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No-frill unification bid to replace string

  1. Dec 13, 2009 #1

    marcus

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    This is a movement we are seeing take shape now. It involves recent work by Shaposhnikov and Wetterich, by Meissner and Nicolai, by Steven Weinberg, by Roberto Percacci, and by others.

    The clearest statement so far was by Hermann Nicolai in his talk at the Wroclaw July 2009 Planck Scale conference. H.N. repeatedly used terms like "economy", "minimalistic", "Occam", "austerity", "spartan".
    He contrasted his type of approach to string phenomenology, which he called "increasingly Baroque", and to nonminimal extensions of the standard model ("NMSSM") which he said "pay a heavy price in terms of economy". He described the direction of his approach as "the opposite of F-theory".

    The aim which H.N. laid out and recalled repeatedly was to delay breakdown of the standard model past the Planck limit (about 1015 TeV), with few if any additional moving parts to the theory, and to make testable predictions.

    The "big desert" hypothesis could be true, namely that there is no new physics needed between the weak scale and the Planck scale. In that case this kind of theory could apply.
    I have to go, back later.
     
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  3. Dec 13, 2009 #2

    marcus

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    No-frill unification is being pursued by a growing bunch of theorists. That doesn't mean it's right. We don't know what will eventually turn out to be right. It is just how the wind is blowing.

    Steven Weinberg is a kind of bell-weather indicator. In July 2009 he gave a talk at Cern (opening a big particle theory conference) where he said he didn't want to discourage any of the string theorists but string might not be the way the world is, and might not be needed.

    In fact he sketched the no-frill unification program right there---unification within the context of something very close to "good old quantum field theory"---described the renewed interest in asymsafe gravity and his own new research direction (no-frill early-Universe cosmology).

    Then later in October 2009 he gave a talk to the national convention of science writers. It was a 40 minute overview of particle physics and what to expect from LHC. He did not mention "string" once during the whole talk. At the end someone in the audience asked what about string. Weinberg described it as having been a "disappointment".

    He said his own research had taken a different direction.

    Have to go again, back later.
     
  4. Dec 13, 2009 #3

    apeiron

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    It is hard to keep track of all the new movements you keep identifying. But great that you do.

    Is there a general division we can make across these movements that identifies some as starting with the objects (strings, loops, knots) and looking for the relationships to emerge. While others are starting with the relationships and looking for the objects to emerge (condensed matter, gauge symmetry)?

    I know this would be a rough division as every camp has something of both. But does this sound like one of the things that is going on?
     
  5. Dec 13, 2009 #4

    marcus

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    Apeiron,
    what I'm trying to do here is arrive at a comprehensive overview of what ALL the most active approaches represent. The comment elements and directions shared by all.
    And what is very important to realize is that individual researchers are not divided into CAMPS!

    For example, Hermann Nicolai is a prominent string theorist. Perhaps Europe's most influential string theorist. He obviously thinks that no-frill unification is worth pursuing. And he frankly points out the failures of string. But he will continue to do string research and to write articles spotlighting progress in applying stringy math! He is not in a CAMP. Indeed he has been on the governing committee of each annual String conference for 9 or 10 years and he directs an institute near Berlin that has a lot of string theorists in it (and also loop, simplicial, and group field theory, but probably majority string).

    But Nicolai has so far been the most articulate proponent of the no-frills program. Anyone who has not listened to his Wroclaw video should definitely listen. It is a really clear, really strong statement of the no-frill unification rationale and goals.

    The general no-frill thrust is RELATED but not identical with the recent work in asymptotic safety that you see in papers by
    Roberto Percacci
    Shaposhnikov and Wetterich
    Steven Weinberg

    But notice that Nicolai and Meissner's proposal has nothing at all to do with asymsafety!

    What I'm trying to do is identify the overall theme. Making do with the Quantum Field Theory framework, out to (say) quadrillion TeV.
    Making do with the SM+gravity.
    *No low-energy supersymmetry
    *No GUT
    *No new physics between weak scale (less than 1 TeV) and planck scale (roughly 1015 some TeV)

    Shifting the Landau poles out way past Planck, delaying any and all breakdowns and blowups.

    As Weinberg said in his July CERN talk, string theory might not be needed! It is a conservative minimalist attitude. Maybe gravity (which seems to be renormalizable after all) and the standard model are sufficient. I will get some links:
     
    Last edited: Dec 13, 2009
  6. Dec 13, 2009 #5

    apeiron

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    Thanks for your opinion on that. Though I don't see a real problem in different approaches existing and individuals having a foot in several.

    But what about the question I posed on objects => relations vs relations => objects?

