Time Symmetry and Matter/Energy Conservation

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Discussion Overview

The discussion centers around the relationship between time symmetry, spatial symmetry, and conservation laws in physics, particularly in the context of Noether's theorem. Participants explore how these symmetries relate to the conservation of energy, matter, momentum, and angular momentum, as well as the implications of these relationships.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that time symmetry is fundamental to all conservation laws as stated in Noether's theorem, linking it to the conservation of matter and energy.
  • Another participant corrects this view, stating that time symmetry is relevant only to the conservation of energy and mass, while spatial symmetry is responsible for the conservation of momentum and angular momentum.
  • A later reply emphasizes that Noether's theorem applies to various conservation laws, each associated with its own symmetry principle, suggesting that it is inappropriate to generalize one symmetry principle across all conservation laws.
  • One participant expresses confusion over the terminology used, specifically distinguishing between "time symmetry" and "underlying symmetry," seeking clarification on their distinct roles.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are competing views regarding the applicability of time and spatial symmetries to different conservation laws. The discussion remains unresolved with respect to the clarity of terminology and the implications of Noether's theorem.

Contextual Notes

There are limitations in the discussion regarding the definitions of time and spatial symmetry, as well as the specific conservation laws they relate to. The nuances of Noether's theorem and its implications for different conservation laws are not fully explored.

Rodney Flores
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I recently posted a question on energy and matter and I got a very good answer to that one so I thought another one wouldn't hurt. I understand that time symmetry is what makes all conservation laws possible as is stated in Noether's theorem. Time symmetry is what explains the conservation of matter and energy and in part also unifies the two. Because time symmetry doesn't change the way it works, and energy and matter do, would the symmetry of space not change as well?
 
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Rodney Flores said:
I recently posted a question on energy and matter and I got a very good answer to that one so I thought another one wouldn't hurt. I understand that time symmetry is what makes all conservation laws possible as is stated in Noether's theorem. Time symmetry is what explains the conservation of matter and energy and in part also unifies the two. Because time symmetry doesn't change the way it works, and energy and matter do, would the symmetry of space not change as well?

Er.. correction. The time symmetry is relevant to NOT ALL conservation laws, only the conservation of energy+mass!

The spatial symmetry is responsible for the conservation laws we see for momentum (and angular momentum if you include space anisotropy).

Noether theorem applies to not just energy conservation. It simply states that in the most general form, every conservation laws implies an underlying symmetry. So each conservation law has its own symmetry principle. You should not use one symmetry principle for all conservation laws that might not be appropriate.

Zz.
 
Well, considering my dislike for wikipedia (can you guarantee that would be the same information next month?), here's a more established reference:

http://xxx.lanl.gov/abs/physics/9807044

Zz.
 
oh no my mistake, I said "time" symmetry and when I really ment "underlying" symmetry, exactly in the sense in which you have stated Zapper (the underlying symmetry of every conservation law). Sorry for the confusion, so there is "spacial symmetry" as you have stated, is it distinct from time symmetry? (Thank you for the sources) :)
 

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