid.pdf">The Perfectoid Concept: Test Case for an Absent Theory</a> and <a href="http://www.math.columbia.edu/~harris/otherarticles_files/Responsibilities.pdf">Do Mathematicians Have Responsibilities?</a>.</li>
</ul>
Tue, 25 Jul 2017 18:13:22 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9457What the Hell is Going On?
http://www.math.columbia.edu/~woit/wordpress/?p=9444
<p>I’ve looked at the talks from a few of the HEP experiment and phenomenology summer conferences. If anyone can point me to anything interesting that I’ve missed, please do so. The lack of new physics beyond the Higgs at the LHC has left the field in a difficult state.</p>
<p>One conference going on this past week and next is the IAS PiTP summer program aimed at advanced grad students and postdocs. This year the topic is HEP phenomenology, and talks are available <a href="https://pitp.ias.edu/program-schedule">here</a>. If you want to understand the conventional wisdom on the state of the subject, you can watch Nima Arkani-Hamed’s three and a half hour lecture (<a href="https://www.youtube.com/watch?v=dKVXxcbJ4YY">here</a> and <a href="https://www.youtube.com/watch?v=mRMF4b0GcCw">here</a>) which he starts off by describing as on the topic “What the Hell is Going On?”.</p>
<p>A lot of the first part is historical, starting off with the Georgi-Glashow GUT and the arguments for SU(5) or SO(10) GUT unification first put forward 43 years ago. He then walks the audience through the sequence of steps theorists have taken to solve the problems of such models, after an hour ending up at the landscape, spending a half an hour promoting the anthropic solution to the CC and other problems. The second part of the talk is largely devoted to making the case for his favored split SUSY models, with anthropics and the landscape taking care of their naturalness problems. By the end of the three and a half hours, Arkani-Hamed admits that this scenario is not that convincing, while arguing that it’s the only thing he can see left that is consistent with the idea that theorists have been following a correct path since 1974:</p>
<blockquote><p>It’s the only picture of the world that I know where everything that we learned experimentally and theoretically for the last 30 years has some role to play in it. But my confidence in it is not so super high, and I definitely think its worth thinking about completely radically different things.</p>
<p>The disadvantage to the trajectory of going with what works and then changing a little and changing a little is that you might just be in the basin of attraction of the wrong idea from the start and then you’ll just stay there for ever.</p></blockquote>
<p>To me by now the evidence is overwhelming that HEP theory has been in the wrong basin of attraction for quite a while, and the overriding question is what can be done to get out of it. If you’re in the wrong basin of attraction, you need to get out of it by going back to the point where you entered it and looking for another direction. I think Arkani-Hamed is right to identify the 1974 GUT hypothesis as the starting point that led the field into this wrong basin. HEP theory has progressed historically by identifying new more powerful symmetry principles. The move in 1974 was to go beyond the SM symmetries by picking a larger gauge group, then breaking it at a very high energy scale with new scalar fields. The history of the last 43 years is that this idea isn’t a successful one: as this talk shows, it leads to an empty theory that explains nothing. Can one find different new ideas about symmetry that are more promising?</p>
Sat, 22 Jul 2017 19:31:26 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9444Summer Conferences: Physical Mathematics
http://www.math.columbia.edu/~woit/wordpress/?p=9435
<p>I’ve finally found some time to look around the web to see what has been happening at conferences this summer. In this blog post I’ll point to a few on the math/physics interface featuring interesting talks. This area now (I think it may be Greg Moore’s fault) has started to acquire the name of “Physical Mathematics”, to distinguish itself from old-school “Mathematical Physics”. At this point though I’d be hard-pressed to provide a useful definition of either term.</p>
<ul>
<li>Talks from last month’s 2017 Bonn Arbeitstagung are available <a href="https://www.mpim-bonn.mpg.de/node/7426">here</a>. This conference was in honor of Yuri Manin and supposedly devoted to Physical Mathematics (although I suspect some of the speakers might not realize that they are doing Physical Mathematics). Dan Freed and Jacob Lurie gave two characteristically lucid series of talks, well worth watching.
<p>A very active area of physics these days with significant overlap with mathematics (of the sort discussed by Freed) is the study of topological superconductors and other materials in which topology plays a large role. For an introduction to this topic, Davide Castelvecchi at Nature has a new article <a href="https://www.nature.com/news/the-strange-topology-that-is-reshaping-physics-1.22316">The strange topology that is reshaping physics</a>.
