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If so, is that energy contributing to the expansion of the universe?

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If so, is that energy contributing to the expansion of the universe?

- #2

Bandersnatch

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No, it's just lost.If so, is that energy contributing to the expansion of the universe?

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What about the conservation of energy?No, it's just lost.

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Bandersnatch

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Energy is not (always) conserved in General Relativity. The pages below have good layman-oriented explanations of the why.What about the conservation of energy?

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

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

- #5

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Good material. But I still can't understand some things.Energy is not (always) conserved in General Relativity. The pages below have good layman-oriented explanations of the why.

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

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

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

"The thing about photons is that they redshift, losing energy as space expands. If we keep track of a certain fixed number of photons, the number stays constant while the energy per photon decreases, so the total energy

Where goes this lost energy?

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

"The Cosmic Background Radiation (CBR) has red-shifted over billions of years. Each photon gets redder and redder. What happens to this energy?"

I didnt understand what really happens.

- #6

Bandersnatch

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Nowhere. It is just lost.Where goes this lost energy?

Conservation laws depend on symmetries. If there's no time-translation symmetry (as with the expanding universe), there can't be energy conservation, so it doesn't make sense to ask where it went - why would it

- #7

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I understood it now. Thank you.Nowhere. It is just lost.

Conservation laws depend on symmetries. If there's no time-translation symmetry (as with the expanding universe), there can't be energy conservation, so it doesn't make sense to ask where it went - why would itneedgo somewhere if there is no conservation law?

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