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Physics, Astronomy & Cosmology / Can higher density of the Universe be responsible for increasing expansion rate?
« on: 09/03/2016 22:10:55 »
Because the Universe is expanding, its average density (on a really, really macroscopic scale) should be reducing. So let's look in any direction from the Milky Way, towards the cosmic microwave background. A galaxy 1 billion l.y. away would be X million years in the past (not 1 billion years, because of the expansion of the Universe). In the past, the Universe was denser than now. Another galaxy 2 billion l.y. away is Y million years in the past (Y>X, but not Y=2X,).
As I understand it, the current consensus explains the fact that the light from galaxy 2 is more (and not proportionately to the distance) redshifted than that of galaxy 1, by saying that the rate of the Universe's expansion is increasing - the further away a galaxy is from us, the faster it is speeding away and the more redshifted its light is.
Is it possible that this disproportionate (to the distance) increase in redshift is actually caused by higher Universe density in the past? Similarly to how the light from a source in a low orbit around a black hole would be redshifted, because the light has to expend energy to get higher gravitational potential or, to put it in another way, the light has to lose frequency when moving from more curved spacetime (closer to the black hole/further back in time when Universe density was higher) to less curved spacetime (further away from the black hole/closer to our time when Universe density is lower).
As I understand it, the current consensus explains the fact that the light from galaxy 2 is more (and not proportionately to the distance) redshifted than that of galaxy 1, by saying that the rate of the Universe's expansion is increasing - the further away a galaxy is from us, the faster it is speeding away and the more redshifted its light is.
Is it possible that this disproportionate (to the distance) increase in redshift is actually caused by higher Universe density in the past? Similarly to how the light from a source in a low orbit around a black hole would be redshifted, because the light has to expend energy to get higher gravitational potential or, to put it in another way, the light has to lose frequency when moving from more curved spacetime (closer to the black hole/further back in time when Universe density was higher) to less curved spacetime (further away from the black hole/closer to our time when Universe density is lower).