</li>
<li>CERN has just finished running an institute on the topic of the <a href="https://indico.cern.ch/event/611006/timetable/">Geometry of String and Gauge Theories</a>. It included a colloquium talk by Greg Moore on <a href="https://indico.cern.ch/event/611006/contributions/2644355/attachments/1492759/2321063/CERN-Colloquium-July12-2017.pdf">d=4 N=2 Field Theory and Physical Mathematics</a>. I’ve always been fascinated by the d=4 N=2 super Yang-Mills theory in its “twisted” topological version. The mathematics involved is deep and amazing, and it is frustratingly close to the Standard Model…</li>
<li><a href="http://grk1670.math.uni-hamburg.de/sms2017/">Pre-string math 2017</a> was this past week, and <a href="https://stringmath2017.desy.de/e45470/e56367/infoboxContent56368/SMabstr2.pdf">String Math 2017</a> will be next week. All sorts of interesting talks at both of these, relatively few of which have much to do with string theory. That’s of course also true of Strings 2017, but I’ll write about that elsewhere.</li>
</ul>
<p>Other suggestions of interesting mathematically related summer schools with talks available are welcome. On the physics side, please wait for a succeeding blog entry on that topic.</p>
Fri, 21 Jul 2017 19:56:56 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9435This Week’s Hype
http://www.math.columbia.edu/~woit/wordpress/?p=9426
<p>Commenter CIP <a href="http://www.math.columbia.edu/~woit/wordpress/?p=9409#comment-226350">pointed out</a> that today’s New York Times has one of the worst examples of string theory hype I’ve seen in a while. Based on <a href="https://arxiv.org/abs/1703.10682">this observation</a> of an expected QFT anomaly effect in a condensed matter system, the NYT has an article <a href="https://www.nytimes.com/2017/07/19/science/mixed-axial-gravitational-anomaly-weyl-semimetals-ibm.html">An Experiment in Zurich Brings Us Nearer to a Black Hole’s Mysteries</a>. Not only is the headline nonsense, but the article ends with</p>
<blockquote><p>The experiment is also a success for string theory, a branch of esoteric mathematics that physicists have used to try to tie gravity into the Standard Model, the laws of physics that describe the other forces in the universe. But string theory has been maligned because it makes predictions that cannot be tested.</p>
<p>Here, Dr. Landsteiner said, string theory was used to calculate the expected anomaly. “It puts string theory onto a firm basis as a tool for doing physics, real physics,” he said. “It seems incredible even to me that all this works, falls all together and can be converted into something so down to earth as an electric current.”</p></blockquote>
<p>There’s no connection at all to string theory here. The NYT seems to have been taken in by string theorist Landsteiner and <a href="https://finance.yahoo.com/news/ibm-scientists-observe-elusive-gravitational-182600873.html">press release hype like this</a>, not noticing that the paper had no mention of string theory in it. The hype is timed to the paper’s <a href="http://www.nature.com/nature/journal/v547/n7663/full/nature23005.html">publication in Nature</a>, where the editor’s summary gets it right, referring to QFT not string theory:</p>
<blockquote><p>Johannes Gooth et al. now provide another intriguing connection to quantum field theory. They show that a condensed-matter analogue of curved space time can add an additional, gravitational component to the chiral anomaly in Weyl semimetals. The work opens the door to further experimental exploration of previously undetected quantum field effects.</p></blockquote>
<p>Someone really should contact the NYT and get them to issue a correction. In particular, any string theorists who care about the credibility of their field should be doing this. </p>
Wed, 19 Jul 2017 21:15:10 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9426Various Links
http://www.math.columbia.edu/~woit/wordpress/?p=9373
<p>Some links to things that may be of interest:</p>
<ul>
<li>There’s an excellent <a href="https://fivethirtyeight.com/features/math-has-no-god-particle/">article at FiveThirtyEight</a> about the issue of publicizing math research, taking as example the <a href="http://www.liegroups.org/">Atlas of Lie Groups and Representations</a> project (which will soon be having a <a href="http://www.liegroups.org/workshop2017/workshop/">workshop</a>). This kind of thing generally gets no public attention, while at the same time, one of the results of this research arguably got too much public attention (see <a href="http://www.math.columbia.edu/~woit/wordpress/?p=534">here</a>).</li>
<li>There’s a new \$1 million mathematics prize that will be awarded for the first time this fall, together with a $1 million physics prize that was awarded for the first time last year. This is called the <a href="https://futureprize.org/eng">Future Science Prize</a>, and to get it you need to be working in China. Used to be a \$1 million prize was a big deal, now with the \$3 million <a href="https://breakthroughprize.org/">Breakthrough Prizes</a>, a mere million looks like small potatoes.</li>
