Question69
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- Is energy conserved in GR?
Is energy really not conserved in a constantly expanding universe?
Is energy really not conserved in a constantly expanding Universe?
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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/
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/
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Credit where credit is due, this bon mot is not original with me, it comes from this Usenet Physics FAQ article, also worth reading:PeterDonis said:it depends on what you mean by "energy" and what you mean by "conserved".
https://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html
Question69
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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 said:The short answer is, it depends on what you mean by "energy" and what you mean by "conserved".
https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
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Um, no.Question69 said:
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That would have been a good thing to mention in the OP of this thread.Question69 said:
Do you have any further questions on the topic?
Question69
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I should have, yes, and no.PeterDonis said:
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I'll take that as "no further questions". Thread closed.Question69 said: