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Gross Tel Aviv perspective on string

  1. May 5, 2007 #1


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    David Gross gave the concluding talk at a recent string conference in Jerusalem and Tel Aviv


    I am having difficulty getting the slides and video, which Peter Woit says are online.

    This talk by Gross (Nobelist, director of Santa Barbara ITP) is likely to be interesting. If anyone has a better link, experiences or figures out the problem, please share what you know.

    Lacking the original video talk by Gross, here is Woit's blog summary of it:

    ==quote from N.E.W.==
    Gross ended the conference with a remarkable discussion of the current state of string theory. He put up various cartoons illustrating the fact that the public perception of string theory has turned rather negative (including the recent one from the New Yorker: “Is String Theory Bullshît?”), but took solace in a recent use of string theory in an advertisement for women’s bikinis. He declared that “I am still a true believer in the sexiness of string theory”, and that he continued to think it is clearly on the right road.

    But, after giving the standard list of string theory achievements, he did admit that he was much less optimistic than 20 years ago, and spent some time discussing what he sees as the main failure to date: the continuing lack of a fundamental dynamical principle behind string theory.

    The question “what is string theory?” still has no real answer, and he has “the very uneasy feeling that we’re missing something big, that semi-classical intuition fails”, and that this will make the landscape disappear.

    Perhaps most remarkably, Gross admitted to some discouragement about AdS/CFT. He noted that the recent Klebanov et. al. results promoted by press release as connecting string theory with physics were actually due to an impressive gauge theory calculation. According to him, what has happened is that gauge theory techniques have proved more powerful than string theory techniques. He went on to discuss the landscape, explaining that he found the anthropic principle impossible to falsify, completely against the way physics has made progress in the past, and just “an easy way out”.

    Gross ended his talk by pointing out that 90 percent of the conference talks used supersymmetry, and that currently there was a “really weird situation”: supersymmetry was an essential tool, but there was absolutely no evidence for it. He said that he continues to believe that supersymmetry will be found at the LHC and has been willing to take 50/50 bets on the subject for bottles of wine, etc.

    more links to try

    Ahh, I see they say that the videos require a Windows system. So Mac users can't get Gross' talk.
    Last edited by a moderator: Apr 22, 2017
  2. jcsd
  3. May 6, 2007 #2


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    No big surprise that gauge theory stands up in the face of adversity. I admit, however, I tend to cling to background independent, diffe-invariant, GR consistent models.
  4. May 6, 2007 #3
    for the video, I have a windows system, but had the same problem (using FF).
    Using IE it worked. Maybe you want to try IE on Mac as well.
    If not, this info might at least be useful to other people WITH a windows system.
    Last edited: May 6, 2007
  5. May 6, 2007 #4
    I can't open with Safari/Mac.

  6. May 6, 2007 #5
    Why "cling" to ideas that are so speculative and in which you're not personally invested?
  7. May 6, 2007 #6
    he found the anthropic principle impossible to falsify

    Gee, I would think that a fundamental dynamical principle that defines the structure of the universe from "non-anthropically constrained" first principles, would accomplish exactly that.

    I swear to "god" that some of the most intelligent people in the world go absolutely brain-dead when it comes to the anthropic physics.
  8. May 6, 2007 #7
    Gross is trying to say that the (weak) fact of our existence can’t be falsified, so the selection principle can’t be falsified, but a fundamental dynamical structure principle necessarily falsifies any possibilty for selection effects.

    The fact that the ’main failure in 20 years’ to produce a fundamental dynamical principle in lieu of “anthropic selection", *most apparently* and only indicates that the anthropic constraint must be strongly linked to any realistically plausible cosmological structure principle, so he has disassociated the dynamical structure principle that is being indicated by the only two relevant facts, while complaining about the solution that is *most apparently* being offered.

    I wonder why?