<li>Another way you could get a measly \$1 million would be to prove (or disprove) the Hodge conjecture. For some inspiration, see Burt Totaro’s new <a href="http://www.ams.org/journals/bull/0000-000-00/S0273-0979-2017-01588-1/home.html">survey of progress on the Tate conjecture</a> (blog entry <a href="https://burttotaro.wordpress.com/2017/06/20/new-review-paper-recent-progress-on-the-tate-conjecture/">here</a>).</li>
<li>4 gravitons has a <a href="https://4gravitons.wordpress.com/2017/06/09/you-cant-smooth-the-big-bang/">nice posting</a> about work by Turok and others about complexified path integrals and cosmology. The issue of the relation between Euclidean and Minkowski signature QFT is one that I think has gotten far too little attention over the years. Now that I’ve finished writing a book with a QFT discussion that sticks to Minkowski space, I’m hoping to work on writing something about the relation to Euclidean space.</li>
<li>There’s an interview with Nima Arkani-Hamed <a href="https://www.pri.org/stories/2017-06-08/physicist-who-always-dreamed-working-us-says-it-s-no-longer-global-center-science">here</a>. His <a href="https://indico.cern.ch/event/617679/contributions/2614659/attachments/1482280/2299162/05-Arkani-Hamed.pdf">talk</a> at the recent <a href="https://indico.cern.ch/event/617679/timetable/#all.detailed">PASCOS 2017</a> conference (real title is second slide “What the Hell is Going On?”) gives his take on the current state of HEP, post failure of the LHC to find SUSY. He’s sticking with his 2004 “Split SUSY” as his “Best Bet”. I’d like to think his inspirational ending claiming that the negative LHC results are forcing people to rethink the foundations of the subject, asking again the question “What is QFT?” reflects reality, but not sure I see much of that.</li>
<li>This year’s LHC startup has been going well, with new a new luminosity record already set, and 6 inverse fb of data already collected. For more, see <a href="http://www.ibtimes.com/cern-lhc-update-large-hadron-collider-breaks-record-circulating-proton-bunches-2561117">here</a>.</li>
<li>Remember that “dark flow” that was supposed to be in the CMB data and evidence for the multiverse (see <a href="http://www.math.columbia.edu/~woit/wordpress/?p=5907">here</a>)? Still not there, <a href="https://arxiv.org/abs/1707.00132">according to Planck</a> (via <a href="https://twitter.com/WKCosmo/status/882186467589713921">Will Kinney</a>).</li>
</ul>
Thu, 06 Jul 2017 23:01:46 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9373Last Week’s Hype
http://www.math.columbia.edu/~woit/wordpress/?p=9409
<p>Now back from vacation, more regular blogging should resume imminently. While away, lots of press stories about claims that LIGO could be used to get “evidence for string theory”. As usual, these things can be traced back to misleading statements in a <a href="https://arxiv.org/abs/1704.07392">paper</a> and the associated <a href="http://www.aei.mpg.de/2070241/hints-of-extra-dimensions-in-gravitational-waves">university press release</a>. In this case, there had already been an <a href="https://www.newscientist.com/article/mg23431244-200-gravitational-waves-could-show-hints-of-extra-dimensions/">initial round of hype</a>, <a href="http://backreaction.blogspot.com/2017/05/can-we-use-gravitational-waves-to-rule.html">debunked by Sabine Hossenfelder</a>. The new round seems to have been generated by the June 28 press release. The Guardian has<a href="https://www.theguardian.com/science/2017/jul/05/gravitational-waves-string-theory"> a version of this</a>, but at least there the author found someone to make the obvious point, that this is irrelevant to string theory.</p>
Thu, 06 Jul 2017 18:55:13 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9409This Week’s Hype
http://www.math.columbia.edu/~woit/wordpress/?p=9405
<p>I’m on vacation in Europe, not in any mood to spend more time on this than just to point out that it’s the same usual tedious string theory promotional operation from the same people who have been at this for decades now. We have</p>
<ul>
<li>A PRL publication that has nothing at all to do with string theory, preprint <a href="https://arxiv.org/abs/1702.05490" target="_blank">here</a>. This is about a purely classical pde calculation in coupled EM + gravity.</li>
<li>The researcher’s university puts out a <a href="http://www.cam.ac.uk/research/news/saddle-shaped-universe-could-undermine-general-relativity" target="_blank">press release</a>.</li>
