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Suekdccia

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- TL;DR Summary
- Matter gaining energy from expanding spacetime?

Sean Carroll has an article (https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/) where he explains that matter can gain energy from spacetime expansion.

At the end of the article, he says: In general relativity spacetime can give energy to matter, or absorb it from matter, so that the total energy simply isn’t conserved.

So, there are natural processes where there is a loss of energy like photons being redshifted from spacetime expansion…

But what about gaining energy? Is there any example of matter or radiation gaining more and more energy as spacetime expands as Carroll seems to suggest?

At the end of the article, he says: In general relativity spacetime can give energy to matter, or absorb it from matter, so that the total energy simply isn’t conserved.

So, there are natural processes where there is a loss of energy like photons being redshifted from spacetime expansion…

But what about gaining energy? Is there any example of matter or radiation gaining more and more energy as spacetime expands as Carroll seems to suggest?