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> The amount of visible matter only accounts for 4% of the cosmic microwave background. Could you explain what do you mean by 'accounts for 4% of the cosmic mi
by effie 9y ago
> The amount of visible matter only accounts for 4% of the cosmic microwave background.
Could you explain what do you mean by 'accounts for 4% of the cosmic microwave background'? How is one supposed to account for CMB by matter density, when its spectrum is almost equilibrium one (thus consistent with almost any value of matter density)?
- hwillis 9y agoThe CMB has a certain spectrum and temperature. The amount of energy in the universe correlates to the amount of mass in the universe. The more energy and mass was present in the big bang, the hotter the CMB will be. The amount of visible matter corresponds to a CMB temperature that is far lower than what we see.
- effie 9y ago> The amount of visible matter corresponds to a CMB temperature that is far lower than what we see. Why would there be a relation between CMB temperature and amount of (visible+invisible) matter? I suppose the CMB temperature decreases in time. Would`s the relation you talk about imply that the mass or density of mass of the Universe then has to decrease as well?