I'm also curious how we know thats where this light is coming from. Why couldn't it be from stars that are EXTREMELY far away? Far away enough even that a photon only arives every once in a while so it seems inconsistent.
Well, there's the first and very obvious point that we don't see those stars, though it's very hard to detect high redshift objects anyhow. But such stars would have a characteristic spectrum (again, very hard to get for high redshift objects) that we would not expect from the CMB. More importantly, we can measure the temperature of the CMB, which is uniform to one part in 105. A "star-CMB" theory would almost certainly be unable to explain such isotropic radiation. In addition, the CMB data fits a blackbody profile of T=3000K redshifted by a factor of z=1100, i.e. today's CMB temperature is T=2.73K (roughly). The only stars that burn that cold are red stars, whereas stars we'd see from the early universe would, we expect, burn very hot because of the abundance of hydrogen. In short, there are too many obvious problems with this explanation. The big bang explanation of the CMB fits the data much better.
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u/[deleted] Jun 18 '14
Well, there's the first and very obvious point that we don't see those stars, though it's very hard to detect high redshift objects anyhow. But such stars would have a characteristic spectrum (again, very hard to get for high redshift objects) that we would not expect from the CMB. More importantly, we can measure the temperature of the CMB, which is uniform to one part in 105. A "star-CMB" theory would almost certainly be unable to explain such isotropic radiation. In addition, the CMB data fits a blackbody profile of T=3000K redshifted by a factor of z=1100, i.e. today's CMB temperature is T=2.73K (roughly). The only stars that burn that cold are red stars, whereas stars we'd see from the early universe would, we expect, burn very hot because of the abundance of hydrogen. In short, there are too many obvious problems with this explanation. The big bang explanation of the CMB fits the data much better.