This Week’s Hype, Part III

Posted on August 25, 2011 by woit

Today’s Wisconsin State Journal covers the String Phenomenology 2011 conference going on in Madison this week, where, according to the organizers, about 100 scientists are discussing how to “test string theory”:

The Madison conference is something of a milestone in the study of string theory, Shiu said, because it represents 10 years of thought and advances. “It means the field is moving forward, that interesting things are going on,” he said.

Kane agreed and said much of the conference focuses on the predictive powers of string theory. If the theory can predict the existence of certain particles or behaviors, Kane said, and those are then borne out by successful experiments at projects such as the Large Hadron Collider in Europe, string theory would become an accepted explanation for the workings of the universe.

Kane has a long history of making “predictions” based on string theory, including a 1997 Physics Today article String Theory is Testable, Even Supertestable, which gave a plot showing the masses of all superpartners, in the range of 50-300 GeV. His latest “generic predictions” from the conference are here(see page 22). These days most of the superpartners have for some reason moved up to 50 TeV, well beyond any hope of observation at the LHC. There’s a gluino though at a bit above current bounds of around 500 GeV, and claims that, with the right sort of analysis, this will be visible. Once this analysis gets done, one suspects the gluino will go join its friends at much higher masses. There’s also a “prediction” of the range of the Higgs mass, which happens to be within the range not yet ruled out.

Another conference going on at the moment is at Les Houches. There Luis Alvarez-Gaumé gave a survey talk about string theory, and in his conclusion he makes quite clear what he thinks of efforts like Kane’s:

One cannot make LHC-accessible predictions.

Update: After posting this, I remembered that I’d once read a much more interesting story about theoretical physics in the Wisconsin State Journal. This was from when Dirac, not string phenomenologists, came to town, and gave the paper an interview.

Posted in This Week's Hype | 12 Comments

This Week’s Hype, Part II

Posted on August 21, 2011 by woit

String theory hype is still coming fast and furious, so much so that the latest edition of This Week’s Hype needs to be a double issue. Today we learn that Black holes and pulsars could reveal extra dimensions, solving that thorny problem of testing string theory:

String theory, which attempts to unify all the known forces, calls for extra spatial dimensions beyond the three we experience. Testing the theory has proved difficult, however.

Now John Simonetti of Virginia Tech in Blacksburg and colleagues say black holes orbited by neutron stars called pulsars could do just that – if cosmic surveys can locate such pairings. “The universe contains ‘experimental’ setups we cannot produce on Earth,” he says.

The source of the hype isn’t really new though, they were featured a few years ago in an earlier edition of This Week’s Hype.

Posted in This Week's Hype | 7 Comments

Sunday Night Higgs?

Posted on August 18, 2011 by woit

Lepton-Photon 2011 begins Monday morning, the schedule is here. It should start off with a bang, with the latest Higgs search results from ATLAS and CMS presented starting at 11:20am local time, the middle of Sunday night here. There will be a press conference on Wednesday.

If the hints of a Higgs signal seen in the data presented last month at EPS-HEP 2011 are real, they should be more pronounced in the new data (the experiments have now collected about twice as much data as that used in the analyses presented at EPS-HEP 2011). The Higgs Combination Group should by now have produced a combined analysis using last month’s data from the ATLAS + CMS and presumably that will also be released on Monday or soon thereafter. They have just today released a new document giving the details of how the combination is done: Procedure for the LHC Higgs boson search combination in summer 2011. Still holding out on us though in terms of the real data, that document just shows toy data…

Update: The latest rumor I’m hearing is that the only analyses updated with new data (nearly twice as much) since EPS-HEP that will be available Monday will be from individual channels. Analyses combining the different channels won’t be ready for another 2 to 3 weeks. I still think though that we should see the CMS+ATLAS combination of the old data shown at EPS-HEP. So, if the Higgs is there, a definitive signal may still not quite yet be available. These people do need to take a vacation sometime in the summer…

Update: The news is that CMS and ATLAS have produced new combinations (although the combination of older ATLAS + CMS data has not been released, and I’d love to know why…). The bottom line is that the hints of a Higgs around 140 GeV have weakened with the addition of more data. A simplified summary of the current situation would be:

  • No Higgs above 145 GeV
  • In the region 135-145 GeV, both experiments are seeing somewhat more events than expected from background, but less than expected if there really was a Higgs there.
  • Not enough data to say anything about 115-135 GeV, the Higgs could still be hiding there. If so, a malicious deity has carefully chosen the Higgs mass to make it as hard as possible for physicists to study it.

    • More details available on the conference slides that should be available here. Tommaso Dorigo and Matt Strassler have commentary.

    Update: Still no word on why no CMS+ATLAS combination has appeared. Philip Gibbs has hacked together an unofficial version (see here and here). Comparing the EPS data to the latest, one sees clearly that a marginally significant signal consistent with a Higgs has weakened quite a bit with the new data (and thus, there was little to no evidence for such a Higgs in the new data). Also worth reading, commentary from Jester here.

