Last Links For a While

In a few days I’m heading to East Africa for a couple-week long trip, planning to be in Uganda on November 3 for the (short) total solar eclipse that day. This will be followed by a few days in London, then back here with regular programming resuming around November 11. While away I’ll shut off the commenting system, since I’m hoping to not have internet access during most of the trip.

Here’s some short items that might be of interest:

  • For the latest from CERN about SUSY, see this overview from ATLAS. The bottom line is quite simple: zilch, in every channel examined. Limits on a gluino mass are about 1.2 TeV, and there seems little prospect of much change until 2015, when results at 13 TeV start to come in. A naive extrapolation says that ultimately the LHC should be able to set limits on gluino masses of up to 2 TeV. Pre-LHC, the limits were about 300 GeV (from the Tevatron). I don’t know anyone who is optimistic that it will turn out that the 62.5% energy jump in 2015 will find something when the 400% energy jump didn’t (and the theoretical arguments for SUSY implied that it should have already been seen at the Tevatron).
  • Steven Weinberg has an article about the current state of cosmology and particle physics, entitled Physics: What We Do and Don’t Know. About string theory he has this to say:

    String theory is attractive because it incorporates gravitation, it contains no infinities, and its structure is tightly constrained by conditions of mathematical consistency, so apparently there is just one string theory. Unfortunately, although we do not yet know the exact underlying equations of string theory, there are reasons to believe that whatever these equations are, they have a vast number of solutions. I have been a fan of string theory, but it is disappointing that no one so far has succeeded in finding a solution that corresponds to the world we observe.

    The main reason for disappointment about string theory is not that a solution corresponding to the SM hasn’t been found, but that the theory predicts nothing at all. All indications are that the dead end that string theory has hit is not that (if one could actually figure out what the theory is…) of no SM solution, but that of so many solutions that you can get anything you want. Unfortunately Weinberg seems to be of the “if a fundamental theory predicts nothing, that’s too bad, but maybe how the world works” camp, rather than the more standard “if a fundamental theory predicts nothing, it’s a bad fundamental theory” camp. He goes on to argue that we may have to just give up on fundamental physics and be content with this theory that predicts nothing:

    Such crude anthropic explanations are not what we have hoped for in physics, but they may have to content us. Physical science has historically progressed not only by finding precise explanations of natural phenomena, but also by discovering what sorts of things can be precisely explained. These may be fewer than we had thought.

    Back in 1977, in the wake of the great advances of the Standard Model, Weinberg famously made the statement that:

    The more the universe seems comprehensible, the more it also seems pointless.

    Presumably the universe is still pointless, but now the argument seems to be that it’s also incomprehensible.

  • Unlike Weinberg, Frank Wilczek hasn’t been a fan of string theory. From a recent interview:

    3. Is String Theory a dead end? Is there news coming, regarding scientific advances, or experimental confirmations?

    Many very smart people continue to work on string theory, and I expect that they’ll continue to do interesting work, in mathematics if nothing else. Whether they’d be more productive doing something else, is another question. It is unfortunate that in the early days people got carried away, and promised much more than the theory
    could reasonably be expected to deliver.

    and about anthropics:

    It is the scope of anthropic reasoning that’s debatable. I hope we can avoid appealing to it very much in fundamental physics, but time will tell.

  • According to the Stony Brook newspaper though, based on information from Michael Douglas, all is well with string theory:

    String theory has done quite well so far in explaining all of the forces of the universe. The theory has matured, and so have the mathematical equations it has produced. An equation describing the universe is considered successful if it is symmetrical. What that means is if the equation is taken apart and its components rearranged, it should still produce the same conclusion. If the rearrangement of an equation does not yield the same result, it is deemed unstable and not a good descriptor of the universe or its forces.

    The equations that have stood up to the test of symmetry have predicted the existence of particles that help bridge the gap between general relativity and quantum field theory. For example, string theory predicts a particle called the graviton, thought to be a closed loop string that is responsible for the gravitational force…

    Gravity is weak.

    String theory not only predicts the particle that constitutes gravity, it also helps describe why it is so weak…

    Currently, the ability to test the predictions from string theory is very limited and some have said that this roadblock is impossible to overcome.

    Douglas thinks otherwise.

    The next phase of this theory will likely take a lot of hard work and fresh ideas. String theory has made enormous strides in the relatively short amount of time that it has been around, and it is thought by many to be the most promising of the so-called “theories of everything.”

    In a few more years, who knows what exciting advances could be in store?

    The article doesn’t mention Douglas’s decision to stop working on string theory and go to work for a hedge fund.