    Maybe it’s because anthropic selection CAN be falsified in context.
  9. May 6, 2007 #8


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    Good Day!
    I took the time to listen to his remarks and also to some of the other presentations.
    I found that his important message was something else than the anthropic principle.
    1. String has not found the right model that they can use to do dynamics. (to his dissapointment)
    2. He thinks that Supersymmetry does seem to indicate a way to go.
    3. More knowledge of minimum scale and mini black holes would be of helpfull.
    (which CERN should supply)
  10. May 7, 2007 #9

    Hans de Vries

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    Nobel price winner Martinus Veltman concludes his 2003 pop-sci book with:

    That's before Woit started his blog?

    This is from "Facts and Mysteries in elementary particle physics"
    A lovely pop-sci book discussing the SM, its history and its
    personalities including humor and personal anecdotes.

    This is from somebody who excelled in going really deep in real physics.

    Regards, Hans
    Last edited by a moderator: May 2, 2017
  11. May 7, 2007 #10


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    I have heard several times that some branch of physics is "sexy". Can somebody explain to me what does it mean? (I am serious.)
  12. May 7, 2007 #11
    Having the power to attract, pleasing to the mind (I guess). I personally find the term horrible.
  13. May 7, 2007 #12


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    from answers.com
    2. Slang. Highly appealing or interesting; attractive: “The recruiting brochures are getting sexier” (Jack R. Wentworth).
  14. May 7, 2007 #13
    Goodness! I start thinking about a gender critique of ST! Using of a word instead of another one is never accidental... Maybe a woman woundn't use that word... but few women talk about ST. I give you a question: are there more women working on ST or on QG? It isn't so trivial ;-)
    Last edited: May 7, 2007
  15. May 7, 2007 #14
    http://4.content.collegehumor.com/d1/ch6/2/5/collegehumor.5b8042f283aa6f7007d91c25fe4a99a6.jpg" [Broken]
    Last edited by a moderator: May 2, 2017
  16. May 7, 2007 #15

    Hans de Vries

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  17. May 8, 2007 #16


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    They remain attractive having been thoroughly tested and not falsified to date.
  18. May 8, 2007 #17
    Terms like "sexy, promising, or attractive" lose their luster after about 20 or 30 years of stagnation. Maybe they're still the most-sexy and most-attractive things going, but now they have age-spots and wrinkles, so the terminology is essentially nothing but hype at this point.
  19. May 8, 2007 #18
    Science is a human activity (as far as we know), and we humans are most of the time subjective creatures. So, in order not to be deluded most of the time in our subjectiveness (which usually have nothing to do with nature out there), we have trained ourselves with mathematical logic and, among others, constructed the scientific method to guide us. Subjectiveness, however, is good sometimes, it's a human element that sometimes brings forth interesting enlightment. But we should not allow ourselves to be eventually deluded. I might personally find some approach or idea attractive and become interested in spending my time and energy on it. But just because I subjectively "feel" its attractiveness is not a reason to firmly believe it is true.
  20. May 8, 2007 #19
    I do not like this business of sexy branches or not sexy branches. Some like stringy branches, other`s loopy branches. Every branch is a sexy branch to someone (well, maybe not when that branch is a twig). So no more of this talk about sexy branches.
  21. May 8, 2007 #20
    we have trained ourselves with mathematical logic and, among others, constructed the scientific method to guide us.

    I would think that these would be the most natural criteria for defining what physicists should see as sexy physics, rather than being viewed as some un-natural kludge that we've construed to keep us in line with the nature, although it does accomplish this in spite of our prejudices, like you said.

    Natural rigor defines the most preferred theory, which is why their most natural extensions make the "most clean" predictions.

    If the preferred theory is the most accurate reflection of nature in the least number of steps possible, then this natural preference should define "sexy" to a physicist.

    So anything other than the most naturally preferred theory necessarily carries a *greater* degree of deviation away from absolute hotness!... er, perfectly sexy?... ;)

    Something about absolute symmetry as a natural but unattainable "goal".
    Last edited: May 8, 2007
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