Still Not Even Wrong

Posted on September 24, 2016 by woit

A while back Tushna Commissariat of Physics World came to talk with me at Columbia, partly to discuss the topic of “Not Even Wrong, ten years later”, and that has now been turned into a podcast available as Still Not Even Wrong.

I’ve now forgotten what I said then, but presumably I still agree with it. This coming week I’m traveling and won’t have much time to deal with the blog, so comments from me may be few and far between.

Update: There’s an appreciative blog post about this here from ZapperZ.

Posted in Not Even Wrong: The Book | 11 Comments

Heidelberg Laureate Forum

Posted on September 19, 2016 by woit

This week I’m in Heidelberg, attending the Heidelberg Laureate Forum, where I’ll be writing some blog posts for their website (which should appear here). You can follow talks on their website, either in real-time as streaming video, or by watching a talk video later on.

This event brings together mathematicians and computer scientists. More specifically winners of the Fields Medal, Abel Prize, ACM Turing award and Nevanlinna Prize come to give talks and interact with a large group of young researchers (and various hangers-on such as myself).

Update: I wrote blog entries for the HLF about Faltings, Ngo, Wiles, Atiyah and Voevodsky. Now on my way to London, will spend the next week in England, mostly in Oxford.

Posted in Uncategorized | Comments Off on Heidelberg Laureate Forum

This Week’s Hype

Posted on September 15, 2016 by woit

Quanta Magazine has over the past couple years been establishing a well-deserved reputation as the smartest and best science journalism around. At the opposite extreme, over many years of interacting with science journalists, the most embarrassingly incompetent one I’ve run across has been KC Cole, so I was surprised today to see that Quanta has published a piece by her.

Back in 2006 she wrote a review for the LA Times, basically explaining that Lee Smolin and I shouldn’t be listened to because we were incompetent embittered failures who didn’t understand the beauties of string theory. When I contacted her and the LA Times to complain that her review had completely misrepresented what I wrote in my book about neutrino physics, she wrote back to explain to me that I didn’t know what I was talking about, whereas she was an expert on neutrino physics. Her other main evidence for my ignorance was this:

As for Woit’s claim that string theory has “absolutely zero connection with experiment,” experiments already planned for a new European particle accelerator will look for the existence of extra dimensions and extra families of particles — both predicted by string theory. In fact, many statements about string theory in these books are plain wrong.

The topic of her new article is The Strange Second Life of String Theory, which makes the claims that string theory has failed as a theory of quantum gravity (which will be news to a lot of string theorists), but that “it has blossomed into one of the most useful sets of tools in science.”

The article has all sorts of interesting quotes from experts about the state of string theory these days, mostly indicating that people have given up on it and are trying to figure out how to move on. For instance:

David Gross: “After a certain point in the early ’90s, people gave up on trying to connect to the real world,” Gross said. “The last 20 years have really been a great extension of theoretical tools, but very little progress on understanding what’s actually out there.”

Robbert Dijkgraaf: “But now we have this big mess.” “Things have gotten almost postmodern.”

“Nobody knows whether to say they’re a string theorist anymore,” said Chris Beem, a mathematical physicist at the University of Oxford. “It’s become very confusing.”

At last year’s big annual string theory meeting, the Stanford University string theorist Eva Silverstein was amused to find she was one of the few giving a talk “on string theory proper,” she said.

Juan Maldacena jokingly defines “string theory” as “Solid Theoretical Research in Natural Geometric Structures.”

Like many of his colleagues, [David] Simmons-Duffin says he’s a string theorist mostly in the sense that it’s become an umbrella term for anyone doing fundamental physics in underdeveloped corners. He’s currently focusing on a physical system that’s described by a conformal field theory but has nothing to do with strings.

I’m amused to hear that according to Maldacena and Simmons-Duffin, it appears that I’m a string theorist. One thing Cole gets right is that most theorists are now working on questions about quantum field theories. Sean Carroll objects to this:

It’s the kind of work that makes people such as Sean Carroll, a theoretical physicist at the California Institute of Technology, wonder if the field has strayed too far from its early ambitions — to find, if not a “theory of everything,” at least a theory of quantum gravity. “Answering deep questions about quantum gravity has not really happened,” he said. “They have all these hammers and they go looking for nails.” That’s fine, he said, even acknowledging that generations might be needed to develop a new theory of quantum gravity. “But it isn’t fine if you forget that, ultimately, your goal is describing the real world.”