  • The Financial Times has its own take on the current state of fundamental physics research, with an article on The new physics.
  • Also at the Financial Times is a good survey of Physicists and the financial markets, describing various current activities of physicists now working in the financial industry.
  • Harvard University Press has just released a new book by Steve Nadis and S.-T. Yau, a history of the Harvard math department entitled A History in Sum: 150 Years of Mathematics at Harvard. It concentrates on the period 1825-1975, and I enjoyed it quite a bit. It ends right about the time I arrived there as a student, so covered history that I never had known much about.

    Harvard’s role as a mathematics research institution began with Benjamin Peirce, who taught there from 1831-1880. It only started to become a world-class institution around 1900, with young faculty who had gone to Germany for their training. The book covers a fairly long list of great 20th-century Harvard mathematicians (including George David Birkhoff, Morse, Whitney, MacLane, Ahlfors, Gleason, Mackey, Zariski, Brauer and Bott), and makes a serious attempt to explain some of the mathematical ideas they developed. As a result, a large part of the book is not just history, but actual exposition at a popular level of a wide range of mathematics, together with quotes from many other prominent mathematicians about the significance of the ideas.

    If you’re interested at all in the history of mathematics, this book is well-worth finding a copy of.

  • David Appell has an article about the SSC, the major disaster for US HEP research. Next year should see a book on the topic by Michael Riordan, Tunnel Visions: The Rise and Fall of the Superconducting Super Collider.
  • The Simons Foundation Quanta magazine continues to put out many high quality stories about science, with one of the latest an article by Natalie Wolchover about experiments searching for neutrinoless double beta decay, which would indicate a Majorana neutrino mass term.
  • The SETI institute has a series of SETI Talks, available on YouTube, with the latest featuring Joe Polchinski on Black Holes and Firewalls.
  • The Boston area Joint Math Colloquium this week with have Edward Frenkel speaking on The Langlands Program and Quantum Physics. Afterwards you can go up to Harvard Square and get him to sign a copy of his new book.
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32 Responses to Last Links For a While

  1. Visitor says:

    “The main reason for disappointment about string theory is not that a solution corresponding to the SM hasn’t been found, but that the theory predicts nothing at all. ”

    His disappointment, or yours?

  2. Peter Woit says:

    Visitor,
    I don’t think it’s just my opinion that string is disappointing because it can’t predict anything. Surely Weinberg would also agree this is a cause for disappointment. I’d be curious what he thinks though of the possibility of a string theory landscape that has a SM solution, but so many others that one can’t extract a prediction about anything out of it. Would the existence of this SM solution remove the disappointment, and he would then be happy with a non-predictive theory? I kind of doubt it.

    This is the problem with the point of view he’s selling at the end. If you have a testable theory that predicts that certain parameters (e.g. the CC) are enviromental, that’s one thing. But an untestable theory that predicts nothing is a different story, and can’t be saved by trying to argue that all the things one might hope to use as tests are just environmental. Right now string theory is in the second category, with no prospects for entering the first.

  3. johnnythelowery says:

    Going to Africa?: There is a great series on Netflix which aired in the UK on TV called ‘Long Way Down’ where two guys (one, an actor you might know—Star War’s Ob1kenobe) ride motorcyles from top of Scotland to Cape Town. It presents a videoblog view of the various countries of Africa and the topology of the various countries. The series is different than anything before about Africa. Eye opening.

  4. johnnythelowery says:

    You say String theory predicts nothing at all, which is a fascinating observance. but see here in the same posting; Douglas claim’s that it predicts the Graviton? So, there seems a conflict with your preposition.

  5. Peter Woit says:

    johnnythelowery,

    I’ll just quote Lisa Randall about that prediction: “yes, string theory predicts gravity, ten-dimensional gravity…”

  6. Yatima says:

    I feared that “Physicists and the Financial Market” would be enragingly content-free with “physics!!” mysticism, Physics Envy and the obligatory mention of “black swans” but it’s actually a nice introduction.

    Oxford university’s J Doyne Farmer builds “Crisis”: The project is an attempt to do in economics what is common in physics, to build an agent-based model not from a mathematical formula or theory but from the ground up, by simulating the interactions of all the component parts. “The failure to embrace things like simulation has inhibited progress in economics,” Farmer says. “Physics, meteorology, chemistry, biology, even other branches of social science have got major impetus because of serious use of computers as a simulation tool.”

    It’s about time, but it has as much to do with physics as does simulation of large-scale neural networks: which is to say nothing at all, except that papers may exhibit differential equations. However, I fear that the model will be “value-neutral” and not factor in things that traditionally make the worst rise to the top. A EU-financed project that models “political entrepreneurs” who wreak havoc while selling crony-capitalist enrichment schemes in the nice flashy box of “Keynesianism”? A likely outcome.

