Various and Sundry

Posted on January 13, 2017 by woit

A few links for your weekend reading:

  • If you just can’t get enough of the Multiverse, Inference has commentary on Max Tegmark from Daniel Kleitman and Sheldon Glashow.
  • Coverage of the important topic of blackboards is to be found here. To those ill-informed sorts who think that blackboards are the past, whiteboards or some other technology the future, I’ll point out the following. When I came to Columbia back in 1989, there was a recently installed modest-sized whiteboard in the math department common room. Everyone hated it, and after many years it was replaced by a similar-sized blackboard. Last year, in a renovation of the lounge, that blackboard was replaced by a better one, and one whole wall of the room was replaced by a floor-to-ceiling blackboard. A year or so ago, a newly renovated Theory Center was unveiled here in the Physics department: floor-to-ceiling, wall-to-wall blackboards. That’s the future, the whiteboard is the past.
  • The latest CERN Courier has a long article by Hermann Nicolai, mostly about quantum gravity. Nicolai makes the following interesting comments about supersymmetry and unification:

    To the great disappointment of many, experimental searches at the LHC so far have found no evidence for the superpartners predicted by N = 1 supersymmetry. However, there is no reason to give up on the idea of supersymmetry as such, since the refutation of low-energy supersymmetry would only mean that the most simple-minded way of implementing this idea does not work. Indeed, the initial excitement about supersymmetry in the 1970s had nothing to do with the hierarchy problem, but rather because it offered a way to circumvent the so-called Coleman–Mandula no-go theorem – a beautiful possibility that is precisely not realised by the models currently being tested at the LHC.

    In fact, the reduplication of internal quantum numbers predicted by N = 1 supersymmetry is avoided in theories with extended (N > 1) supersymmetry. Among all supersymmetric theories, maximal N = 8 supergravity stands out as the most symmetric. Its status with regard to perturbative finiteness is still unclear, although recent work has revealed amazing and unexpected cancellations. However, there is one very strange agreement between this theory and observation, first emphasised by Gell-Mann: the number of spin-1/2 fermions remaining after complete breaking of supersymmetry is 48 = 3 × 16, equal to the number of quarks and leptons (including right-handed neutrinos) in three generations (see “The many lives of supergravity”). To go beyond the partial matching of quantum numbers achieved so far will, however, require some completely new insights, especially concerning the emergence of chiral gauge interactions.

    I think this is an interesting perspective on the main problem with supersymmetry, which I’d summarize as follows. In N=1 SUSY you can get a chiral theory like the SM, but if you get the SM this way, you predict for every SM particle a new particle with the exact same charges (behavior under internal symmetry transformation), but spin differing by 1/2. This is in radical disagreement with experiment. What you’d really like is to use SUSY to say something about internal symmetry, and this is what you can do in principle with higher values of N. The problem is that you don’t really know how to get a chiral theory this way. That may be a much more fruitful problem to focus on than the supposed hierarchy problem.

  • Progress in geometric Langlands marches on, with a new paper yesterday from Aganagic, Frenkel and Okounkov on the Quantum q-Langlands Correspondence, a two-parameter generalization of geometric Langlands. Among many other things, they formulate (Conjecture 6.3) a conjecture generalizing the characterization (using BRST methods) of affine Lie algebra representations at the critical level that from the beginning of the subject described a major aspect of how geometric Langlands works locally (for details on this, see Frenkel’s book Langlands Correspndence for Loop Groups).
Posted in Uncategorized | 59 Comments

New Year’s Multiverse

Posted on January 7, 2017 by woit

I see little to be hopeful about the new year, but had a glimmer of a hope that we’ll see a reduction in Multiverse Mania. Surely people will sooner or later get tired of stale pseudo-science. Just got back to work from vacation and it seems that so far this is not working out at all, quite the opposite.

At the yearly Edge question site, Martin Rees’s answer to the question “What scientific term or concept ought to be more widely known?” is The Multiverse, and he starts out with the usual sort of breathless hype:

An astonishing concept has entered mainstream cosmological thought…

Critics of the multiverse are described as having two arguments:

  • “Some claim that unobservable entities aren’t part of science.”
  • “Some physicists don’t like the multiverse: they’d be disappointed if some of the key numbers they are trying to explain turn out to be mere environmental contingencies governing our local space-time patch—no more truly “fundamental” than the parameters of the Earth’s orbit round the Sun.”

The first of these is the usual straw man argument, painting multiverse critics as too ignorant to realize that much of science is based upon indirect evidence, not direct observation. The actual argument of this sort against the multiverse is not that we can’t get direct evidence for it, but that there is no evidence of any kind for it, direct or indirect, and no plausible prospects of getting any. This case has been made ad nauseam here on this blog.

The second of these arguments is treated in much more detail in a new article at Nautilus by string theorist Tasneem Zehra Husain with the title Even Physicists Find the Multiverse Faintly Disturbing. Husain treats in detail the question of how physicists “feel” about the multiverse, and like Rees, makes the point that what physicists don’t “like” about the multiverse is that it removes hopes of being able to do things like understand the nature and strengths of fundamental forces, or calculate the masses of elementary particles.

Rees tells us that physicists are wrong to feel this way, that instead they should be awed by “the revelation that physical reality was grander and richer than hitherto envisioned” and that “If we’re in a multiverse, it would imply a fourth and grandest Copernican revolution.” Husain in the end seems to agree, quoting Gian Giudice:

Perhaps we need to let go of something we’re holding onto too tightly. Maybe we need to think bigger, refocus, regroup, reframe our questions to nature. The multiverse, he says, could open up “extremely satisfying, gratifying, and mind-opening possibilities.”

Of all the pro-multiverse arguments I heard, this is the one that appeals to me the most. In every scenario, for every physical system, we can pose infinitely many questions. We try to strip a problem back to the essentials and ask the most basic questions, but our intuition is built upon what came before, and it is entirely possible that we are drawing upon paradigms that are no longer relevant for the new realms we are trying to probe.

The multiverse is less like a closed door and more like a key. To me, the word is now tinged with promise and fraught with possibility. It seems no more wasteful than a bower full of roses.

Rees and Husain do a good job of showing that if science is about feelings, then Multiverse fans have a fine argument against critics arguing based on their negative feelings. The problem of course is that science is not about feelings but about evidence. The argument by critics that needs to be addressed is that there is no evidence at all for current multiverse scenarios, and no plausible way of getting any by scientific methods.

Nautilus has another multiverse-related piece just out, We Have Pushed Physics Too Far, by Marcelo Gleiser. My reading of the piece is that Gleiser agrees that the Multiverse is not successful science (“Parallel universes are a non-answer”), and I believe most physicists also agree. Unfortunately the lessons he draws from this (as I’m afraid many others are doing) is that the problem not a particular research program that failed (string theory, by ending up with the string landscape and the multiverse), but the whole idea of pursuing mathematical ideas about further unification:

We can call this the ultimate Platonic dream, the quest for a single simple and broad-ranging theory of physics. Indeed, during the past four decades, the search for such a theory has inspired many of the brightest physicists in the world. But today we are seeing the limits of this Platonic thrust to mathematize nature, due to a lack of experimental validation and several theoretical obstacles—including the possibility of multiple universes and the troubling questions they pose.

Gleiser sees successful physics as “an expression of intellectual humility”, with our current problem that of Icarus, trying to fly too close to the sun. I strongly disagree with him about this, seeing some of the best of physics as an expression of intellectual arrogance, not humility. It is intellectual arrogance that has gotten our understanding of nature as far as it has gone, and it will require intellectual arrogance to go farther. The current problem of theoretical physics is due not the sin of arrogance, but to a somewhat different one, that of refusing to admit error. Multiverse mania is largely about the refusal to admit that string theory unification is a failed idea. Yes, arrogance is one reason for this refusal, and admitting failure takes some humility. But then moving on to find different, more successful ideas will require a lot of both mathematics and intellectual arrogance.

Update: One more article at Nautilus about the multiverse. At least this one is explicitly theology, it explains:

a section of liturgy recited whenever we take the Torah out of the ark, and it’s related to a prayer that many Jews know, “Adon Olam.” The phrase is usually translated as “Sovereign of the Universe,” where the word olam can mean both “the universe” and “eternity,” expressing tremendous expanses of both space and time. But in this particular section of the Torah service, God is called “Adon Olamim,” where the suffix -im makes the word plural. This means that God is “Sovereign of the Universes,” as in, “more than one universe.” God doesn’t need to be a designer who had a specific plan in mind that led to the creation of humanity. God is, in fact, the Sovereign over all the universes, including the ones that don’t have life in them.

Update: Yet more explicit theological coverage of the Multiverse at science magazine Nautilus, with an article from Mary-Jane Rubinstein, a professor of religion, who is interested in multiverse versions of pantheism and explains:

As a professor of religious studies, I am particularly drawn to the places where religion and science seem antagonistic, but turn out to be entwined. The multiverse, I would argue, is one of those places.

My only disagreement here would be whether being a place where science and religion are intertwined is a good or bad thing…

Update: Yet more in the Nautilus series on the Multiverse: more theology, and now teleology.

Update: In case you were worried that Multiverse pseudo-science was incompatible with the Quran, have no fear.

Update: 2017 is well on its way to a bumper crop of Multiverse Mania. Today it’s New Scientist’s turn.

Update: This crap is just endless, more every day. Today it’s at Astronomy Magazine, about this nonsense, debunked long ago by Jennifer Ouellette.

Posted in Multiverse Mania | 73 Comments

What Graduate School in Theoretical Physics is Really Like

Posted on December 29, 2016 by woit

I’m about to head off for a short New Year’s vacation in West Texas, but wanted to recommend a wonderful article that just appeared at Nautilus. It’s a memoir by Bob Henderson (who I met when he wrote about me, see here), appearing under the title What Does Any of This Have To Do with Physics? (although the title of the web-page, What Graduate School in Theoretical Physics is Really Like, is more descriptive).

Henderson was a graduate student at Rochester in theoretical physics, working with S.G. Rajeev. He later went to work on Wall Street, and more recently in journalism. His Nautilus piece is the best explanation I’ve ever seen of what it’s like to start working in this field as a graduate student, should certainly be required reading for anyone thinking of going into the subject. It’s also somewhat of a profile of Rajeev, who has worked on a wide variety of topics in theoretical physics.

One of the main themes of the piece is Henderson’s thinking about how and why he left theoretical physics, why he “quit”. Something to keep in mind is that this kind of decision is what most people who get Ph.Ds in the subject end up facing. There are 5-10 times more people getting Ph.Ds in this field than there are permanent positions doing research in it, so the career path starts out with a game of musical chairs that you are highly likely to lose. Different people make the choice to quit the game and do something else at different points and in different ways.

Henderson does an excellent job also of explaining what the real problem is with doing this kind of research: that of figuring out what the right thing to calculate is. For everyone, but especially for those at the beginning of a career, the subject is a huge collections of topics one doesn’t understand. One has to somehow choose a direction to pursue, and it most likely won’t go anywhere:

Writers talk of the terror of facing a blank page, but it’s no different for theorists like Rajeev trying to choose which path to take. There are an infinite number to choose from, and most go nowhere or back from where you came. The clock is always ticking and you spend so much time in the dark that it can make you not only question your path, but your own self worth. It can make you feel stupid.

Sticking with this and making a career of it involve some combination of good luck (being in the right place at the right time), ability, self-confidence, not having a family to support, and a host of other factors. As Rajeev explains to him:

Without naming names, he ticked through a catalog of his contemporaries who’d succeeded in theoretical physics even without having the towering mathematical intellect that I was sure it took and that Rajeev surely has. They’d made it, Rajeev explained, by focusing on problems that played to their strengths, or by taking advantage of computers, or by collaborating with peers who had complementary skills. Some socially gifted but not so mathematically talented types had gone quite far this way, earned a lot of renown.

Anyway, the whole piece is well-worth reading. Another recently published Nautilus piece that I learned about from a link on this one is The Universes of a Woman in Science. It’s by Kate Marvel, who shares with Henderson (and hundreds if not thousands of others…) the experience of getting a theoretical physics Ph. D. (string cosmology in her case), and then leaving the subject for another field (in her case, climate science, which she blogs about here).

Posted in Uncategorized | 47 Comments

Various Links

Posted on December 15, 2016 by woit

A grab-bag of unrelated topics and links:

  • Continuing the subject of budget cuts from the last posting, I heard today that the NSA is not funding this year the grant program that the AMS has been running for it, called the NSA Mathematical Sciences Program. In typical NSA fashion, no real reason given:

    after much deliberation our senior management has decided that the MSP will not have the resources to make new awards in FY2017.

    Even less information is available than in the case of the similarly mysterious DOE HEP Theory cuts, since all information about the NSA budget, even the total, is classified (although from Snowden and others, it seems that it’s about $10.5 billion).

  • The IHES has a new website.
  • This spring Peter Scholze will give a series of six lectures at the IHES on the latest about the local Langlands conjectures.
  • Via David Roberts, the LMS has some videos about mathematicians here. Kevin Buzzard explains Langlands:

    The Langlands philosophy? Yeah, that’s like Birch-Swinnerton-Dyer on crack, isn’t it?.

  • Tate’s collected works are finally available from the AMS.
  • Turning to physics, there’s a very good new article at Quanta from Natalie Wolchover about the unsuccessful search for proton decay and what this means for grand unification ideas. Glashow has now given up, with the simplest GUTs now conclusively ruled out:

    Glashow, for one, largely lost interest in the whole affair when SU(5) was ruled out. “Proton decay has been a failure,” he said. “So many great ideas have died.”

    Not everyone has given up though, with fans of the “flipped SU(5)” SUSY GUT explaining things this way:

    Barr, one of the originators of the still-viable “flipped SU(5)” GUT model, compared the situation to waiting for your spouse to come home. “If they’re 10 minutes late, there’s simple explanations for that. An hour late, maybe those explanations become a little less plausible. If they’re eight hours late … you begin to worry that maybe your husband or wife is dead. So the point is, at what point do you say your theory is dead?”

