- Poprzednia wiadomość (według wątku): poprawienie do listy uczestnikow ,,Wszechswiat: globalisci vs antyglobalisci"
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CMBR is almost perfectly well described by u(\ni) d\ni function - the plack function which is the spectral energy density described with the only parameter - temperature. Expansion changes the overall CMBR energy (as we see it) like (1+z)^4 which comes from 4'th power T relation when we integrate u(\ni) d(\ni) (to get Stefan boltzmann law) ( and there is stright relation between temperature of boson gaz with it's enery - alghough coefficients are different in classic and ultra relativistic regime). Bosons are particles which participe positivly to universe's density and pressure thus they only make expansion slower, hence IMHO it's incorrect to say that "it takes some energy to expand the Universe..." nor that the expansion is derived by it's contents. In fact we don't know why BB happened. In fact we don't even know if it happened. (although the expansion rate is altered by the contents in various ways). Recalling the energy density doesn't help much for the question since there still remains 1+z factor left to explain. It's the question why photons suffer from redshift? And is the fact that different observers see, say two identical photons (each of them observes his own photon) as two different photons actually a manifestation of violation of energy conservation principle? I've been thinking about this problem yesterday and what I concluded is... shocking simple. :) IMHO 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. I hope that helps. regards bartek On Mon, 23 Feb 2004, Jarek Rzepecki wrote: >Hi all,>CMB photons are red-shifted due to Universe expansion -> this means that>the whole CMB energy gets smaller... where does it go?>pozdrawiam>Jarek>>

- Poprzednia wiadomość (według wątku): poprawienie do listy uczestnikow ,,Wszechswiat: globalisci vs antyglobalisci"
- Następna wiadomość (według wątku): CMB energy
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