    Or if we were perhaps to use the terminology of category theory, the division into structures and morphisms?
     
  7. Dec 13, 2009 #6

    marcus

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    Apeiron, what if ever since 1980 we didn't need any new objects and just didn't realize it.
    What if all the creativity since 1980 was wasted effort?
    What if the framework, after all, is some variant of 1915 gravity (quantized) and our familiar QFT with its well established SM?
    What would you call that? Is that objects or is that relationships? Or does it matter?

    BTW how would you classify LQG? Remember Rovelli's definitive seminar talk where he says that LQG does not start with objects. Loops or foams or simplices or spin networks or the more basic holonomy flux algebra are all just different ways to calculate relationships among measurements. He is explicit about that. So would you classify LQG as relational or object based? Applied to LQG I do not see that your division makes any sense.

    But let's try to focus on the no-frills trend in theoretical physics research. Let's concentrate and not try to pigeon-hole it immediately.
     
    Last edited: Dec 13, 2009
  8. Dec 13, 2009 #7

    marcus

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    I promised to get links. These people can be considered as early spokesmen for the no-frill direction in research,

    Nicolai video and slides PDF here:
    http://www.ift.uni.wroc.pl/~rdurka/p...ndex-video.php [Broken]
    If there is a movement, Nicolai's talk is the manifesto.

    Outstanding paper by Shaposhnikov and Wetterich
    http://arxiv.org/abs/0912.0208
    Asymptotic safety of gravity and the Higgs boson mass
    "There are indications that gravity is asymptotically safe. The Standard Model (SM) plus gravity could be valid up to arbitrarily high energies..."
    Seeing this S&W paper is what tipped it for me. It isn't Nicolai, it isn't Percacci, it isn't Weinberg, but it is LIKE them. It shares a common thrust.
    Here's a thread about it:
    https://www.physicsforums.com/showthread.php?t=359575

    Thread about Percacci's "GraviGUT" paper. Using SM and asymsafe gravity to get unification.
    https://www.physicsforums.com/showthread.php?t=349513
    Here's the paper:
    http://arxiv.org/abs/0910.5167
    Gravity from a Particle Physicist's perspective
    "... There are thus reasons to believe that quantum field theory may eventually prove sufficient to explain the mysteries of gravity."

    Thread about Weinberg "string disappointment" talk
    https://www.physicsforums.com/showthread.php?t=347140
    The talk (string not mentioned until audience question at end):
    http://www.ustream.tv/recorded/2384517

    Weinberg CERN talk about the QFT revival and new asymsafety interest
    http://cdsweb.cern.ch/record/1188567/
    To save time jump to minute 58, the last 12 minutes.
     
    Last edited by a moderator: May 4, 2017
  9. Dec 13, 2009 #8

    apeiron

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    Yes, these would be the kind of broad-brush questions that might be able to prevent wasted effort.

    People replaced little billiard balls with strings and loops and knots. It still sounds a good approach. Identify a cannonical object and see what results.

    Even if the question cannot be answered, I - like you - find it interesting to classify what is going on in science.

    That is what prompted the question. I am not sure how it would fit the particular classification scheme I had in mind. Though relativity and field approaches would sound relational to me.

    Again, this was a key reason for liking the general tone of loops. It seems to be promising a successful mix of both the object view and the relational view. Which is what I myself would expect from a systems standpoint.

    So if there is this new horse riding into the race as you identify, I'm curious as to whether it is a return to what I would see as a more purely relational approach.

    We all have a right to our own interests surely?

    It could be that you think object~relation or structure~morphism is simply the wrong lens to apply for some concrete reason. Or you just might prefer some other better way of looking at things. Or you may prefer to be agnostic.

    The actual division you cited here, from Nicolai, is framed as no frills vs baroque. And of course science modelling should always be as simple as possible (but no simpler).

    It also seems likely that a final theory in terms of just one side of things - either the objects or the relations - would have to be simpler than any theory that attempted to mix the two.

    But the question then is whether a monadic theory coming from either side (either the object-centric or relational) is going to always be "too simple". Perhaps only a well-balanced approach, like potentially loops, can work as it sits more in the middle of these two conceptual poles.

    That is my own thinking and sorry if you find these intrusions unhelpful.
     
  10. Dec 13, 2009 #9

    marcus

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    I certainly find this last post #11 quite helpful. I need the tension of some disagreement and will study what you say and reply as time permits. We are having a small all-day christmas party with fire, eggnog and just the right people!

    I apologize for giving the impression that I thought your dichotomy unhelpful. Retract! Retract! it is not an intrusion, it is more of a conceptual challenge.
     
    Last edited: Dec 13, 2009
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