    Posted in Experimental HEP News | 45 Comments

    String Theorists Suggest Space Wormholes Possible

    Posted on August 18, 2011 by woit

    I was just out for a bike ride, during which an idle thought came to me about a rule of thumb that might deserve publicity. This rule of thumb is that the mention of wormholes in a popular science book, TV program, etc., indicates that real science is not what’s being discussed. When I got back to my office, I found that USA Today has a new story: String theorists suggest space wormholes possible. The source of the story is this preprint.

    Via Twitter, the story’s author did get the obvious response to this claim: this isn’t news since everything is possible in string theory.

    Posted in This Week's Hype | 13 Comments

    $100 Million From Simons and Simonyi for the IAS

    Posted on August 18, 2011 by woit

    The Institute for Advanced Study in Princeton announced today that Jim Simons and Charles Simonyi will donate \$100 million to the Institute, in the form of matching funds for a \$200 million campaign mainly aimed at increasing the endowment. For some idea of previous fund-raising by the IAS, see here.

    Simons and Simonyi have donated significant sums to the IAS in the past, including \$6 million from Simonyi to endow a professorship for Witten. The IAS has about 25 permanent professors, with salaries reaching above \$300K/year. To get some idea of the scale of the new endowment funds, if they all went to new permanent professorships (unlikely), the number could be doubled or more. This kind of sizable increase of resources for prestigious pure research positions in math and physics, funded by huge fortunes made in the technology and financial industries, is part of a trend, with Perimeter and the Simons Center at Stony Brook two other noteworthy examples.

    Posted in Uncategorized | 9 Comments

    Does String Theory Predict Low Energy Supersymmetry?

    Posted on August 16, 2011 by woit

    It used to be that string theorists would respond to arguments that string theory predicted nothing with the claim that it predicted supersymmetry. For example, in an interview with Witten done for the PBS Elegant Universe series, one sees:

    NOVA: It seems like the standard criticism of string theory is that it isn’t testable. How do you respond to that criticism?

    Witten: One very important aspect of string theory is definitely testable. That was the prediction of supersymmetry, which emerged from string theory in the early ’70s. Experimentalists are still trying to test it. It hasn’t been proved that supersymmetry is right. But there is a very precise relationship among the interaction rates of different kinds of particles which follows from supersymmetry and which has been tested successfully. Because of that and a variety of other clues, many physicists do suspect that our present decade is the decade when supersymmetry will be discovered. Supersymmetry is a very big prediction; it would be interesting to delve into history and try to see any theory that ever made as big a prediction as that.

    Of course the problem with this was always that supersymmetry had to be broken somehow, and string theory said nothing about how to break it, not even the scale of the breaking. Back in 2004 when the anthropic landscape business began, Susskind was enthusiastic about the idea that it could be used to predict the scale of supersymmetry breaking, and Michael Douglas started working on computations counting string vacua that were supposed to say something about this (I’ve followed this story in several blog postings, an early one was here). The bottom line quickly became clear: a host of problems make this impossible, string theory remains incapable of predicting anything about this.

    Today at the Simons Center, Douglas gave a talk entitled Does String Theory Predict Low Energy Supersymmetry? (video available here), and not surprisingly the conclusion is still that string theory predicts nothing about this. Amusingly, someone in the audience took exception to Douglas saying that string theory doesn’t now make predictions, and one gets to hear Douglas try and explain to his fellow string theorist what a real prediction is. The video quality is great, but the sound doesn’t work so well when two people are loudly trying to talk over each other.

    This particular talk was held indoors, for a report on what the outdoor ones have been like, see here.

    Posted in Uncategorized | 13 Comments

    The Fabric of the Cosmos on PBS

    Posted on August 15, 2011 by woit

    A four-part NOVA series based upon Brian Greene’s The Fabric of the Cosmos is coming to PBS this fall, starting November 2. In some sense this is a follow-on to his wildly successful The Elegant Universe NOVA series from 2003, which was largely devoted to promoting string theory. From the program description and preview it appears that the new shows don’t emphasize string theory, although the fourth of the series promotes the Multiverse (Clifford Johnson joins the effort here), along the lines of Brian’s latest book The Hidden Reality.

    Posted in Uncategorized | 32 Comments

    Talks at the KITP

    Posted on August 12, 2011 by woit

    Back now from vacation, and found that there have been quite a few interesting talks at the KITP in Santa Barbara this week which are now available on-line:

  • Since the EPS-HEP conference last month, the “First Year of the LHC” program has some interesting results to discuss. Yesterday Matt Reece gave a talk on Assessing SUSY after 1 fb -1, on the hot topic of how worried SUSY proponents should be that no sign of SUSY has been found at the LHC so far. He takes the point of view that the failure of direct collider searches to see anything is much less of a problem than the pre-LHC failure of SUSY to show up indirectly in flavor physics or in cosmology. While it’s true that SUSY was in trouble pre-LHC, there’s psychologically a big difference between indirect effects not showing up, and directly looking for something and finding it’s just not there. The discussion with the audience is quite interesting, with some audience members a lot more worried about SUSY. One of them reminded people that SUSY is supposed to solve naturality problems, so relatively light squarks were expected, but now “those models are being screwed.” Someone else (Lisa Randall, I think) reacted to Reece’s mentioning R-parity violating models as one way to evade the LHC limits with “Is there any good reason to think about R-parity violation?” All in all, the discussion gives a good indication of what prominent theorists are thinking now that the initial results from the LHC are in.