It’s a question he has asked his friends. Why are they investigating detailed quantum field theories? “What’s the aspiration?” he asks. Their answers are logical, he says, but steps removed from developing a true description of our universe.

Instead, he’s looking for a way to “find gravity inside quantum mechanics.” A paper he recently wrote with colleagues claims to take steps toward just that. It does not involve string theory.

Cole tells us that

Like many a maturing beauty, string theory has gotten rich in relationships, complicated, hard to handle and widely influential. Its tentacles have reached so deeply into so many areas in theoretical physics, it’s become almost unrecognizable, even to string theorists.

According to her, string theory has made “essential contributions to cosmology” (this likely is news to cosmologists), especially by revealing the multiverse, which is now “taken for granted by a large number of physicists”, one of whom you might think is David Gross, since she writes:

Inflationary models get tangled in string theory in multiple ways, not least of which is the multiverse — the idea that ours is one of a perhaps infinite number of universes, each created by the same mechanism that begat our own. Between string theory and cosmology, the idea of an infinite landscape of possible universes became not just acceptable, but even taken for granted by a large number of physicists. The selection effect, Silverstein said, would be one quite natural explanation for why our world is the way it is: In a very different universe, we wouldn’t be here to tell the story.

This effect could be one answer to a big problem string theory was supposed to solve. As Gross put it: “What picks out this particular theory” — the Standard Model — from the “plethora of infinite possibilities?”

Silverstein thinks the selection effect is actually a good argument for string theory. The infinite landscape of possible universes can be directly linked to “the rich structure that we find in string theory,” she said — the innumerable ways that string theory’s multidimensional space-time can be folded in upon itself.

The piece ends with a different genre of hype:

Arkani-Hamed believes we are in the most exciting epoch of physics since quantum mechanics appeared in the 1920s.

I actually spent much of the day down in Princeton at the IAS, attending some of the talks at the Natifest in honor of Nati Seiberg’s 60th birthday. Lots of different ideas were discussed by the speakers, with essentially no mention of string theory. A serious journalist who talked to all the people Cole did would likely have noticed the obvious and framed the same material quite differently: string theory hasn’t worked out and theorists have moved on to other things, with the center of gravity of the subject now the deeper study of quantum field theory.

Update: I took a look again at the KC Cole review of my book, the second page of it is here. It was even more dishonest and unethical than I remember. She takes my

superstring theory has had absolutely zero connection with experiment,

and turns it into

Woit’s claim that string theory has “absolutely zero connection with experiment,”

Note how pulling a phrase out of sentence, you get to do fun stuff like change the tense of the sentence.

On the neutrino issue, Cole writes:

To say, as Woit does, that fundamental mysteries about neutrinos are being ignored will come as news to the dozens of physicists who’ve been working on these problems for years.

This is based on the fact that on page 93 of the US edition I write, after giving a description of the things the standard model leaves unexplained, including a parameter count that ignores neutrino masses:

One complication that has been ignored so far involves neutrinos.

and then go on to explain about the experimental evidence for neutrino masses. The “ignored so far” obviously means “ignored so far in this chapter”, not “fundamental mysteries about neutrinos are being ignored” by physicists.

When I contacted her to complain about this, her response was that there was nothing wrong with what she had done, and that, unlike me, she was an expert on neutrino physics.

The Quanta article has lots of her characteristic “quotes”, words or phrases pulled out of context. I’ll bet that lots of those misrepresent what the person being quoted actually said. I’d urge the Quanta editors to re-fact check this piece, asking for full quotes, in context.

Posted in This Week's Hype | 25 Comments

Fashion, Faith, and Fantasy

Posted on September 12, 2016 by woit

Roger Penrose’s Fashion, Faith and Fantasy in the New Physics of the Universe is finally being published this week. This is a bit of a landmark event, since the book has a long history, going back to a series of lectures that he delivered in 2003 at the university and IAS. At one point I remember watching videos of these lectures hosted by Princeton here, but these no longer seem to be available.

In giving these lectures, Penrose was walking into the lion’s den, bringing a forceful critique of string theory to the academic institution where it is most popular. Congratulations to Princeton University Press for publishing this despite it challenging the hegemonic viewpoint at Princeton (I had less luck with them: when my British publisher sent them my book for consideration way back when, they hired Lubos Motl to write an evaluation of it…).