<li>A <a href="https://www.quantamagazine.org/where-gravity-is-weak-and-naked-singularities-are-verboten-20170620/" target="_blank">story then appears</a> where the usual suspects claim this is some sort of vindication for string theory and shows their loop quantum gravity opponents are wrong. There’s a lot of quite good information in the story about the actual classical calculation involved, but no indication of why one might want to be skeptical about the effort to enlist this result in the string vs. loop war.</li>
</ul>
<p>While traveling I’ve seen a couple very good stories about physics online:</p>
<ul>
<li>A <a href="https://www.nytimes.com/2017/06/19/science/cern-large-hadron-collider-higgs-physics.html" target="_blank">summary from Dennis Overbye</a> about the the current status of energy frontier HEP.</li>
<li>An <a href="https://aeon.co/essays/the-quantum-view-of-reality-might-not-be-so-weird-after-all" target="_blank">excellent long article by Philip Ball</a> about quantum mechanics and the measurement problem.</li>
</ul>
Thu, 22 Jun 2017 08:59:44 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9405This Time It’s Really for Real
http://www.math.columbia.edu/~woit/wordpress/?p=9395
<p>Twice now I’ve thought I had a finished version of the <a href="http://www.math.columbia.edu/~woit/QMbook/qmbook.pdf">book I’ve been writing forever</a> (see <a href="http://www.math.columbia.edu/~woit/wordpress/?p=8844">here</a> and <a href="http://www.math.columbia.edu/~woit/wordpress/?p=9180">here</a>). Each time it turned out that, the way the publishing process was going, I ended up having more time to work on the manuscript and deciding I could do better, especially with some of the basic material about quantum field theory. I do think the latest version has a much improved treatment of the basics of that subject.</p>
<p>This version will go off to Springer in a day or so, and they plan to publish it late this year/early next year. I’m setting up a <a href="http://www.math.columbia.edu/~woit/QMbook">web-page for the book</a>, there may be more material there later.</p>
<p>One thing ensuring that I will stop working on this is that in a couple days I’m heading off on vacation, for a two-week or so trip to Europe. Blogging during that time is likely to be light to non-existent. Back around the Fourth of July, and looking forward to thinking about other projects, anything but this book…</p>
Thu, 15 Jun 2017 01:37:53 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9395The Dangerous Irrelevance of String Theory
http://www.math.columbia.edu/~woit/wordpress/?p=9375
<p>Eva Silverstein has a new preprint out, entitled <a href="https://arxiv.org/abs/1706.02790">The Dangerous Irrelevance of String Theory</a>. The title is I guess intended to be playful, not referring to its accurate description of the current state of string theory, but to the possibility of irrelevant operators having observable effects. </p>
<p>The article is intended to appear in the forthcoming Cambridge University Press volume of contributions to the Munich <a href="http://www.whytrustatheory2015.philosophie.uni-muenchen.de/index.html">“Why Trust a Theory?” conference</a> held back in December 2015. The impetus behind that conference was a December 2014 article in Nature entitled <a href="http://www.nature.com/news/scientific-method-defend-the-integrity-of-physics-1.16535">Scientific method: Defend the integrity of physics</a>. In that article, Ellis and Silk explained the problems with string theory and with the multiverse/string theory landscape.</p>
<p>The organizing committee for the Munich conference was chaired by Richard Dawid, a string theorist turned philosopher who has written a 2013 book, <a href="http://www.math.columbia.edu/~woit/wordpress/?p=5880">String Theory and the Scientific Method</a>. For a fuller discussion of that book, see the linked blog post. To oversimplify, it makes the case that the proper way to react to string theory unification’s failure according to the conventional understanding of the scientific method is to change our understanding of the scientific method. Much of the Munich conference was devoted to discussing that as an issue in philosophy of science.</p>
<p>One aspect of the Munich conference was that it was heavily weighted towards string theorists, with contributions from Dawid, David Gross, Joe Polchinski, Fernando Quevedo, Dieter Lust and Gordon Kane all promoting the idea that string theory was a success. Polchinski explained a computation that shows that string theory is 98.5% likely to be correct, going on to claim that the probability is actually higher: “something over 3 sigma” (i.e. over 99.7%). The only contribution from a physicist that I’ve seen that argued the case for the failure of string theory was that from Carlo Rovelli, see <a href="https://arxiv.org/abs/1609.01966">here</a>. Silverstein’s article says that it was commissioned by Dawid for the proceedings volume, even though she hadn’t been at the meeting. I’m curious whether Dawid commissioned any contributions from string theory critics who weren’t at the meeting.</p>