  7. morris says:

    Peter Woit,

    As an aspiring physicist, born and currently living in Nairobi, Kenya am excited to hear of your planned trip to East Africa. If you do happen to pass through Nairobi, a group of us, currently studying at Nairobi University would be happy to meet and show you around. We would be honoured to meet a practising physicist at the frontier of knowledge. Your blog has been an inspiration to most of us young aspiring theoretical physicists. Karibu East Africa.

  8. Bee says:

    It’s not that string theory doesn’t predict anything. At the very least it predicts string excitations. It’s just that the things that it does reliably predict aren’t presently possibly to test experimentally. Alas, the same could be said about pretty much all other approaches to quantum gravity. The reason people are ‘disappointed’ is not that it’s a bad theory, but that it’s been oversold. The pendulum will swing again once people notice that LQG also doesn’t ‘predict anything’… And then they’ll all end up doing qg phenomenology :p

    Have a safe trip :)

  9. vmarko says:

    Bee,

    “The pendulum will swing again once people notice that LQG also doesn’t ‘predict anything’…”

    My guess is that the majority of us already know this. The difference is that nobody is trying to advertise LQG as a “theory of everything”, “the only game in town”, “*the* solution of the QG problem” etc. :-)

    Best, :-)
    Marko

  10. vmarko says:

    Peter,

    “The main reason for disappointment about string theory is not that a solution corresponding to the SM hasn’t been found, but that the theory predicts nothing at all.”

    I have noticed lately that people working in string theory have changed their opinion on what ST actually is — it is a *formalism*, rather than any particular theory. In a sense, they now consider ST on par with QFT, which is also just a formalism, and has no serious predictions to give by itself. The word “theory” in the name of both is a misnomer.

    Only when one specifies a particular landscape solution in ST, or a particular gauge group and a set of fields in QFT, does one get a theory (or more precisely, a model) that has some concrete predictions.

    This change in the point of view by string theorists apparently does away with the “no predictions” criticism — namely, now ST is not even *supposed* to give any predictions, until one provides additional input which picks a particular model within ST. As far as I can see, this new point of view actually makes some sense out of ST. What’s your opinion on this?

    Best, :-)
    Marko

  11. Avattoir says:

    Is there an equation that predicts the chances of a blog becoming invaded by Von Misians?

  12. Jason Starr says:

    You misspelled “Peirce”.

  13. Peter Woit says:

    morris,

    Thanks so much for the offer! I wish I could take you up on it, but unfortunately the only time I’ll be able to spend in Kenya this trip will be changing planes in Nairobi airport.

  14. Peter Woit says:

    Thanks Jason, fixed.

  15. wolfgang says:

    >> when results at 13 GeV start to come in
    I assume you mean 13TeV ?

  16. Per Östborn says:

    You often hear that QFT and string theory are analogous frameworks or formalisms, that none of them are predictive theories per se. I’m an outsider to the field, and Peter may be tired of the entire discussion, but I try to orientate, and I wonder if the following fundamental distinction is proper:

    in the QFT approach you build a theory step by step by adding fields, altering the gauge group, and so on. At each step in the construction you may have a unique theory that makes unique predictions what to see and not to see in the next experiment. If this experiment does not agree with the theory, you just add another building block, or adjust parameters.

    In contrast, in string theory you begin with a unique theory (ideally), having a vast, possibly infinite number of solutions. Each new experiment makes it possible (in principle) to exclude large chunks of solution space, but regardless how many experiments you make, there may still be so many solutions left that conform with all experiments so far that the outcome of the next experiment is not restricted at all. In this sense string theory may therefore forever lack predictive power. You may have to make an infinite number of experiments to nail the correct solution.

  17. fuzzy says:

    among the various opinions on string theory, i think that it should be fair to remind those of glashow’s and feynman. maybe, one could admit that these chaps have been much more long-sighted of those who needed the lhc, before they can begin to think …

    (enjoy your travel, peter!)

  18. Kent says:

    Thanks for the links, Peter.
    There is enough reading material linked to here that it will keep me busy for the two weeks you are offline.

  19. Peter Woit says:

    wolfgang,
    Thanks! Fixed.

    vmarko,
    This is an FAQ, I really need to get back to updating the FAQ I started for the blog, maybe later today..

    Also an FAQ to put in the answer to is my response to claims like the one Bee mentions about seeing string states as a prediction. Very short version: what about M-theory?