Besides a mathematical appendix, the book is divided up into four parts:

  • Fashion: This is the section that deals with string theory, and Penrose’s central objection is to the use of extra spatial dimensions as a crucial part of the theory. When trying to use string theory as a unified theory, an assumption is made that one can take four space-time dimensions very large, and the rest very small, decoupling the large and small dimensions. Penrose argues that there is no reason to believe one can consistently do this, that there should be couplings between these degrees of freedom that cannot be ignored, leading to instability of the theory, rather than a stable ground state with large dimensions.

    The problem is that one doesn’t actually have a non-perturbative string theory in which one could properly study this issue. There’s no consistent theory, so Penrose can’t rigorously prove there’s a problem of this kind. He faces the generic problem of arguing not with a well-defined theory, but with people’s speculative hopes of what kind of theory might exist. I agree with him though that the extra dimensions are a deadly problem for the theory. Even if you accept the most optimistic hopes that Penrose’s and other problems will go away, you are still going to be left with the landscape problem. Everything known about conjecturally stable states with 4 large dimensions indicates an infinite complexity of such conjectural things, capable of giving you any physics you want, leaving the theory able to predict nothing and empty of explanatory power.

  • Faith: In this section Penrose addresses the measurement problem of quantum mechanics, pointing out correctly that our standard story about quantum mechanics introduces an “ontological shift”, indicating that something more is going on than a well-understood consistent framework. He favors the idea that perhaps the introduction of gravity into the usual framework could resolve this problem, backing this up with a dimensional analysis argument that a relevant effect could come from gravity, while being too small to be observable so far.

    Here I think he does an excellent job of explaining the usual story and why there’s a problem, but personally I’ve never been convinced that this problem requires new physical laws, non-linearities, or the introduction of gravitational effects. To me the “ontological shift” has always seemed due to the standard story being not a full theory of what happens in a real measurement process, but being a phenomenological approximation of what happens, with approximation needed to get a tractable description. As people build and study more complicated and larger fully quantum systems, the inadequacies of the standard story about “measurement” I think will become clearer, and we’ll get a better understanding of how classical behavior emerges from quantum laws, with no need to change those laws.

  • Fantasy: Here Penrose describes in detail some basic problems in the theory of cosmology, and how they are supposedly resolved by the theory of inflation. He explains that characterizing this as “fantasy” is not meant to be purely critical, that “fantasizing” about the moment of the big bang is what theorists do in the absence of compelling evidence, and that he just has other fantasies he thinks worthwhile.

    I don’t think I can do justice here to the depth and complexities of his arguments in this section. This is a topic involving subtle questions about the behavior of general relativity where Penrose is one of our deepest thinkers and greatest experts. While acknowledging some of the achievements of inflationary theory, part of his critique is related to that of Paul Steinhardt and others, showing that the theory doesn’t accomplish what it sets out to do, with the exponential expansion not providing a way to get observed homogeneity from arbitrary initial conditions. At the same time there is a lot more there, and this section seems to me that it should be required reading for anyone trying to make sense of fantasies of the description of the big bang itself.

  • A new physics for the universe?: In a final section, Penrose describes some of his more positive ideas addressing the problems pointed out in the earlier sections. This begins with a wonderful summary of the theory of twistors, and I strongly suspect that he’s right that this very different way of thinking about space-time geometry will ultimately be part of any successful integration of our understanding of quantization and geometry. That this geometry is very specific to four space-time dimensions provides yet another reason for skepticism about the fashion of theories with more spatial dimensions.

    I’m less convinced by his speculation about quantum state reduction, and by what he refers to as his “Conformal Crazy Cosmology”, although the emphasis on conformal invariance may very well be a correct one.

    In a final “Personal Coda” he explains that he sees himself not as a “maverick”, but as rather embodying an “inner conservatism”, somewhat allergic to the appeals of fashion. In particular:

    So when I heard that string theory – to which I had been distinctly attracted, partly because of its early use of Riemann surfaces – had moved itself in the direction of requiring all those extra spatial dimensions, I was horrified, and far from being tempted by the romantic attractions of a higher-dimensional universe. I found it impossible to believe that nature would have rejected all those beautiful connections with Lorentzian 4-space – and I still do.

A wonderful aspect of the book are Penrose’s many and detailed graphical illustrations, which have been made available separately by Princeton here. At their website you can also read the Preface, and an interview. Unfortunately I’ll be in Germany next week, missing Penrose’s book tour events here in New York, at the American Museum of Natural History and MoMath.