<p>Silverstein begins her article explaining how physics at a very high energy scale can in principle have observable effects. This of course is true, but the problem with string theory is that, in its landscape version, it has a hugely complicated and poorly understood high energy scale behavior, seemingly capable of producing a very wide range of possible observable effects, none of which have been seen. The article is structured as a defense of string theory, without explaining at all what the criticisms of string theory actually are. The list of references includes 53 items, only one critical of string theory, the Ellis/Silk Nature article. Some of the arguments she makes are:</p>
<ul>
<li>
<blockquote><p>It is sometimes said that theory has strayed too far from experiment/observation. Historically, there are classic cases with long time delays between theory and experiment – Maxwell’s and Einstein’s waves being prime examples, at 25 and 100 years respectively… One thing that is certainly irrelevant to these questions is the human lifespan. Arguments of the sort ‘after X number of years, string theory failed to produce Y result’ are vacuous.</p></blockquote>
<p>I think the comparison to EM or GR is pretty much absurd. For one thing it’s comparing two completely different things: tests of a particular prediction of a theory (EM or GR) that made lots of other testable, confirmed predictions to the case of string theory, where there are no predictions at all. More relevant to the argument over how long to wait for an idea to pay off is that the real question is not the absolute value of the amount of progress, but the derivative: as you study the idea more carefully, do you get closer to testable progress or farther away? I don’t think anybody can serious claim that, 33 years on, we’re closer to a successful string theory unification proposal than we were at the start, back in 1985. I’d argue that the situation is the complete opposite: we have been steadily moving away from such success (and thus entered the realm of failure).
</li>
<li>About supersymmetry Silverstein writes:<br />
<blockquote><p>In my view, the role of supersymmetry is chronically over-emphasized in the field, and hence understandably also in the article by Ellis and Silk. The possibility of supersymmetry in nature is very interesting since it could stabilize the electroweak hierarchy, and extended supersymmetry enables controlled extrapolation to strong coupling in appropriate circumstances. Neither of these facts implies that low-energy supersymmetry is phenomenologically favored in string theory.</p></blockquote>
<p>It is true that Silverstein has never been one of those arguing that the usual string theory scenarios with supersymmetry and 10 or 11 dimensions show that string theory is testable. See for instance her comment <a href="http://www.preposterousuniverse.com/blog/2006/02/04/why-10-or-11/#comment-11331">here</a> back during a “String Wars” discussion in 2006. Her current take on whether string theory implies supersymmetry is just</p>
<blockquote><p>Much further research, both conceptual and technical, is required to obtain an accurate assessment of the dominant contributions to the string landscape.</p></blockquote>
<p>The problem with this is that there so sign of any possibility of progress towards deciding if the string theory landscape implies low-energy SUSY or not (quite the opposite). If you give up the assumptions of SUSY and 10/11 dimensions, you give up what little hope you had of any connection with experiment. She doesn’t mention the LHC at all, especially not the negative results about supersymmetry and extra dimensions that it has produced. The significance of these negative results is not that they disconfirm a strong prediction of string theory, but that they pull the plug on the last remaining hope for connecting standard string theory unification scenarios to anything observable. Pre-LHC string theorists could make an argument that there was good reason to believe in electroweak-scale SUSY, that such a scenario fit in well with string theory unification, and that LHC discovery of SUSY would point a way forward for string theory unification. That argument is now dead. All that’s left is basically the argument that “maybe a miracle will happen and we’ll be vindicated” which in her version is:</p>
<blockquote><p> In principle one could test string theory locally. In practice, this would require discovering a smoking gun signature (such as a low string scale at colliders, or perhaps a very distinctive pattern of primordial perturbations in cosmology), and nothing particularly favors such scenarios currently. </p></blockquote>
</li>
