Follow
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
@Felthry Into that expansion.
@CoronaCoreanici does the expansion of the universe take energy? by what mechanism would the energy be transferred from a photon to it?
-F
@Felthry ...fuck, this is gonna keep me up.
i have been told that it actually does just go away, because the universe taken as a whole is not time-symmetric and thus conservation of energy does not apply by Noether's theorem
i have also been encouraged to look at some videos pbs spacetime did about this so i will look into those tomorrow probably because right now it's late
-F