"Paul Jones" wrote in message
...
Hi,

The following question has been troubling my tiny brain, please could
one of you boffins answer it for me:

If the Cosmic Background Radiation is leftover from the Big Bang,
which is also the source of all the galaxies then, given that almost
all the galaxies are moving away from us, why isn't the CBR also
moving away from us (in which case, according to my underdeveloped
noodle, should mean that we can't detect it)?

Thanks,
Paul

Adding to other explanations, the cosmological red shift (not Doppler shift)
of the microwave radiation is around 1,089, that is the wavelengths are
1,090 times longer than they were when the radiation was emitted (or set
free by the recombination of electrons and protons). So we still see it.
When it was emitted it was optical radiation about the same temperature as a
cool M-type star, but missing the absorption lines of the metals since none
had yet formed aside from a little Li and Be. (maybe a speck of boron).

When recombination occurred the temperature was around 3,000 K; now it is
2.7 K.

--
Mike Dworetsky

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