<li>Silverstein’s main argument is basically that string theory is valuable because it leads to the study of models that have various observable signatures that people would not otherwise look for. One example here is supersymmetry, the study of which has had a huge effect on collider physics, strongly shaping the analyses that the experimentalist perform. She gives some detailed other examples from her field of cosmology, in particular about possibly observable non-Gaussianities.<br />
<blockquote><p>String theory participates in empirical science in several ways. In the context of early universe cosmology, on which we have focused in this article, it helped motivate the discovery and development of mechanisms for dark energy and inflation consistent with the mathematical structure of string theory and various thought-experimental constraints. Some of these basic mechanisms had not been considered at all outside of string theory, and some not quite in the form they take there, with implications for effective field theory and data analysis that go well beyond their specifics.</p></blockquote>
<p>I think this is the best argument to be made for “phenomenological” string theory research (as opposed to “formal” string theory, where there are other arguments). Yes, coming up with new models with unexpected observable effects is a valuable enterprise. If your speculative idea generates such things, that’s well and good. The problem though is how to evaluate the situation of a speculative idea that has generated a huge number of such models, none of which has worked out. At what point do you decide that this is an unpromising line of research, better to try just about anything else? Silverstein makes the argument that</p>
<blockquote><p>Whether empirical or mathematical, constraints on interesting regions of theory space is valuable science. In this note we focus on string theory’s role in the former.</p>
<p>Since information theory is currently all the rage, it occurred to me that we can phrase this in that language. Information is maximized when the probabilities are equal for a set of outcomes, since one learns the most from a measurement in that case. The existence of multiple consistent theoretical possibilities implies greater information content in the measurements. Therefore, theoretical research establishing this (or constraining the possibilities) is directly relevant to the question of what and how much is learned from data. In certain areas, string theory plays a direct role in this process.</p></blockquote>
<p>The problem here is that of what is an “interesting region of theory space”. At this point the failures of string theory unification strongly indicate that it’s not such an interesting region. It seems likely that we’d be better off if most theorists focusing on phenomenology of this failed program were to pick something else to work on.</li>
</ul>
Mon, 12 Jun 2017 18:40:54 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=93752018 US HEP Budget
http://www.math.columbia.edu/~woit/wordpress/?p=9361
<p>HEPAP has been meeting the past couple days, with presentations available <a href="https://science.energy.gov/hep/hepap/meetings/201706/">here</a>. Much of the discussion is about the President’s 2018 budget proposal recently submitted to Congress, which contains drastic cuts to all sorts of programs, including for support of scientific research. In particular the proposal is to cut the total NSF budget from \$7.5 billion to \$6.65 billion (-11.3%), and the DOE science budget from \$5.4 billion to \$4.47 billion (-17%).</p>
<p>At the DOE, for HEP physics, the cut would be from \$825 million to \$673 million (-18.5%). For topics less popular with the new administration the cuts are even larger, e.g. a 43% cut for biological and environmental research. </p>
<p>At the NSF (numbers with respect to FY 2016), the proposed cut for DMS (Mathematics) is 10.3%, for Physics 8.5% (-\$23.6 million) and for Astronomy 10.3%. The FY 2016 budget number for Physics was \$277 million, of which \$13.2 million went to HEP theory.</p>
<p>Budget cuts on this scale would be extreme and unheard of, requiring shutting down major planned experimental projects. For some sorts of spending, this sort of cut is painful but manageable, but cutting out 18.5% of the spending on an experimental apparatus under construction may likely mean you don’t have an experiment anymore.<br />
The HEPAP presentations are from people working for DOE/NSF and under orders to plan for these cuts and not complain about them, so I think don’t reflect at all what the real implications of such cuts would be. </p>
<p>There’s a summary of discussion <a href="https://science.energy.gov/~/media/hep/hepap/pdf/201706/Lankford-Day2.pdf">here</a>, including a discussion of last year’s <a href="http://www.math.columbia.edu/~woit/wordpress/?p=8998">HEP theory letter</a>. It sounds like nothing much has been done about that, and it may not get much attention given the current situation.</p>
