do you ever just wonder
where does the energy go from redshifted photons
if a photon of green light at 500 nanometers is emitted and then travels through space for a while, the expansion of the universe causes it to redshift until it's, say, a red photon of 700 nanometers
that's a loss of over an entire electronvolt
where did that energy go?
-F
@CoronaCoreanici does the expansion of the universe take energy? by what mechanism would the energy be transferred from a photon to it?
-F