The range of non-crackpot speculative ideas about fundamental physics that normally get much attention is unfortunately quite narrow. In this environment Penrose is a breath of fresh air, providing here a different point of view on several topics, backed by serious and detailed argument. In some ways this is a popular book, but in others it is something else, deserving the attention of experts in the subject. I can’t recommend it too highly to anyone with a serious interest in fundamental questions about physics.

Update: A somewhat different version of this review is up at MAA Reviews.

Posted in Book Reviews | 34 Comments

Various and Sundry

Posted on September 8, 2016 by woit

A few unrelated items:

  • Maybe Multiverse Mania in the popular press is fading. The Atlantic has The Multiverse Idea is Rotting Culture, where the author points out

    In 2014, the New Scientist published an article called “Multiverse Me,” revealing that various lonely boffins take succor from the fact that alternate versions of themselves are leading fun lives full of emotional and sexual fulfillment, instead of solitudinous slogs through the stupid infinity of high-level algebra.

    They’re not jealous; they want the best for their alternate selves, they want them to be happy. How can you help? The answers given are all cop-outs; the scientists have decided to keep on living as if the multiverse didn’t exist (“The multiverse,” one says, “tells us that we should behave as if we were valuing the risks according to probabilities in a classical universe”), because if it does exist the implications are horrifying. Right now, infinite versions of yourself are dying in really horrible ways, not in spite of the fact that you’re lazily giving answers to a New Scientist reporter, but because of it. Every second you live, their suffering increases. If you stand on a cliff-edge and decide not to die, how many billions are smashed on the rocks? Jump now, and save them all.

  • Over at Scientific American, Lee Billings has a story about dark matter and the lack of evidence for WIMPS.
  • At CASW Showcase, an interesting interview with Natalie Wolchover.
  • Carlo Rovelli has posted on the arXiv The dangers of non-empirical confirmation, his contribution to the Why Trust a Theory? meeting discussed here and here.
  • Next week there will be a Natifest at the IAS, celebrating Nati Seiberg’s 60th birthday. I’ll try and get down there for the first day, leaving on a trip (more about that to come) later in the week.

    There’s a wonderful discussion with Seiberg arranged by Hirosi Ooguri that is well worth reading.

  • Denny Hill wrote recently to tell me about an interesting article on the history of the study of gravitational wave solutions, by him and Pawel Nurowski, now on the arXiv here.

Update: One more. Congratulations to Nigel Hitchin, whose 70th birthday celebrations are now ongoing. See here, here and here.

Posted in Uncategorized | 24 Comments

Weapons of Math Destruction

Posted on September 6, 2016 by woit

Cathy O’Neil’s important new book Weapons of Math Destruction, is out today, and if you’re at all interested in the social significance of how mathematics is now being used, you should go out and get a copy. She has been blogging for quite a while at Mathbabe, which you should be following, and is a good place to start if your attention span is too short for the book.

Cathy has had an interesting career path, including a period as my colleague here in the math department at Columbia. She left here to pursue excitement and fortune at a top hedge fund, D.E. Shaw, where she had a front-row seat at the 2008 financial industry collapse. A large factor in that collapse was the role played by mathematical models, and her book explains some of that story (for another take on this, there’s Models.Behaving.Badly from another Columbia colleague, Emanuel Derman). As far as I’ve ever been able to figure out, the role of mathematical modeling in the mortgage backed securities debacle was as a straightforward accessory to fraud. Dubious and fraudulent lending was packaged using mathematics into something that could be marketed as a relatively safe investment, with one main role of the model that of making it hard for others to figure out what was going on. This worked quite well for those selling these things, with the models successfully doing their job of obscuring the fraud and keeping most everyone out of jail.

While this part of the story is now an old and well-worn one, what’s new and important about Weapons of Math Destruction is its examination of the much wider role that mathematical modeling now plays in our society. Cathy went on from the job at D.E. Shaw to work first in risk management and later as a data scientist at an internet media start-up. There she saw some of the same processes at work:

In fact, I saw all kinds of parallels between finance and Big Data. Both industries gobble up the same pool of talent, much of it from elite universities like MIT, Princeton and Stanford. These new hires are ravenous for success and have been focused on external metrics – like SAT scores and college admissions – their entire lives. Whether in finance or tech, the message they’ve received is that they will be rich, they they will run the world…

In both of these industries, the real world, with all its messiness, sits apart. The inclination is to replace people with data trails turning them into more effective shoppers, voters, or workers to optimize some objective… More and more I worried about the separation between technical models and real people, and about the moral repercussions of that separation. If fact, I saw the same pattern emerging that I’d witnessed in finance: a false sense of security was leading to widespread use of imperfect models, self-serving definitions of success, and growing feedback loops. Those who objected were regarded as nostalgic Luddites.