    Right now, he said, “we’re more at the point where the spouse is 10 minutes late, or maybe an hour late. It’s still completely plausible that grand unification is correct.”

    Besides the current wishful thinking, this particular model has a strange history. You can read here about how it follows from Vedic Science. Over the years it has been about to come home many times, see this from 2012, which assures us that:

    The CMS and ATLAS experiments have also observed tantalizing hints of the unique signature predicted by the Flipped SU(5) model.

    At this point, it seems to me to be way more than an hour late, time for its nearest and dearest to admit that it’s dead (or maybe has run off with its TM instructor).

  • Also in Quanta, you can read about Janet Conrad and sterile neutrinos here.
  • I don’t always agree with Sabine Hossenfelder about math, but I very much agree with the conclusion of this posting:

    In lack of experimental guidance, what we need in the foundations of physics is conceptual clarity. We need rigorous math, not claims to experience, intuition, and aesthetic appeal. Don’t be afraid, but we need more math.

  • There’s a Recent Developments in Fields, Strings, and Gravity conference going on this week at the new Center for Quantum Mathematics and Physics at Davis.
  • Videos of the talks at the recent John Schwarz 75th birthday conference at Caltech are available here.
  • Multiversal Journeys is an organization devoted to promoting theoretical physics, with a heavy dose of multiverse mania as part of their story. They have a new book coming out, Quantum Physics, Mini Black Holes and the Multiverse, supposedly “Debunking Common Misconceptions in Theoretical Physics”. It seems that one of these common misconceptions is that the multiverse is pseudo-science. To fight this, they’ve also produced a promotional video.
  • Bert Schroer has an interesting preprint with a lot of material about Rudolf Haag and algebraic quantum field theory.
  • Another intriguing preprint recently out is from Arkani-Hamed and collaborators. In the past Arkani-Hamed has been vehement about gauge symmetry just being a worthless redundancy in our description of physics, for instance stating:

    What’s as a misnomer called gauge symmetry, whose beauty is extolled at length in all the textbooks on the subject, is completely garbage. It’s completely content free, there’s nothing to it.

    In the new paper, instead of gauge invariance being useless, there’s a conjecture that locality and unitarity, instead of being fundamental principles, follow from gauge invariance.

    There’s a long tradition in the philosophy of physics literature of arguing over whether gauge symmetry is a fundamental idea or a useless redundancy. I’m on “fundamental idea” side, but of course exactly what the role of gauge symmetry is in fundamental physics is something that we have yet to fully comprehend.

Posted in Langlands, Multiverse Mania, Uncategorized | 29 Comments

HEP Theory Letter

Posted on December 8, 2016 by woit

A couple weeks ago a large group of US HEP theorists wrote a letter to the DOE High Energy Physics Advisory Panel (HEPAP) (available at page 7 here) expressing alarm at trends in DOE funding of HEP theory, ending with

We formally request that a subpanel of HEPAP be formed to investigate and better understand this damaging trend and to make recommendations to address its consequences and restore a thriving Theory program, and we strongly urge that HEPAP support measure to rebuild and maintain the prominent and world-leading standing of US High Energy Theoretical Physics.

The letter claims that since 2011 the overall DOE HEP Theory program has been cut by 17%, with the university component of this cut by 30%. It also claims that 25% of DOE-supported university theorists have had their funding cut off in the last four years, with the number of postdocs going down by about 30%.

At last week’s HEPAP meeting there was a discussion of this, but I don’t know what was decided. Some numbers presented there indicated that from FY2013-2015. the DOE theory budget went from $51.2 million to $49.32 million. The net number of funded PIs was reduced by more than 10% (25 out of about 230), with 52 PIs dropped, 27 new ones coming in. The conclusion of that presentation was that “The theory program in its current state cannot be described as thriving.” The emphasis in the letter and this presentation on “thriving” is a reference to one of the P5 recommendations that is supposed to be governing how the DOE HEP budget is allocated:

The U.S. has leadership in diverse areas of theoretical research in particle physics. A thriving theory program is essential for both identifying new directions for the field and supporting the current experimental program.

The most detailed recent information I can find about the DOE HEP theory budget is in this presentation from August. It shows a decline from FY10 to FY16 from $53.09 million to $46.69 million, with most of this in the component going to university groups, which went from $27.25 million to $21.765 million. The current number of postdocs supported is listed as about 125 (100 at universities, 25 at the labs), the number of graduate students is about 120.

Concern about this decrease in funding first became public two and a half years ago (see my blog post here) with Sean Carroll’s blog post describing a “calamity”. Various HEPAP presentations warned physicists about the dangers of public complaints and these died down for a while, but the continuing cuts to the university component of theory funding seem to have led to the decision to send this new letter.

