Is time and space truly symmetric in light of Noether's theorem?

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Discussion Overview

The discussion revolves around the symmetry of time and space in the context of Noether's theorem, exploring the implications of symmetries in physical systems and their associated conservation laws. Participants question the nature of these symmetries and their relevance to concepts such as the conservation of information.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether time and space are symmetric and expresses uncertainty about the meaning of symmetry in a physical context.
  • Another participant explains that a system is symmetric if it remains invariant under certain transformations, introducing CPT symmetry as a fundamental example.
  • It is noted that Noether's theorem establishes a correspondence between symmetries and conservation laws, with energy conservation linked to time invariance.
  • A participant mentions Lorentz boosts in Minkowski space-time as a potential connection to the symmetry of time and space.
  • There is confusion expressed regarding the conservation of information law and its relation to black hole theory, with a reference to the "black hole war" over information loss.
  • One participant seeks clarification on the conservation of information, asking if it relates to Liouville's theorem.

Areas of Agreement / Disagreement

Participants express differing views on the nature of symmetry and its implications, particularly regarding the conservation of information. The discussion remains unresolved with multiple competing perspectives on these concepts.

Contextual Notes

Some statements rely on specific definitions of symmetry and conservation laws, which may not be universally accepted. The discussion includes references to theoretical concepts that may not be fully explained or agreed upon by all participants.

JayJohn85
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Is time and space symmetric? Or am I misunderstanding symmetry in the physical sense? Also according to noether theorem you'll get corresponding conservation laws to the symmetries which prompts the question of what is symmetrical to the conservation of information law.
 
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Some aspect of a system is symmetric if that aspect of the system remains invariant under some transformation. The most fundamental symmetry is CPT symmetry.

Charge (C) - Does the system remain unchanged if we change the sign of the system's charge?

Parity (P) - How does the system change if we change the sign of a single spatial coordinate?

Time (T) - Does the system change if time were reversed?

As far as we know, all systems obey CPT symmetry. To answer your question, we would need to see whether a system has some sort of symmetry associated with it. If a system remains invariant with respect to time, say, then that system has a symmetry associated with time.

Noether's Theorem makes a 1-1 correspondence between conservation laws and symmetries. For example, energy conservation is due to the time invariance of systems. As for "conservation of information law". If this is the law that Dembski proposed, he is full of crap. His reasons for proposing such a law is his opposition to biological evolution.
 
JayJohn85 said:
Is time and space symmetric?
One of the isometries of Minkowski space-time is a Lorentz boost, which "mixes" time and space coordinates. This is as close a thing that I can think of relating to what you said.
 
Thanks for the replies some really good patient people here.

Though having said that I am confused once again. Isn't that law that Dembski proposed used in black hole theory I aint so sure but wasn't the black hole war fought over the whole loss of information thing?
 
JayJohn85 said:
Is time and space symmetric? Or am I misunderstanding symmetry in the physical sense? Also according to noether theorem you'll get corresponding conservation laws to the symmetries which prompts the question of what is symmetrical to the conservation of information law.
So, Noether's theorem relates differential symmetries in the Lagrangian to conserved quantities. The fundamental Lagrangians that we know about all seem to have certain symmetries. One is that they do not change with shifts in time, this leads to conservation of energy. Another is that they do not change with shifts in space, which leads to conservation of momentum, and so forth.

I am not sure what you mean by conservation of information. Are you referring to Liouvilles theorem?
 

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