I wondered what the analogue to the credit crisis might be in Big Data. Instead of a bust, I saw a growing dystopia, with inequality rising. The algorithms would make sure that those deemed losers would remain that way. A lucky minority would gain ever more control over the data economy, taking in outrageous fortunes and convincing themselves that they deserved it.

The book then goes on to examine various examples of how Big Data and complex algorithms are working out in practice. Some of these include:

  • The effect of the US News and World Report algorithm for college ranking, as colleges try and game the algorithm, while at the same time well-off families are at work gaming the complexities of elite college admissions systems.
  • The effects of targeted advertising, especially the way it allows predatory advertisers (some for profit educational institutions, payday lenders, etc.) to very efficiently go after those most vulnerable to the scam.
  • The effects of predictive policing, with equality before the law replaced by an algorithm that sends different degrees of law enforcement into different communities.
  • The effects of automated algorithms sorting and rejecting job applications, with indirect consequences of discrimination against classes of people.
  • The effects of poorly thought-out algorithms for evaluating teachers, sometimes driving excellent teachers from their jobs .
  • The effects of algorithms that score credit, determine access to mortgages and to insurance, often with the effect of making sure that those deemed losers stay that way.

Finally, there’s a chapter on Facebook and the way political interests are taking advantage of the detailed information it provides to target their messages, to the detriment of democracy.

To me, Facebook is perhaps the most worrisome of all the Big Data concerns of the book. It now exercises an incredible amount of influence over what information people see, with this influence sometimes being sold to the highest bidder. Together with Amazon, Google and Apple, our economy and society have become controlled by monopolies to an unparalleled degree, monopolies that monitor our every move. In the context of government surveillance, Edward Snowden remarked that we are now “tagged animals, the primary difference being that we paid for the tags and they’re in our pockets.” A very small number of huge extremely wealthy corporations have even greater access to those tags than the government does, recording every movement, communication with others, and even every train of thought as we interact with the web.

These organizations are just starting to explore how to optimize their use of our tags, and thus of us. Of the students starting classes here today in the math department, our training will allow many of them to go on to careers working for these companies. As they go off to work on the algorithms that will govern the lives of all of us, I hope they’ll start by reading this book and thinking about the issues it raises.

Posted in Book Reviews | 30 Comments

Templeton News

Posted on September 1, 2016 by woit

Looking at my list of items to blog about, I see most of them have some relation to the Templeton Foundation, so this will be a blog post just about those. To get some idea of the scale of Templeton’s activities, at the end of 2014 they had about \$3.2 billion in assets, and during 2014 had given away about \$185 million. For comparison, the NSF budget for FY2014 for physics was $267 million and for mathematics \$225 million.

One of the main goals of the foundation is to bring together science and religion. Among the many things they are funding to accomplish this is a \$871,000 grant to Arizona State University to fund Think Write Publish Fellowships in Science and Religion. If you’re a hard-up writer, these people will give you the opportunity to get $10,000 to write “creative nonfiction stories about harmonies between science and religion” and help you get them published.

Over the next few years, as you see things like this make it into the media, realize that this is not evidence of an intellectual trend, but a reflection of Templeton money and their agenda. ASU’s Lawrence Krauss is, for good reason, not happy.

To give an idea of the range of Templeton’s influence, just at ASU they’re funding several other large grants, including $745,000 for Representations of God (this and this), and $544,000 for emergent gravity. When you notice conferences, seminars, public lectures, etc. about “emergent gravity” in coming years, realize that some of them are happening because of Templeton’s agenda (one of the PIs is a Templeton Prize winner).

One of Templeton’s largest recent grants has been \$4.7 million to FQXI for research into “Physics of the Observer”. Among other things, this funded a recent conference at Banff.

A major interest of Templeton’s over the years has been “Genius”. Another of their large recent grants has been to the World Science Foundation for its Cultivating Genius Initiative.

Finally, there will be an interesting mathematics conference related to quantum field theory at Harvard October 8-10. I’ll likely be up in Boston visiting my brother and hope to maybe attend some of the talks. Funding for this is coming partially from the “Templeton Charity Foundation Switzerland”. I guess this is these people, some off-shoot of the Templeton Foundation, with exactly the same interests, They say they have made \$85.2 million in grants, a list is here.