An odd part of this story is that it’s unclear why this decision to reduce DOE HEP theory university funding significantly was made. It’s true that the overall DOE HEP budget has been cut over the same period (from $810.5 million in FY10 to $795 million in FY16) but unknown why the university theory component was cut 20% over this period while the overall cut was only 2%. Note that none of these numbers are adjusted for inflation.

It would be very interesting to hear comments from anyone who knows more about what is going on here. The usual generic comments that government spending is bad will be deleted. Keep in mind that the amount of money at issue here is (2.7% of the HEP budget, .00058% of the total federal budget) very small on the scale of government funding of science, and now ever small on the scale of private science funding (the Simons Foundation alone last year gave out $233 million in grants).

Update: A full copy of the letter with all signatures is here. An explanation of where the numbers in the letter come from is here.

Posted in Uncategorized | 28 Comments

Anomaly!

Posted on December 6, 2016 by woit

Tommaso Dorigo’s new book Anomaly! Collider Physics and the Quest for New Phenomena at Fermilab has just become available. I highly recommend it to anyone with an interest in high energy physics who wants some insight into how collider experiments are done. Dorigo is a well-known blogger, with the best (as well as most entertaining) blog there is about the experimental side of high energy physics. If you’re not following his blogging, you should be.

The nominal topic of the book is research conducted at the Tevatron by the CDF experiment during the 80s and 90s, into the early 2000s. Some of the specific well-known CDF results discussed in detail include measurement of the Z mass and the discovery of the top quark. The material about the top quark discovery comes closest to the kind of thing you find in other books. It’s a very well-done insider’s account of the story of an important discovery. I don’t know of a better place to read about the top quark search and how it finally succeeded.

One of the most unusual aspects of the book, in evidence in the top quark section and throughout the rest, is that it goes much deeper into an explanation of how collider experiment physics analyses are actually done than is usual in a popular or semi-popular book. Besides the insider’s local color and insights into the personalities involved, there’s quite a bit of discussion of the technical issues of the subject. This is a subject involving thorny issues of how best to reconstruct the properties of particles coming out of collisions, and finding clever new ways to deal with these while avoiding subtle pitfalls is a central problem, one outsiders normally don’t get to hear about.

The other unusual aspect of the book is that it doesn’t just discuss success stories of striking discoveries (of which there hasn’t been much between the top and the much later Higgs discovery at the LHC). One of the main activities of the field has been the search for “anomalies”, experimental results that disagree with the Standard Model and point to new physics. The problem is that finding anomalies is common, but they almost certainly will turn out to be due to some problem with the experiment or its analysis (such problems are always much more likely than revolutionary new physics).

One of the stories of an anomaly described extensively is that of an excess of high transverse energy jets, something that one might expect to see if quarks had some substructure (“preons”). Here the problem turned out to have a lot to do not with the experimental result, but with the theoretical modeling of what to expect from QCD. Another example is the story of “superjets”, events involving a W and 2 or 3 jets, with unusual properties.

For the “superjets” and for other anomalies, a favorite explanation was to invoke supersymmetry, since supersymmetric models predict a large range of different kinds of new particles, and one might hope that any anomaly is due to one of them. Dorigo has a few stories about theorists I hadn’t heard, in particular that of a fall 1995 letter signed by many prominent theorists (except Howard Georgi, who refused to sign). Despite ongoing efforts to look for superpartners, all of which had been unsuccessful, the feeling of the theorists was that the Fermilab experimenters weren’t trying hard enough. The letter was sent to the Fermilab director as well as the CDF and DZERO spokespersons. It explained what a great idea supersymmetry was, and ended with

We, the undersigned, believe that Fermilab has unique detection possibilites for supersymmetry, and urge you to direct your laboratory’s efforts in that direction, and ask the leaders of the collider detector collaborations to intensify their search for massive superpartners.

For more than two decades now, such searches for superpartners have been one of the dominant activities of collider experiments, with well-known negative results.

Finally, another important and unusual theme that runs through the book is the question of how to statistically characterize the significance of an anomaly. This is a topic where Dorigo is very much an expert, recently heading the CMS Statistics Committee.

Anomaly! is both a great tale of how science is really done, and an unusually insightful exploration of the crucial question of how one evaluates the significance of hints of new experimental discoveries. This question is of central importance now as the LHC gathers and analyzes data in a previously unexplored energy range. There are undoubtedly anomalies galore being studied by the LHC scientists, almost all of which will never be heard of by the public, as the experiments cautiously work to eliminate every possible conventional physics explanation for the anomaly. The 750 GeV diphoton bump of the past year is one example of an anomaly that made it out to a public announcement, with its disappearance in this year’s data making clear why the experiments are so cautious. You can’t find out about these ongoing stories, perhaps for good reason, due to the policies of how collider experiments are run, but now you can buy a copy of Anomaly! and at least read about how things played out in the previous generation of such experiments. This background should be helpful to make sense of what is going on if and when (March?), the next LHC anomaly gets reported.

