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I would like to know the ratio of cosmic microwave background radiation to normal radiation in the universe. I am considering cosmic microwave background radiation to include the microwave, and any other radiation that is being emanated from near the "edge of the universe", while normal radiation is radiation emmitted by stars, nebulae, and other sources within the universe (excluding the cosmic microwave background). Since we are in a galaxy, I know that the normal radiation here far exceeds the cosmic microwave background, but I am interested in the "average" value over the universe. For example: total cosmic microwave background radation in the universe / total normal radiation in the universe.

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Measured in what way? In energy density? – adrianmcmenamin Jul 4 '14 at 14:44
Yes, energy density would probably be the best way to measure it. – Jonathan Jul 4 '14 at 15:23
What do you mean by "edge of the universe"? – HDE 226868 Sep 9 '14 at 1:13
@HDE 226868 By "edge of the universe", I am referring to the area where it took so long for the light to reach us that the universe was opaque at this location. – Jonathan Sep 12 '14 at 17:30
@Jonathan: The "area" you are describing is called the surface of last scattering. See cosmic microwave background on Wikipedia. – pabouk Oct 9 '14 at 14:40
up vote 2 down vote accepted

Most of the light energy in the universe is still in the cosmic microwave background (CMB). If you take the CMB map as measured by COBE, WMAP, or Planck and remove the emission from the MW, then you have a map that represents the IR/MW light distribution at a random point in space. This map is strongly dominated by the relic photons. The maps do show lots of point sources, which are the galaxies, but their contribution to the total photon number or energy is small. I do not have exact numbers on this though.

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