<p>It’s important though to keep in mind that this budget proposal may very well already be dead on arrival at Congress. Take a look at slide 22 of <a href="https://science.energy.gov/~/media/hep/hepap/pdf/201706/lsuter_communication_activites.pdf">this presentation</a> that reports that of the staffers and representatives asked about (a preliminary version of) this, only 8.4% were in favor. In recent years the US budgeting process has been quite dysfunctional, with actual budget numbers only appearing at the last minute of an opaque process leading not to a budget but to a “Continuing Resolution”. I doubt anyone has any idea what is going to happen this year, with the passing of something close to this budget probably one of the least likely eventualities. Physicists and mathematicians up in arms about these proposed budget cuts need to keep in mind the context: this budget is an extremely radical proposal of an unparalleled sort, with even larger cuts aimed at groups that are far needier than scientists (for one random example, food stamps are to be cut by 25.3%). Yes, scientists should be organizing to fight this budget, but the impacts on them and their research are one of the less important reasons for doing so.</p>
<p>I’m setting all comments to go to moderation. If you just want to rant pro or con about the awful situation the US is now in, please do it elsewhere. If you have any actual information about the effects of this on the physics and math communities as the budget process gets underway, that would be worthwhile and interesting. Two people tweeting about this are <a href="https://twitter.com/KyleCranmer/with_replies">Kyle Cranmer</a> and <a href="https://twitter.com/physicsmatt/with_replies">Matthew Buckley</a>.</p>
<p><strong>Updates</strong>: Details of the DOE HEP budget proposal are <a href="https://science.energy.gov/~/media/budget/pdf/sc-budget-request-to-congress/fy-2018/FY_2018_SC_HEP_Cong_Budget.pdf">here</a>. It explains that about 20-25% of the research positions funded by DOE at all levels would be eliminated. There would be an “extended shutdown of the Fermilab accelerator complex”.<br />
About 1/3 of DOE HEP theory funding would be eliminated, but it would be replaced by an equal amount of funding for quantum information science as a subfield of HEP. Looks like someone in the Trump administration is a great believer in “It From Qubit”…</p>
Tue, 06 Jun 2017 22:44:14 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9361Multiverse Politics
http://www.math.columbia.edu/~woit/wordpress/?p=9349
<p>The <a href="http://www.math.columbia.edu/~woit/wordpress/?p=9289">political campaign for the multiverse</a> continues today with a <a href="http://nautil.us/issue/48/chaos/the-inflated-debate-over-cosmic-inflation">piece by Amanda Gefter at Nautilus</a>. It’s a full-throated salvo from the Linde-Guth side of the multiverse propaganda war they are now waging, with Linde dismissing Steinhardt’s criticism as based on “a total ignorance of what is going on”. All of the quotes for the article are on the pro-multiverse side. There is a new argument from them I’d never heard before: Guth comes up with this one:</p>
<blockquote><p>You can create a universe from nothing—you can create infinite universes from nothing—as long as they all add up to nothing. Not only is that a deep insight, it also creates a testable prediction. “Eternal inflation certainly predicts that the average density of all conserved quantities should be zero,” Guth says. “So if we ever became convinced that the universe has a nonzero density of electric charge or angular momentum, eternal inflation would no longer be an option.”</p></blockquote>
<p>The article is subtitled “Why the majority of physicists are on one side of a recent exchange of letters”. One way to interpret this claim is just that 33 is more than 3, but the reason for this is clear: while Guth, Kaiser, Linde and Nomura decided to go on a political campaign, drumming up signatures on their letter, Ijjas, Loeb and Steinhardt didn’t do this, but instead put together a <a href="http://physics.princeton.edu/~cosmo/sciam/">website discussing the scientific issues</a>.</p>
<p>Where the majority of physicists stand on the Guth-Linde claims is an interesting question, one that I don’t think is addressed anywhere by hard numbers. My anecdotal data is that the majority of those I’ve ever talked to about this don’t think the Guth-Linde multiverse claims are science, but don’t see any reason to waste their time arguing with pseudo-science. They hope it will just go away by itself, as it becomes ever clearer that the multiverse is, scientifically, an empty idea.</p>
<p>Unfortunately, I don’t see this going away and I think it’s now doing very serious damage to physics and its public image. There’s a political campaign now being waged, and one side is very determined to win and putting a lot of energy into doing so. Those on the other side need to step up and make themselves heard. </p>
Thu, 01 Jun 2017 15:12:52 GMThttp://www.math.columbia.edu/~woit/wordpress/?p=9349