Posted in Book Reviews | 5 Comments

Breakthrough Prizes 2017

Posted on December 4, 2016 by woit

The 2017 Breakthrough Prizes have just been announced, here are the winners and a few comments. Note that I’m leaving the usual singing of praise of the many virtues of the laureates to others, since there should soon be a lot of such stories appearing. Instead I’ll concentrate on issues that aren’t getting as much attention.

Already announced back in May, there is a special Breakthrough Prize for the LIGO collaboration: \$1 million to be split by Drever, Thorne and Weiss, \$2 million to be split by the other 1012 members of the LIGO collaboration. Quite likely Drever, Thorne and Weiss will get the Nobel Prize next year (the LIGO result was published too late for consideration this year). A very good thing about the Breakthrough Prize though is that it is given to the entire collaboration, with awards going to every one. They have done similar things in the past, with awards to the LHC experiments, to neutrino experiments and to the accelerating universe supernova experiments.

The Nobel Prize in Physics and most other such prizes are never awarded to a group, just (at most three) individuals. In an era of large scientific collaborations this isn’t fair, with all the recognition and prize money going to some small set of people, nothing to anyone else. I’m glad to see that, for these experimental prizes, the Breakthrough Prize has been following a different model.

The 2017 \$3 million Breakthrough Prize in mathematics goes to Jean Bourgain of the Institute for Advanced Study in Princeton. I’m not particularly familiar with his work, you’ll have to read about it elsewhere. He is a well-known figure in the math community, already a recipient of many prizes including the Fields Medal, Shaw and Crafoord prizes.

I’ve never been convinced that this mathematics $3 million prize is a good idea, since it typically goes to someone like Bourgain who, besides being an essentially randomly chosen lucky winner from a sizable pool of similarly distinguished mathematicians, already has prize money and a very well paid position with minimal responsibilities. This isn’t going to help him do better mathematics. A much better way to spend the money would be on endowing new permanent academic positions in mathematics, allowing more talented young people to have a career in mathematical research.

The philosophy behind the Breakthrough Prizes, very visible in the glitzy award ceremony (you can watch it on the National Geographic channel this evening, 10pm EST), is that scientists don’t get the kind of fame and stardom they deserve, so Milner and Zuckerberg are going to help fix this. What motivates good mathematics though is something very different, and bringing to mathematics more of the Hollywood star system is not going to improve mathematics research. In recent decades much of US society has moved to a brutal winner-take-all system. While our Silicon Valley overlords have flourished under this, I don’t think their bringing more of it to scientific research is a good idea.

While one can argue that the huge checks to mathematicians don’t have any particular negative effect, the situation in theoretical physics is quite different. Since the original laureates chosen by Milner, the yearly prizes that have gone to theorists (as opposed to the experimental prizes mentioned above) have all gone to string theorists (there was also a special prize given to Hawking). First there was Polyakov, then Green and Schwarz, and this year the $3 million Breakthrough Prize in Physics goes to three more string theorists: Joe Polchinski, Andy Strominger, and Cumrun Vafa.

In the case of string theory, I don’t think one can seriously argue that the field suffers from a lack of public attention. Mountains of hype about string theory have been produced in the last 32 years, seriously damaging the field of theoretical physics. This year’s prize adds to that mountain, with hype-ridden citations [press materials] backing the glitzy ceremony and million dollar checks. The language tries to turn physics research Hollywood: for instance, relativity and quantum theory are “the two superstar theories of modern physics”.

Perhaps the worst aspect of these prizes and citations [associated explanatory materials] is that they often hype and reward failed theoretical ideas: if your ideas work maybe you’ll get part of a \$1 million Nobel Prize, but if they fail, as long as they’re about string theory, you’ll get part of a \$3 million Breakthrough Prize. The citation [description of “Contributions”] for Strominger includes this about string theory:

Andrew Strominger played a major role in its emergence when he showed that it not only reconciles quantum mechanics with gravity, but can also contains within it the other observed particles and forces.

This refers to Strominger’s early work on Calabi-Yau compactifications, while not mentioning that this idea has never worked out.

These prizes are often awarded for ideas about the black hole information paradox, independent of whether these ideas work. Maldacena’s citation from 2012 tells us that he got the award partly for “resolving the black hole information paradox”, and the Strominger citation [description of “Contributions”] tells us that “His work hints at a solution to the famous ‘black hole information paradox’”. Polchinski is rewarded for a

big idea, deriving from the principles of quantum mechanics: ‘firewalls’ –blizzards of high-energy particles around black holes. The existence of firewalls would signal a fault line in the foundations of physics: at least one of the two superstar theories of modern physics – relativity theory and quantum theory – would have to be incomplete at a fundamental level.

