Conservation of energy in GR (split from universal laws)

[Robittybob1]

 

There are some laws we believe are universal such as causality, various conservation laws, etc. And people constantly develop ever better tests to see if they do hold. But even those "universal" laws have limits; conservation of energy does not apply (in any simple form) in general relativity, for example.

 

 

You probably get a Nobel Prize.

Can anyone give us a quick reminder what happens to the conservation of energy in general relativity please?

It might be worth exploring as a separate topic.

[Strange]

Can anyone give us a quick reminder what happens to the conservation of energy in general relativity please?

It might be worth exploring as a separate topic.

 

The first couple of results from Google:

http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html

http://motls.blogspot.co.uk/2010/08/why-and-how-energy-is-not-conserved-in.html

[Robittybob1]

 

The first couple of results from Google:

http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html

http://motls.blogspot.co.uk/2010/08/why-and-how-energy-is-not-conserved-in.html

Seemed to be a lot questions being asked in both of those references. Maybe there will be an answer since we have had a BH merger.

In that first link can you understand all that they are talking about? There seems a bit of uncertainty expressed in it.

 

So one can argue that "gravitational energy" does NOT act as a source of gravity. On the other hand, the Einstein field equations are non-linear; this implies that gravitational waves interact with each other (unlike light waves in Maxwell's (linear) theory). So one can argue that "gravitational energy" IS a source of gravity.

[Robittybob1]

A thread without any OP statement!

 

What I was wondering was why in GR there was non-conservation of energy? I was told today by Strange that GR did not conserve energy (that's how I took it), as before that I was completely ignorant of that fact (is it a fact?). So here is a chance to increase our understanding of conservation of energy in GR and classical physics in order to understand why there is this difference (if there is any?).

 

Not knowing the facts I can't even be specific in the wording of the OP statement sorry. [bedtime for me. I'll reply in the morning.]

[ajb]

Conservation of energy is something to do with the physics being invariant under time translation. In general relativity, one needs to make sense of this and in general one cannot. In general there is no notion of 'time invariant'. However, for 'nice' space-times you can define energy and momentum. Look up Bondi, ADM and Kormor masses/energy.