Update: I was thinking of commenting that Templeton at least seemed to have slowed down its efforts to promote multiverse mania. But then I noticed this. If you want to know why Ira Flatow on NPR keeps bringing up the multiverse, \$150,000 in Templeton money might have something to do with it…

Update: I keep on finding out about more of these Templeton-funded things, they are endless. Templeton is funding an Institute for Cross-Disciplinary Engagement at Dartmouth. Themes to be investigated are “Can science alone explain the nature of reality?”, “Is there free will?” and “Is there purpose in the universe?”. Among their many activities will be an event featuring a dialogue between Sean Carroll and a Buddhist Scholar in San Francisco in February.

Posted in Uncategorized | 20 Comments

Not Ever Wrong

Posted on August 22, 2016 by woit

The “SUSY Bet” event in Copenhagen took place today, with video available for a while at this site. It appears to be gone for the moment, will put up a better link if it becomes available. An expensive bottle of cognac was presented by Nima Arkani-Hamed to Poul Damgaard, conceding loss of the bet. On the larger question of the significance of the negative LHC results, a recorded statement by Gerard ‘t Hooft (who had bet against SUSY), and a statement by Stephen Hawking (not in on the bet, but in the audience) claimed that if arguments for SUSY were correct, the LHC should have seen something, so they think nature has spoken and there’s something wrong with the idea.

The losers of the bet who spoke, (Arkani-Hamed, David Gross and David Shih) demonstrated the lesson about science that supersymmetry and superstring theory have taught us: particle theorists backing these ideas won’t give up on them, no matter what. They all took the position that they still weren’t giving up on SUSY, despite losing the bet. In more detail:

  • Arkani-Hamed was not a signatory of the original bet in 2000, but signed on to the later 2011 version. He explained today that at the time he thought chances of SUSY visible early on at the LHC were just 50/50 (with his 2004 work on split SUSY motivated by realizing that pre-LHC the conventional picture of SUSY at the electroweak scale was already ruled out). He attributed his decision to take the pro-SUSY side of a 50/50 bet to “optimism”, implying that this took place at a conference dinner where there may have been too much to drink. In his split-SUSY scenario, SUSY may yet show up at the LHC, or it could even be invisible there, requiring a higher energy accelerator. So, he’s not giving up on SUSY based on LHC results.
  • David Gross also is not giving up, arguing that fine tuning of a factor of 100 or 1000 is not a problem (invoking the large ratios that appear in the fundamental Yukawa couplings). He did say that young people might want to take this as reason to look for new ideas, but, for himself, felt “I’m too old for that”.
  • David Shih isn’t giving up either, arguing that there still was lots of data to come, plenty of room for SUSY to appear at the LHC, still believes we’ll discover SUSY, at the LHC or elsewhere.

One piece of misinformation promoted by several of the speakers was the idea that “everyone” back around 2000 believed in SUSY as the next new physics to be found. In my book (written in 2002-3) I wrote a long section about the evidence against SUSY, and, of course, if you look at the bet under discussion, in 2000 many more people (16 vs. 7) were taking the anti-SUSY vs. pro-SUSY side (at least in Copenhagen, but I think this reflects the general range of opinions).

No one today asked the obvious question “Is there any forseeable experimental data that would cause you to decide that SUSY was an idea that should be abandoned?”. I’m now not seeing any prospect in my lifetime of anything that would cause these or other SUSY proponents to give up (John Ellis has also announced that no matter what the LHC says, he’s not giving up). Unfortunately “Not Ever Wrong” is clearly the slogan of the (minority) segment of the particle theory community that long ago signed up for the vision of fundamental physics in which SUSY plays a critical part.

Update: There’s a blog entry from Natalie Wolchover about this. She has more detail about the final remarks from Gross that I mentioned:

“In the absence of any positive experimental evidence for supersymmetry,” Gross said, “it’s a good time to scare the hell out of the young people in the audience and tell them: ‘Don’t follow your elders. … Go out and look for something new and crazy and powerful and different. Different, especially.’ That’s definitely a good lesson. But I’m too old for that.”

Update: Video of the Copenhagen event is available here.

Update: I happened to be looking at Michael Dine’s 2007 Physics Today article on string theory and the LHC, noticed the side remark that “The Large Hadron Collider will either make a spectacular discovery or rule out supersymmetry entirely.” I wonder if he still thinks this, and whether we’ll ever see Physics Today publishing something updating its readers.

