I Models where all symmetries would be approximate?

[Suekdccia]

TL;DR Summary

Models where all symmetries would be approximate?

I found this interesting discussion here in Physics Forums (https://www.physicsforums.com/threads/are-all-symmetries-in-physics-just-approximations.1005038/) where the topic of all symmetries being approximate is discussed

Is there any model (for instance, some type of spacetime metric or geometry) compatible with our current understanding of physics where all known fundamental symmetries of nature (Poincaré, Lorentz, CPT, translational and internal invariances) would be approximate?

 

[ohwilleke]

There are some models where one or some fundamental symmetries of Nature are violated (e.g. small Lorentz invariance violations are possible in some theories of quantum gravity such as here).

But, while I am not omniscient, I am not aware of any widely studied models in physics in which all known fundamental symmetries of Nature are approximate. I have never seen a preprint or published physics paper or even a blog post by a physicist describing such a model, despite reviewing preprints on more or less a daily basis for at least a decade.

Observational tests strictly limit the extent to which reality can deviate from these symmetries. But, of course, the conceptual leap of faith from a very close approximation of an exact symmetry to an exact symmetry can never be definitively proven with an observational test alone. This is because all experimental observations have some uncertainty, however slight.

When there is a well motivated theory about why some particular fundamental symmetry might not hold true, scientists will often devote substantial resources to doing particularly precise tests looking for violations of a fundamental symmetry. And, of course, in situations where such violations are discovered (e.g. the separate conservation of mass and energy, rather than merely the conservation of mass-energy) we stop calling that a fundamental symmetry anymore. So, unless you are a historian of science you don't notice those.

But at some point, Occam's Razor comes into play disfavoring elaborations of physical theories in these fundamental symmetries are not exact but are indistinguishable observationally from theories that are exact, without providing some other explanatory benefit.