Anyone reading this is unlikely to figure out that the significance of Polchinski’s “big idea” is that it purports to show that the solution to the paradox supposedly given by Maldacena actually doesn’t work (not surprising, since it was never more than a speculation). If you’re a string theorist, you don’t actually need to solve a problem to get a prize: speculation about what the solution to a problem might be is good enough, as is finding problems with the speculations of other string theorists. This sort of thing does nothing to improve the difficult situation of current theoretical physics, quite the opposite.

Tomorrow there will be a symposium at UCSF featuring 15 minute “TED-style” talks giving “pragmatic versions” of what could be done during the next ten years. For string theory, the blurb for the talk or talks is

Medium-term goals of string theory, from resolving the paradoxes of black holes to estimating the lifetime of the universe.

After a cycle of two prizes for resolving the information paradox and then unresolving it, I suppose it’s a reasonable goal for string theorists to go through another cycle or so during the next ten years. The idea of using string theory to “estimat[e] the lifetime of the universe” anytime soon goes beyond any of the usual hype, so we’ll have to see what that’s about tomorrow.

Update: Smaller \$100,000 “New Horizons” prizes, some split in various ways, went to 6 theoretical physicists (Asimina Arvanitaki, Peter Graham, Surjeet Rajendran, Simone Gombi, Xi Yin and Frans Pretorius) and 4 mathematicians (Mohammed Abouzaid, Hugo Duminil-Copin, Ben Elias and Geordie Williamson). Congratulations to all, especially to the Columbia contingent (Mohammed is a faculty member now, Ben was a grad student here, and TA one year for my representation theory course).

Update: Some of the language quoted above as part of the citations for the string theory awards was actually in a separate section of materials distributed to the press called “Contributions”, which gave more specifics of what the award was being made for. I’ve changed the wording above to more accurately reflect this.

Update: Just watched the Breakthrough Prize ceremony on TV. Very nice short portrait of Jean Bourgain and his work, and remarks by him. The string theorists were right at the end, and the DVR cut off in the middle of a clip of outrageous hype from them (I guess the ceremony went slightly longer than scheduled).

Update: Nature has coverage of the prizes here, emphasizing the award to Polchinski for firewalls, with some justification from Milner.

Update: Livestream of the symposium is here. Polchinski and Strominger will be talking about black hole information paradox/string theory, Vafa will describe “a research program for putting rigorous bounds on the lifetime of our universe, by studying the range of possibilities permitted by the laws of string theory.”

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Various Links

Posted on November 22, 2016 by woit

A few pre-Thanksgiving items:

  • International Journal of Modern Physics A has a new issue with “Featured Topic” part I of a discussion of the proposed Chinese supercollider project. The high profile contributions are from C. N. Yang, China should not build a supercollider at this time, and a response from David Gross: Why China should build the Great Collider. Both I think do a good job of making the case for and against the project, with the central question that of the high cost. If this was a $1 billion project there would be no question it would get done, and if it was a $100 billion project it could never happen. The problem is that the order of magnitude is $10 billion.

    There are some other contributions to the debate, including sensible pro-collider pieces by Yifang Wang and Weimin Wu. There’s also a bizarre piece by Henry Tye, making an ad hominem argument against Yang, based on the fact that in 1980 Yang was skeptical about the future of high energy physics. I’m afraid that this doesn’t work very well as an argument against Yang, whose prediction of no post-1980 breakthroughs looks unfortunately prescient these days.

  • According to the New York Times, one possibly imminent non-HEP breakthrough is a Microsoft quantum computer. Their project grew out of one they funded led by topologist Mike Freedman.
  • Last weekend there was a celebration at Caltech of John Schwarz’s 75th birthday. No slides or video of talks it seems. I’ve wondered what Susskind’s take on supersymmetry is these days, so curious what might have been in his talk entitled “Supersymmetry and the Limits of What We Know”.
  • Howard Burton was the founding director of Perimeter, helping to get it off the ground and turn it into the success it has become (Sabine Hossenfelder here notes that the term of the current director Neil Turok is up and wonders who is next). In recent years Burton has been running something he calls Ideas Roadshow, and now has a new blog called In Search of Refinement. He writes about a recent event with Roger Penrose, discussing his new book, and has kind things to say about my review of the book. Ideas Roadshow now has accumulated a significant number of interesting interviews, worth your while if you’re looking for high-quality but not free internet content to support.