Update: Yet another news story about this, from Science News.

Posted in Uncategorized | 106 Comments

Various News

Posted on August 19, 2016 by woit

Before turning to other topics, congratulations to my Columbia colleague Wei Zhang, who was awarded the Gold Medal at the recent ICCM in Beijing.

On the HEP physics front, some news is:

  • On Monday at 1:30pm Danish time, at the conference on Current Themes in High Energy Physics and Cosmology that is part of the Simons Program at the Niels Bohr International Academy, there will be an event adjudicating the bet on SUSY first made in 2000 (described here, the wager is here).

    Nima Arkani-Hamed will act as referee, a bit unconventional since he’s on one side of the bet. On the other hand, it’s clearly the losing one and I have no doubt he’ll concede graciously. Others who may be heard from as part of the event include David Gross and Gerard ‘t Hooft.

    Video streaming should be available at this site, I guess the time is 7:30am New York time, maybe I’ll be up and watch during breakfast…

  • In related news, Frank Wilczek has conceded loss on a similar bet he made back in 2009 with Garrett Lisi, see here.
  • As for other similar bets I’m aware of, Lubos Motl is about to lose his bet with Adam Falkowski, and David Gross should be losing his with Ken Lane within the next year (perhaps he’ll comment on this on Monday). The interesting story to watch here will be whether this changes anyone’s behavior. Will Gross, Wilczek and others continue to point to SUSY extensions of the Standard Model as the promising future of the field, or will they acknowledge that this is an idea that hasn’t worked out?
  • In other HEP news, the “nightmare scenario” seems to have driven physicists at CERN to try human sacrifice to propitiate the angry Gods who are tormenting them in this manner.
  • There’s a conference going on in Banff organized by FQXI, and you can follow it to some extent on Twitter. I’m somewhat of a skeptic about claims to have deep new insights into physics based on what seem like simple, vague natural language arguments. Not clear if the 140 character limit of Twitter is a good or bad thing in trying to capture such arguments.
  • Another of the vague sort of claims I’m dubious about is the “ER=EPR” one described here. On the other hand, this at least appears to have important applications.
  • Also on the dubious HEP news front, there have been lots of news articles recently about a supposed new “Fifth Force”, generated by a press release from UC Irvine promoting a PRL paper by UCI theorists. This story had been debunked a couple months ago by Natalie Wolchover at Quanta (see here).

    The usual hit on science journalism is that the work of scientists is hyped and misrepresented by journalists, but I think this shows an all too common example of the real problem: hype from physicists and their institutions (egged on by PRL), with journalists trying to hold the line against it (and not always succeeding).

  • Finally, there’s a wonderful interview with Edward Witten (part of a TV program in Dutch) that I would guess was filmed in 1999-2000 [maybe 1997?] and is available here. Witten is there quite optimistic about the prospects of string theory, and of course I’m curious whether and how the intervening years have changed his point of view. On other topics the interview is quite fascinating, doing an unusually good job of getting the normally reticent Witten to talk a bit about life and wider issues (as well as demonstrating an admirable refusal to get provoked into pontificating about various questions he’s not expert in).

Update: For a detailed explanation from one of the theorists working on the supposed “fifth force”, see here.

Posted in Uncategorized | 27 Comments

The Nightmare Scenario

Posted on August 10, 2016 by woit

Now back from a short vacation, and there seems to have been a lot happening on the debate over fundamental physics front. From the experimentalists, news that the Standard Model continues to resist falsification:

  • At ICHEP, as expected, new data from ATLAS and CMS ruled out the supposed 750 GeV state that would have indicated new physics.
  • Also at ICHEP, significantly stronger bounds on SUSY: gluinos ruled out up to 1.9 TeV, stops up to 900 GeV.

Recall also the recent results from LUX and PandaX (discussed here) putting stronger bounds on the sort of WIMP dark matter supposedly a feature of SUSY models.

In addition, there was news from IceCube ruling out the possibility of certain models of light sterile neutrinos (paper here, a Nature news story here).

For what it all means, you should of course consult Resonaances (and read a profile of Jester, The Rogue Blogger Who Keeps Spoiling Physics’ Biggest News) as well as Tommaso Dorigo (and some coverage from Physics World featuring him).

From an even wider perspective, see Sabine Hossenfelder for The LHC “nightmare scenario” has come true and Natalie Wolchover’s piece on the “nightmare scenario”, What No New Particles Means for Physics (by the way, congratulations to Wolchover on some well-deserved awards, including this one). My own views on this are well known: this was in some sense a major theme of my book, and among other places I’ve written about this, see for example a 2013 Edge essay.

My perspective on this is in some ways similar to Hossenfelder’s, but I draw very different conclusions, strongly disagreeing with her criticism of “reliance on gauge symmetry”, and “trust in beauty and simplicity”. This hasn’t been what theorists have been doing for 30 years. The string theory unification ideology has led to an emphasis on extremely complex and ugly models, with gauge symmetry not a fundamental feature at all. Yes, she’s right to point to “A failure of particle physicists to uncover a more powerful mathematical framework to improve upon the theories we already have”, but I’d argue that that failure is due to an insistence on looking in the wrong place.

Wolchover’s piece captures some of the current angst well, for instance quoting Maria Spiropolu about SUSY as follows:

“We had figured it all out,” said Maria Spiropulu, a particle physicist at the California Institute of Technology and a member of CMS. “If you ask people of my generation, we were almost taught that supersymmetry is there even if we haven’t discovered it. We believed it.”

Arkani-Hamed is as quotable as ever, saying the lesson of all this failure is

“There are many theorists, myself included, who feel that we’re in a totally unique time, where the questions on the table are the really huge, structural ones, not the details of the next particle. We’re very lucky to get to live in a period like this — even if there may not be major, verified progress in our lifetimes.”

I suspect that there are quite a few physicists, of my generation and later, who don’t necessarily feel “very lucky” to get to live in a period of no significant progress in the past 40 years, with the prospect of none in our lifetimes. It would be great if the “huge, structural” questions really were on the table, but I’ve seen little interest among theorists in such questions, beyond whatever the fad of the day related to AdS/CFT might be.

Also finishing up while I was away was the Strings 2016 conference, and for the state of the subject you might want to watch David Gross’s “Vision” talk (video here, I had to download the whole thing to watch it, streaming was unusable). I think Gross was right in pointing to work on the so-called “Sachdev-Ye-Kitaev” model as perhaps the most interesting thing being discussed at the conference. This is an exactly solvable large-N quantum mechanical model exhibiting features of holography. A good place to start learning about it is Kitaev’s KITP lectures here and here.

Gross also went over some history, noting that some current topics in string theory echo back to 1967 work of Mandelstam (and that Gross himself had written a paper at that time on this material, so next year will be a 50th anniversary of his engagement with the subject). As for the current state of the theory, his take is much the same as that he has talked about at many earlier Strings conferences: string theory is now a “framework” encompassing QFT and most of the rest of fundamental physics, but we don’t really know “what string theory is”. To me it’s very unclear why one is supposed to believe so strongly in the overarching role of a set of ideas that aren’t well-defined and have been an utter failure at explaining anything about particle physics. Soon he’ll have to pay off his SUSY bets, but this doesn’t seem to have changed his conviction that superstring theory unification is on the right track. He ended with his usual sign-off “The best is yet to come”, but this time added a parenthetical “I hope it comes quick”.

Another new Wolchover piece well worth reading is about Miranda Cheng and her work on modular forms and string theory on K3 surfaces. I think this sort of work on the boundary of mathematics and physics makes clear the problem with string theory and mathematics: things are complicated and ugly if you try and make the theory look like the real world. You get beautiful ideas and great mathematics when you ignore the supposed connection to the real world and go in another direction. The problem is that often, instead of pursuing good mathematical ideas where they lead, people doing this feel the need to stick to some connection to the failed idea. Here’s what Cheng has to say:

I personally always have the real world at the back of my mind — but really, really, really back. I use it as sort of an inspiration for determining roughly the big directions I’m going in. But my day-to-day research is not aimed at solving the real world. I see it as differences in taste and style and personal capabilities. New ideas are needed in fundamental high-energy physics, and it’s hard to say where those new ideas will come from. Understanding the basic, fundamental structures of string theory is needed and helpful. You’ve got to start somewhere where you can compute things, and that leads, often, to very mathematical corners. The payoff to understanding the real world might be really long term, but that’s necessary at this stage.

For another physicist still enthusiastic about string theory, see this interview with Brian Greene, somehow motivated by a sci-fi horror series, Netflix’s “Stranger Things”.

Posted in Uncategorized | 42 Comments