    About a year ago on this blog, I had the following exchange with a well-informed phenomenologist on this blog:

    If there’s no sign of supersymmetry in this year’s LHC data, how discouraging will this be for those who expect to see supersymmetry at this energy scale?

    In 2010 data? Not discouraging at all. In 2011 data? Fairly discouraging. In 2014 data? Enormously depressing.

    The LHC has now gathered as much data as expected for all of 2011, so I think that with the negative results, “fairly discouraged” is where SUSY proponents would have expected to be and are now. “Enormously depressed” is on the agenda for late 2014, early 2015, after the LHC reaches design energy.

  • Adam Falkowski, the Jester of Resonaances fame, also gave an interesting talk this week, on Higgsless theories.
  • On the mathematical end of things, Ed Frenkel gave a very nice expository “Blackboard Lunch” talk on What do Fermat’s Last Theorem and Electro-magnetic Duality Have in Common?, explaining to physicists a bit about the Langlands program and the connection between geometric Langlands and QFT pioneered by Witten and developed by him and others over the past few years. For something more technical with newer ideas about the relationships between TQFT, gauge theory and representation, see David Ben-Zvi’s talk on Geometric Character Theory.
    • Posted in Langlands, Uncategorized | 13 Comments

    This Week’s Hype

    Posted on August 5, 2011 by woit

    I noticed today that BBC News has a story headlined ‘Multiverse’ theory suggested by microwave background that assures us that:

    The idea that other universes – as well as our own – lie within “bubbles” of space and time has received a boost.

    After taking a look at the PRL and PRD papers that are behind this, it’s clear that a more accurate title for the story would have been “‘Multiverse’ theory suggested by microwave background – NOT”. As usual, the source of the problem here is a misleading university press release, one from University College London entitled First observational test of the ‘multiverse’. Somehow the press release neglected to mention something one might think was an important detail, the fact that this “First observational test” had a null result.

    It’s well-known that one can find Stephen Hawking’s initials, and just about any other pattern one can think of somewhere in the CMB data. The authors of the PRL and PRD papers first put out preprints last December (see here and here). In these preprints they essentially claimed to have found four specific features in the CMB where the hypothesis that they were due to bubble collisions was statistically preferred. A guest post by Matthew Johnson at Cosmic Variance explained more about the preprints. I didn’t understand their statistical measure, so asked about it in the comment section, where Matthew explained that, by more conventional measure, the statistical significance was “near 3 sigma“.

    It turns out that the PRL and PRD papers differ significantly from the preprint versions. In the acknowledgements section of the PRD paper we read that:

    A preprint version of this paper presented only evidence ratios confined to patches. We thank an anonymous referee who encouraged us to develop this algorithm into a full-sky formalism.

    and the result of the new analysis asked for by the referee is summarized in the conclusion of the paper:

    The posterior evaluated using the WMAP 7-year data is maximized at Ns = 0 [Ns is the average number of observable bubble collisions over the full sky], and constrains Ns < 1.6 at 68% confidence. We therefore conclude that this data set does not favor the bubble collision hypothesis for any value of Ns. In light of this null detection, comparing with the simulated bubble collisions... [various bounds ensue]

    So, the bottom line is that they see nothing, but a press release has been issued about how wonderful it is that they have looked for evidence of a Multiverse, without mentioning that they found nothing. As one would expect, this kind of behavior leads to BBC stories about how the Multiverse has “received a boost”, exactly the opposite of what the scientific evidence shows.

    Update: The FQXI web-site has an article about this. In it, the authors seem far more interested in promoting their PRL paper as “first test of the multiverse” than in acknowledging that a referee made them do a better test of the idea and they got a null result. There’s no mention of the null result in the article.

    Update: News stories based on this keep on coming. The latest: Proof of a multiverse discovered?

    Posted in Multiverse Mania, This Week's Hype | 25 Comments

    News From Simons Center

    Posted on July 28, 2011 by woit

    The Simons Center for Geometry and Physics at Stony Brook has a new web-site, and this week their annual summer workshop got underway, talks available in very high quality video here. Luca Mazzucato, a postdoc there, has started putting together an Outreach section of the web-site, which now includes some wonderful interviews with various theorists, often covering topics well-known on this blog. The last of the interviews looks the most intriguing, it promises “the formula of love”. Unfortunately, when you try and get access to this intriguing formula, for now you find that it is password-protected…

    I’ll be spending much of the next two weeks on vacation in Scotland. Blogging may be light to non-existent.

    Posted in Uncategorized | 5 Comments