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I have a question for those more knowledgeable about physics: Everything we know so far points to time invariance * , right? What would happen if we discovered

by rland 7y ago

I have a question for those more knowledgeable about physics: Everything we know so far points to time invariance * , right? What would happen if we discovered that some things truly aren't time invariant? Would it crucially change the fundamental understanding, or would it just be a new class of phenomena? * except maybe TFA which isn't really right based on the other comments I'm reading.

lidHanteyk 7y ago
It would substantially reject a lot of assumptions that we normally not just take for granted, but require as part of the restrictive structure that shapes our models. In particular, time invariance is linked via Noether's Theorem to conservation of energy, and thus via Einstein's work to conservation of matter. Indeed, the modern version of time invariance, CPT symmetry, is as weak as it can be while still maintaining this connection. If CPT symmetry were to fail, then we would need to go find new mathematics and new mechanics. For this reason, we test it constantly; see [0] for an overview. [0] https://en.wikipedia.org/wiki/Modern_searches_for_Lorentz_violation https://en.wikipedia.org/wiki/Modern_searches_for_Lorentz_vi...
Enginerrrd 7y ago
Not at all a physicist, but I think I can take a stab at this. I think so far we only see CPT (charge, parity & time reversal) symmetry as being a fully unbroken symmetry of nature within the context of what you're asking. (I believe the weak force breaks a simple time reversal symmetry.) Time symmetry is typically synonymous with energy conservation in classical mechanics. It get's more complicated when you introduce quantum mechanics, and lorentz invariance from relativity. In essence though, there's probably an analogous invariant to energy conservation for CPT symmetry. Maybe this is just lorentz invariance for a quantum field theroy? Not quite sure. Implications of seeing that symmetry broken would be huge since the CPT theorem implies that a quantum field theory obeying lorentz invariance obeys a CPT symmetry. (I'm guessing by an application of Noether's theorem?) SO a violation of that would be either a violation of lorentz invariance (which would be VERY interesting) or some type of violation of the assumptions of quantum field theory. In essence, it would mean new physics!
discreteevent 7y ago
There's a book about this called "The singular universe and the reality of time" by a physicist and a natural philosopher. They think that if we take time as real (not emergent) and irreversible then it could help resolve some of the problems in physics. Like for example the fact that the multiverse theory is untestable. They also emphasise that mathematics (which is reversible) is just a really powerful tool. But it's not reality and modern physics has somewhat mistaken the map for the territory. https://en.m.wikipedia.org/wiki/The_Singular_Universe_and_the_Reality_of_Time https://en.m.wikipedia.org/wiki/The_Singular_Universe_and_th...

by rland 7y ago

lidHanteyk 7y ago

It would substantially reject a lot of assumptions that we normally not just take for granted, but require as part of the restrictive structure that shapes our models. In particular, time invariance is linked via Noether's Theorem to conservation of energy, and thus via Einstein's work to conservation of matter. Indeed, the modern version of time invariance, CPT symmetry, is as weak as it can be while still maintaining this connection. If CPT symmetry were to fail, then we would need to go find new mathematics and new mechanics. For this reason, we test it constantly; see [0] for an overview. [0] https://en.wikipedia.org/wiki/Modern_searches_for_Lorentz_violation https://en.wikipedia.org/wiki/Modern_searches_for_Lorentz_vi...

Enginerrrd 7y ago

Not at all a physicist, but I think I can take a stab at this. I think so far we only see CPT (charge, parity & time reversal) symmetry as being a fully unbroken symmetry of nature within the context of what you're asking. (I believe the weak force breaks a simple time reversal symmetry.) Time symmetry is typically synonymous with energy conservation in classical mechanics. It get's more complicated when you introduce quantum mechanics, and lorentz invariance from relativity. In essence though, there's probably an analogous invariant to energy conservation for CPT symmetry. Maybe this is just lorentz invariance for a quantum field theroy? Not quite sure. Implications of seeing that symmetry broken would be huge since the CPT theorem implies that a quantum field theory obeying lorentz invariance obeys a CPT symmetry. (I'm guessing by an application of Noether's theorem?) SO a violation of that would be either a violation of lorentz invariance (which would be VERY interesting) or some type of violation of the assumptions of quantum field theory. In essence, it would mean new physics!

discreteevent 7y ago

There's a book about this called "The singular universe and the reality of time" by a physicist and a natural philosopher. They think that if we take time as real (not emergent) and irreversible then it could help resolve some of the problems in physics. Like for example the fact that the multiverse theory is untestable. They also emphasise that mathematics (which is reversible) is just a really powerful tool. But it's not reality and modern physics has somewhat mistaken the map for the territory. https://en.m.wikipedia.org/wiki/The_Singular_Universe_and_the_Reality_of_Time https://en.m.wikipedia.org/wiki/The_Singular_Universe_and_th...