Is the energy from redshifting lost or destroyed?

Question

In cosmological redshifting, photons lose energy because of the expansion of the universe.

Bur what actually happens to this energy? Is it just “lost” or is it physically destroyed (which would seem impossible)? If it is lost, what is it lost to or what does it become?

In: 258

Answer 1

It is essentially lost. Conservation laws are tied to symmetry. In a universe that is expanding, there is a violation of symmetry. This allows for energy to not be conserved. You could think about it as the energy being diluted, but that is probably a poor analogy when you get into the details.