  20. Peter, good luck on eclipse day. I’ll be in Gabon. Lots of eclipse maps, including detail maps for Uganda, are on my web site at http://eclipse-maps.com/Eclipse-Maps/Gallery/Pages/Annular-total_solar_eclipse_of_2013_November_3.html For those in the eastern US/Canada/Caribbean, you also get a good show – a partial solar eclipse at sunrise. Details at http://eclipse-maps.com/Eclipse-Maps/Gallery/Pages/Annular-total_solar_eclipse_of_2013_November_3_files/HSE2013_Americas.png

  21. Bernhard says:

    vmarko,

    Here is an old comment from Peter, that I believe addresses your question, to some extent:

    http://www.math.columbia.edu/~woit/wordpress/?p=4065&cpage=1#comment-98564

  22. vmarko says:

    Bernhard,

    Thanks for the link! It took a bit of time to read up the context of that conversation, but now I see. That Peter’s comment should really be put into the FAQ.

    Best, :-)
    Marko

  23. P says:

    Hi Marko,

    Your comment is quite reasonable, though I think it’s safe to say that this isn’t really a new perspective.

    The hope in the 80′s was that there would be a unique string vacuum. Now we know there is a landscape of string vacua — each vacuum comes with a low energy effective action, and things like the gauge symmetry, spectrum, can be computed. People have been viewing the situation this way for at least ten years.

    Cheers,
    P

  24. Tim May says:

    Good luck on your trip!

    I’m enjoying the book you recommended, Frenkel’s “Love and Math.” Some very nice explanations of some abstract math. (As a kid, I loved Gamow’s “One, Two, Three…Infinity” and books of that type. So books like Frenkel’s are a real treasure.)

    I’m slightly less negative about string theory in recent years. I started reading your blog, and then your book, after finding a lot of the string theory, M-theory popular accounts way too “hand-wavy.”

    Also, the hype about string theory seems to have lessened a bit. Unfortunately, the hype deficit seems to be made up for with the hype about the multiverse.

    Nevertheless, I’m looking forward to going to Lenny Susskind’s talk on black holes tomorrow (Tues, 4:15 pm, see site for details) at Stanford. He’s a great speaker, most would agree, and his recent work on the AMPS conjecture doesn’t veer off much into the multiverse stuff.

    –Tim May, California

  25. Peter Woit says:

    I’ve added quite a bit more material to the “Frequently Asked Questions” part of the blog, some of which addresses the question from vmarko, as well as Bee’s comment about string theory being predictive at high energy.

  26. Simple biologist says:

    Peter,

    the new FAQ “Doesn’t string theory make predictions at very high energy?” has a broken link.

    Link on the the words “see this posting” doesn’t work.

  27. Peter Woit says:

    Simple biologist,

    Thanks! fixed.

  28. Bernhard says:

    There is another broken link on “Where and when did news of the Higgs discovery first appear?” (the first one).

    Also, on “Why do you say string theory is unfalsifiable? Doesn’t it predict quantum mechanics?” maybe you could link also to this comment: http://www.math.columbia.edu/~woit/wordpress/?p=5358&cpage=1#comment-136521

    It is the same thing you are saying on the FAQ, but I personally prefer your choice of words on the comment: “The falsifiability criterion is intended to refer to distinctive aspects of a theory that differentiates it from others, not generic properties common to all known theories.”). In fact this whole post + comments are relevant to someone looking into this.

  29. Peter Woit says:

    Thanks Bernhard, I’ve taken your suggestion.

  30. vmarko says:

    Peter,

    “I’ve added quite a bit more material to the “Frequently Asked Questions”…”

    It’s a good read, thanks!

    P,

    “People have been viewing the situation this way for at least ten years.”

    Indeed, as I have just figured out by reading through oldish blog discussions. :-) Apparently this is news only to me. :-) I’ve known about the landscape problem for a long time, and I figured that it was a problem that needed to be solved for ST to work. But only recently have I heard that the “landscape problem” was spinned as a “landscape feature” of ST (outside of the context of multiverse&antropics, that is).

    Apparently I am not socializing with enough string theorists to be in touch with old news. ;-)

    Best, :-)
    Marko

  31. James says:

    While you are in Uganda, you should definitely try make it down to see the Mountain Gorillas in the Virunga Volcano region. (if not in Uganda, then just across the border in Rwanda, where I saw them, and I have heard is a better experience) It’s the experience of a lifetime. The bus trip from Kampala is extraordinary in and of itself. You can, and I might advise to, make reservations ahead of time.

  32. Dan says:

    I don’t know anyone who is optimistic that it will turn out that the 62.5% energy jump in 2015 will find something when the 400% energy jump didn’t

    Well, after all the Higgs discovery at LHC needed a 10-20% energy jump from the previous LEP