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Q & A: uniform accelerating expansion of space/

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Most recent answer: 11/06/2015
Q:
Is the expansion of the universe uniform, that is - is the distance to any two equal 'far away' object increasing with the same accelleration? that is - if two objects right now is like a billion lightyears from earth (in different directions) will they then in a billion years both be c*billion years away from earth (where c is some arbitrary constant)? If not then my next question is - what is the reason? - if we beleave in dark energy does that mean that it is not uniformly distributed? and what can be observed about the areas where the expansion is 'biggest'? - is it perhaps areas with 'dence presence' of matter (dark or visible), or is it in areas with lack of matter, or does matter not matter? (not to be considered as a joke).
- Flemming Bo Hansen (age 51)
Denmark
A:

All indications are that the dark energy or cosmological constant or whatever is driving the acceleration of the expansion is uniform in space, and also has been constant or nearly so over a long period of time. The other stuff  (our type of matter and dark matter) is not uniformly spaced, as you can see at night. So that leads to a little bit of unevenness in the acceleration, since those types of matter cause deceleration.  On a large scale, however, even matter seems uniform, so the acceleration is nearly uniform.

Mike W.


(published on 11/06/2015)

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