Update: One more. Yet more private funding for US scientific research. The New York Times reports on the Simons Foundation Flatiron Institute, a planned $80 million/year, 200 employee research institute. The focus will be on computational work, and doing better science by freeing scientists from having to apply for grants.

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What Math Do You Need For Physics?

Posted on November 17, 2016 by woit

Chad Orzel has a very sensible piece at Forbes, headlined What Math Do You Need For Physics? It Depends, which addresses the question of what math a physicist like him (experimental AMO physics) really needs. I’m glad to see that he emphasizes the same basic courses my department offers aimed at non-majors:

  • Multivariable calculus
  • Differential equations
  • Linear algebra

together with statistics (which here at Columbia is handled by a separate department). He disses complex analysis, for reasons that I can understand. That’s a beautiful subject, and the results you can get out of analytic functions and contour integration are often unexpected and seemingly magic, but they’re not of as general use as the other subjects.

One subject he doesn’t mention that I would argue for is Fourier Analysis, which is the class I’ll be teaching next semester. That’s an incredibly useful as well as profound subject which every physicist should know, but it is true some of its basics often gets taught in other courses (for example in ode courses as a method for solving differential equations).

Orzel starts off with an amusing discussion of a physics version of “Humiliation”, admitting that he’s never used or really worked through a proof of Noether’s theorem, widely considered “the most profound idea in science”. I’ve argued here for the Hamiltonian over Lagrangian method, in which case a different set of ideas about symmetry is fundamental, with Noether’s theorem playing no role. In the Hamiltonian case symmetries are generated by functions on phase space, and finding the function that generates any symmetry is a matter of Poisson brackets (as an experimentalist, maybe Orzel has never calculated a Poisson bracket either though…).

One says that a function F on phase space generates an infinitesimal transformation if such an infinitesimal transformation changes the function G by {G,F} (the Poisson bracket of the functions G and F). A basic example is the Hamiltonian function, with {G,H} the infinitesimal change of G by time translation, or in other words, Hamilton’s equation
dG/dt={G,H}
When {H,F}=0, we say that the infinitesimal transformation generated by F is a symmetry, since H is left unchanged by such transformations. Using the antisymmetry of the Poisson bracket, this can also be read as {F,H}=0, with Hamilton’s equation then the conservation law that F doesn’t change with time.

All this seems to me much more straightforward than the Lagrangian Noether’s theorem approach to symmetry transformations and conservation laws. My own analog of Orzel’s admission would be admitting (which I won’t do) how long it took me in life to understand this fundamental point (I blame my teachers).

For lots and lots more about this, see chapters 14 and 15 here.

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String theory might be about to finally be killed off

Posted on November 13, 2016 by woit

News site TechEye is reporting that String theory might be about to finally be killed off, with a story that starts off

The world’s top boffins are debating finally killing off one of the more elegant scientific theories about the nature of reality.

This isn’t exactly the most reliable information source, with one problem that the story is about supersymmetry, with the only connection to string theory this:

For ages the world’s cleverest physicists have been divided over the concept of supersymmetry – a theory which stipulates that all known fundamental particles have heavier, supersymmetric counterparts called sparticles. It appears to be based on the theory that the universe is made out of string which was teased into shape by cats which are potentially dead or alive [are you sure about this? Ed.]

The writer seems to have gotten the material for the story from a more reliable source, the Economist, which recently had A bet about a cherished theory of physics may soon pay out. That story starts by explaining about Ken Lane’s 1994 bet with David Gross that the LHC would not see supersymmetry. As mentioned here, this year’s data should be enough to resolve the question they were betting about. It is likely that results from SUSY searches using most of this year’s data will be presented at the usual mid-December LHC Jamboree at CERN, and unless there’s dramatic news my sources are keeping from me, these results will be negative.

The bet was for an expensive dinner at Girardet’s, a three-star Swiss restaurant which has now closed, and

Dr Lane says it is time for Dr Gross (who won the Nobel prize in 2004) to cough up—if not with dinner at Girardet’s then at another suitably ritzy venue. After receiving no response to several e-mail prompts, however, Dr Lane is growing impatient. “David appears to be welshing [misuse of language, see here] on our bet,” he says.

but

Dr Gross is not ready to concede quite yet. The data are in, but their analysis is not complete. “It looks like I will lose this bet by the end of the year,” he says, “but we should await the word from the experimenters themselves.” (Dr Lane says the original terms have been met and Dr Gross should throw in the towel.)

As for whether this really kills off SUSY, there’s a pithy quote from Sabine Hossenfelder:

Sabine Hossenfelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies, is one of many who think it is time for theorists to focus on other problems—how gravity behaves at the very small scales of quantum mechanics, for instance. If the LHC finds no trace of sparticles in this year’s data, she believes the last thing the field needs is another round of Susy model adjustments. “That’s not science,” she says. “That’s pathetic.”

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