Comments by "N Marbletoe" (@nmarbletoe8210) on "Did String Theory fail? | Brian Greene and Lex Fridman" video.

  1. ​ @pilot.wav_theory  In the case of the quark gluon plasma, apparently we don't know if QFT would produce the same results because the calculations were far too difficult without the AdS/CFT trick from string theory. (source: youtube video lecture by Dam Son, U Chicago, titled Viscosity, quark gluon palsma, and string theory)
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  2.  @pilot.wav_theory  Sure, but still, string theory is testable. A new theory has to pass two types of test: 1) does it agree with previous theory where that previous theory is right and 2) does it predict things that previous theory does not. I gave an example of type 1, but there are also many possible type 2 tests. It is a very constrained theory.
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  3.  @pilot.wav_theory  by "possible" i meant in theory lol. like the 10 spatial dimensions is a strong prediction, but hard to test. also fuzzballs have a non thermal spectrum, and no singularity, unlike the usual black holes
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  4.  @Raging.Geekazoid  Unless they are all real
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  5.  @DivineRedwood  Two results: reproduced the black hole entropy by counting microstates of a fuzzball; predicting the properties of the quark gluon plasma
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  6. one of string theory's big advances is Ads/CFT correspondence
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  7.  @DestroManiak  Sure, you're right, but the stringy people also know you're right, right? Wasn't AdS/CFT used to predict the viscosity of the quark gluon plasma? I'm a novice but I hear rumors of these things...
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  8.  @TB-ni4ur  String theory predicted the viscosity of the QGP
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  9.  @TB-ni4ur  The plasma prediction was an application of string theory to physics.
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  10.  @TB-ni4ur  String theory was applied to predict the viscosity of the quark gluon plasma.
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  11.  @TB-ni4ur  Oh, were you asking about how it can be used to make technology? idk. The plasma prediction does not show the theory is true, but it does show that it has some relationship to the physical world. It's not just weird math, it may be weird math that is sometimes useful.
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  12. have you heard of AdS/ CFT?
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  13. it can be tested but not directly
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  14.  @brianlaudrupchannel  Right now, string theory can use AdS/CFT correspondence. By using this curious theorem, string theory correctly predicted the properties of the quark gluon plasma at CERN and RHIC. I'm no expert, I just heard about this and have watched a video or two...
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  15.  @brianlaudrupchannel  Also String Theory requires 11 dimensions and supersymmetry.
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  16.  @brianlaudrupchannel  right, it requires 11D for the math to be consistent. cheating is allowed.
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  17. ... and to the point of testability, it ONLY works in 10, not in 9 8 7 6 5 4 3 2 or 1 or 12 13 etc (apparently this is due to requiring the theory to be coordinate invariant like GR)
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  18.  @pilot.wav_theory  The question (OP) was if it was testable.
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  19.  @destroya3303  Yup, if we're cheating we have to call it math String theory is a gigantic ball of math. It may be also physics. If so, this could be purely due to chance. Or, maybe everything is a string. This basic idea that everything is a string is eventually falsifiable, probably. Even if it's just a ball of math, it is already useful math for physics!
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  20.  @dinobotpwnz  Good example! String theory correctly predicted the properties of the quark-gluon plasma using a duality.
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  21. quantum mechanics needs 28 constants...
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  22. it is still a big area of research it predicted the quark gluon plasma properties
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  23.  @TheSwamper  All 10^500 versions require is a certain number of dimensions. So they are all testable if we can count the dimensions of reality, right?
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  24. roughly planck scale
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  25. It only works in very specific number of dimension, due to mathematical consistency. No expert but that's what they say.
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  26. ​ @ntf5211  Yeah but that actually means the theory is testable, right?
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  27.  @pilot.wav_theory  Ah so but in the case of the QGP the string math was LESS complex! Lattice calculations can be hard, they say. I'm no expert; algebra is complex to me. But the real point is that LHC measured some QGP, and string theory and lattice QCD both passed the test. They both might have failed, thus, they are both testable. Apparently fuzzballs are very different from black holes; they have no singularity and their Hawking radiation is not thermal. But their math is indeed very complex.
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  28. It predicted the viscosity of the quark gluon plasma before LHC produced the plasma
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  29. it is very falsifiable
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  30. foundational= theoretical experiment = experimental
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  31.  @paulthomas963  they didn't produce some at Brookhaven/ PHENIX?
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  32. quark gluon plasma
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  33.  @ntf5211  String theory is testable by objective experiment.
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  34.  @originalsinquirls1205  String theory predicts supersymmetry, which is testable. It predicted the quark gluon plasma was a liquid not a gas, which was confirmed by CERN.
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  35. The attraction wasn't mathematical simplicity, but conceptual.
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  36. CERN has only been able to look for the very lightest SUSY particles.
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  37. nobody knows why mass-energy curves spacetime, but if you say it does the math works really well and you get a great theory
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  38.  @brianlaudrupchannel  They were not added randomly. 11 dimensions is the only number that keeps the theory coordinate invariant. (10 space +1 time).
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  39. i think that the membranes or branes are actually made of open strings... not sure tho
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  40. it was tested
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  41.  @Eris123451  String theory and CERN are not mutually exclusive. String theory predicts supersymmetry (although it is not the only theory to do so). It also predicted correctly the quark gluon plasma properties as measured at CERN.
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  42.  @Raging.Geekazoid  Maybe. Susskind treats the theory as you suggest -- that it predicts the existence of all the possible universes. Eternal inflation is one name for how they fit together and interact.
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  43. String theory predicted the viscosity of the quark gluon plasma produced at LHC, before it was ever produced
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  44. it is testable
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  45.  @ntf5211  string theory predicted the viscosity of the quark gluon plasma
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  46. it predicted the quark gluon plasma's viscosity
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  47. it predicted the viscosity of the quark gluon plasma
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  48.  @lordofentropy  Wow it failed the cosmo constant, interesting!! But it did get the viscosity correct. Thus, it took TWO tests, one failed and one passed. I'm not saying it's correct, only that it is being tested, and it seems you agree?
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  49.  @lordofentropy  You are saying it WAS tested, and failed. So it was testable.
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  50. if we can say exactly their location, their momentum becomes infinitely uncertain
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  51. a theory is simply a set of hypotheses that work together
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  52.  @tomasxfranco  I understand that many non scientists think of it that way, but that's not the way the term is used in science (edit: in my experience in zoology) Newton's theory of gravity is now known to be wrong, but it is still called Newton's theory of gravity.
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  53.  @ntf5211  Sure, fair point, it's still correct in the limit of low relative velocities. I"m just saying that the term theory can be a good term for an idea if the idea is right, wrong, or unknown, as long as the idea is testable with scientific methods. (by "idea" I mean "a set of causal hypotheses that work together to explain part of nature" --a scientific theory)
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  54.  @atraxisdarkstar  String theory's SUSY particles would be high energy, beyond current LHC range
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