>>Mike,
>>
>>I would answer in the same fashion: what is the wavelength you are interesting? If it is the quantity measured in the observer's frame, then it is consistent with the frequence measured there. But if it is about "real" wavelength from the absolute frame, then - not.
>
>So you're saying that from the absolute frame there is no loss of energy in expansion?

Energy of what? My comments went to the energy of the light only, and it is not quite clear (for me) what else could be derived from here.

>
>But isn't the whole point of Einstein (or Mach, or others) that the absolute frame is not what is real, and that science is mainly concerned with relative reference frames?

"Real" and "relative" are mostly words related to our ability (not concern) to measure or intrepret what we observe. Yes, there are some intriging and not clearly explainable observations about universe, like that universe is expanding with the speed increasing with the distance. And probably here is a need to include "black/hidden energy". Sorry, I cannot add here anything more.