B Is energy really not conserved in a constantly expanding Universe?

[Question69]

TL;DR

Is energy conserved in GR?

Is energy really not conserved in a constantly expanding universe?

 

[PeterDonis]

The short answer is, it depends on what you mean by "energy" and what you mean by "conserved". Sean Carroll's blog post on the topic is a good place to start:

https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

 

[PeterDonis]

it depends on what you mean by "energy" and what you mean by "conserved".

Credit where credit is due, this bon mot is not original with me, it comes from this Usenet Physics FAQ article, also worth reading:

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

 

[Question69]

The short answer is, it depends on what you mean by "energy" and what you mean by "conserved". Sean Carroll's blog post on the topic is a good place to start:

https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

Oh I've read that already, it was when I first found about it really, I just thought I'd ask you guys because maybe Sean is wrong :)

 

[PeterDonis]

I just thought I'd ask you guys because maybe Sean is wrong :)

Um, no.

 

[PeterDonis]

I've read that already, it was when I first found about it really

That would have been a good thing to mention in the OP of this thread.

Do you have any further questions on the topic?

 

[Question69]

That would have been a good thing to mention in the OP of this thread.

Do you have any further questions on the topic?

I should have, yes, and no.

 

[PeterDonis]

I should have, yes, and no.

I'll take that as "no further questions". Thread closed.