Cosmic Background Radiation Question

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

Wasn't it Paul Jones who wrote:

Relativity.

Electromagnetic radiation always travels at the speed of light relative
to any observer. So radiation that set off from the big bang 13.7
billion years ago arrives at the speed of light. In exactly the same way
that light from a star arrives at the speed of light, even if the star
is travelling away from us at half the speed of light.

The speed of the em-radiation is constant, but the speed difference
between source and observer causes the wavelength to be shifted. In the
case of the cosmic background, the red shift is so great that it's gone
right though the visible wavelengths and down into the microwave region.

--
Mike Williams
Gentleman of Leisure

Wasn't it Paul Jones who wrote:

The flash from the big bang wasn't coherent.

At one time the universe was full of incandescent opaque ionised plasma.
Photons were being created randomly by the hot ions, but they didn't get
far because they got absorbed by other ions in the plasma.

As the universe expanded and cooled, it reached a point where the ions
were able to form into neutral atoms (hydrogen and a bit if helium)
producing a transparent gas. Many of the photons that were in flight at
that time, travelling from every point in the universe in every possible
direction, were suddenly free to travel immense distances.

Some of the photons from regions that are now 13.7 billion light years
away from here happened to be pointing in our direction.

--
Mike Williams
Gentleman of Leisure

"Paul Jones" <[Registered users can see links. ]> wrote in message
news:[Registered users can see links. ]...

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

(Remove pants sp*mbl*ck to reply)