Where did the energy of red shifted CMB go?

[1832vin]

i know it sounds stupid, but i can't seem to find an answer to it

where did the energy went? you can't just just destroy energy, but when you red shift a gamma CMB into a microwave CMB, the energy has go to go somewhere...?
it's not like one gamma photo spitted into many microwave, cause that would make CMB not very smooth

i mean, I've just got no clue, normally, when red shift is from an object, you can say that momenta is given to the object receding or something, but you can't really give energy to space and expect it to do nothing...?
and according to my very rudimentary calculations with a lot of assumptions, the amount of energy lost would still, be not enough to expand space at all, so if it's not expanding space, where did the energy go?

thankyou

 

[Bandersnatch]

you can't just just destroy energy

This is not a universal rule. It only applies to static spacetimes.

See Sean Carroll's blog post linked below for a lengthier response:
http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/

 

[phyzguy]

In general energy is not conserved in General Relativity. So the energy is simply lost.