QC0086: Prof. Louis H. Kauffman: Knots And Quantum Field Theory, QAD

This is the QA&D session following Prof. Louis H. Kauffman's presentation (QC0085) on the subject of Knots, Quantum Field Theory, and how these mathematical formulations relate to the physics of particles.

Recorded: 2020 07 05 at 10 28 GMT 7

[Achrononmaster]

@24:00 I'll be in the front ranks to diss String Theory but you guys seem a bit mislead by YouTube for heavens sake. Perhaps read some papers or Polchinski's free online book? Electrons, photons, gravitons in String Theory arise from the spectrum of fundamental modes once you quantize the classical string. It's just Fourier expansions essentially, their labels (spin, mass, etc) are quantized. So any m=0, s=1 mode is your photon, m=0, s=2 is your graviton. It's not "billions of vibrations" (since it's QM you would have to consider superpositions, but it's not the superpositions giving the spectrum of modes). Also, the ~10⁵⁰⁰ different S-Theories is incorrect, there is only one unique String Theory, but it has a vast number of possible vacuum states (Calabi-Yau spaces). So it is the _solutions_ that are too numerous. The problem is whether our universe only has one vacua or a dynamical vacua, if the former how to find it experimentally, since theoretically several vacua could give almost the same phenomenology. Theory thus cannot _alone_ find the vacuum CY, you'd need experiment. So it seems hopeless with present day technology.
If you ask me, the philosophical problem with String Theory is it lacks parsimony, it's like ordering a plate of the first 100 primes, and the waiter handing you a bucket of the first quadrillion Natural numbers. Give me enough degrees of freedom and I can find you some valid physics in the mix, satisfying Lorentz invariance and unitarity, nice gauge groups, &c., ... plus a whole lot of other garbage. Ptolemaic epicycles in other words. Many string theorists ignore this, they think String/M Theory is so highly constrained it is unique, and they are right about that, but this is only what I would call gauge or static uniqueness, the problem is the dynamics: the dynamics allows far too much that we do not observe. Possibly we will observe more in future to lend M-Theory more validity, but even before checking dynamics there is supersymmetry (none of it found!) which at the moment seems like it's going to be the killer. Am I wrong (check back in 20 odd years)?