- #1
Suekdccia
- 345
- 25
- TL;DR Summary
- What would it mean if all symmetries in physics would not be fundamental?
Physicist Joseph Polchinski wrote an article (https://arxiv.org/pdf/1412.5704.pdf) where he considered the possibility that all symmetries in nature may not be fundamental. He says at page 36:
"From more theoretical points of view, string theory appears to allow no exact global symmetries, and in any theory of quantum gravity virtual black holes might be expected to violate all global symmetries
Moreover, as we have already discussed in §2, local (gauge) symmetries have been demoted as well, with the discovery of many and varied systems in which they emerge essentially from nowhere. It seems that local symmetry is common, not because it is a basic principle, but because when it does emerge it is rather robust: small perturbations generally do not destroy it. Indeed, it has long been realized that local symmetry it is ‘not really a symmetry,’ in that it acts trivially on all physical states. The latest nail in this coffin is gauge/gravity duality, in which general coordinate invariance emerges as well.
This leaves us in the rather disturbing position that no symmetry, global or local, should
be fundamental (and we might include here even Poincaré invariance and supersymmetry).
Susskind has made a distinction between the mathematics needed to write down the equations describing nature, and the mathematics needed to solve those equations. Perhaps symmetry belongs only to the later."
I have a few questions about this:
1. If all symmetries (even the most fundamental ones) would not fundamental after all, would it mean that no laws of physics are really fundamental? If all symmetries and all laws associated with them would not be fundamental, would that mean that literally all laws of physics would not be fundamental but rather emergent?
2. Polchinski has mostly worked on string theory and models related with it. Is it there any type of string theory or any kind of model/theory related with it which proposes that all symmetries may not be fundamental?
"From more theoretical points of view, string theory appears to allow no exact global symmetries, and in any theory of quantum gravity virtual black holes might be expected to violate all global symmetries
Moreover, as we have already discussed in §2, local (gauge) symmetries have been demoted as well, with the discovery of many and varied systems in which they emerge essentially from nowhere. It seems that local symmetry is common, not because it is a basic principle, but because when it does emerge it is rather robust: small perturbations generally do not destroy it. Indeed, it has long been realized that local symmetry it is ‘not really a symmetry,’ in that it acts trivially on all physical states. The latest nail in this coffin is gauge/gravity duality, in which general coordinate invariance emerges as well.
This leaves us in the rather disturbing position that no symmetry, global or local, should
be fundamental (and we might include here even Poincaré invariance and supersymmetry).
Susskind has made a distinction between the mathematics needed to write down the equations describing nature, and the mathematics needed to solve those equations. Perhaps symmetry belongs only to the later."
I have a few questions about this:
1. If all symmetries (even the most fundamental ones) would not fundamental after all, would it mean that no laws of physics are really fundamental? If all symmetries and all laws associated with them would not be fundamental, would that mean that literally all laws of physics would not be fundamental but rather emergent?
2. Polchinski has mostly worked on string theory and models related with it. Is it there any type of string theory or any kind of model/theory related with it which proposes that all symmetries may not be fundamental?