CMB energy

[Jarek Rzepecki]

On Tue, 24 Feb 2004, Bartosz Lew wrote:

> The correct answer is: Nothing happened to that energy. It's still there
> (unless photons gets older or other crap like that), the only thing that 
> changed is that we no longer see hot photons because, as we've been tought 
> in high school, we're floating away from everything else according to the hubble law.
> (So the answer is essentialy in the question ;)
> The "doppler effect" which can easily be derived from SR transformaiton
> formulas causes  that we see everythig red. The only difference from the
> situation described above with observers looking at identical photons (and
> yet seeing them in different colors) and
> complication I see here is that it is not possible to find a recerence frame
> in which we will see the whole CMB photons at different temperature - color
> etc. This is of course because it's the space that expands and there is nothing
> we can do about it, so changing reference frame won't help in understanding
> that it is just our obserwational effect not a true energy theft by some
> more less unidentified process. But still I belive that  this reddening can
> be ballanced once when Universe start to collapse.

Well I think that the problem is closer to the question: Why photons 
getting out of potential well suffer from red-shift - where their energy 
go in that case? then to the Doppler...