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Q & A: alternative to dark energy?

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Most recent answer: 07/17/2013
Q:
Is it possible that the reason for galaxies accelerating away (dark energy) is actually a very weak, repulsive force that all massive objects have, and it is proportional to their mass. If this force were to be incredibly weak but acts over large distances, as they become further apart, the opposing force of gravity becomes less apparent ( therefore giving the reason for acceleration). This force would be so weak that it would be generally undetectable under close ranges. Thanks very much for your help on this. Oliver Freeman (physics student)
- Oliver Freeman (age 18)
Manchester
A:

This is a nice idea but I don't think it will work.  The pattern of the red shifts of the distant "standard candles" not only gives a value for the recent acceleration of the expansion rate but also for the past values.  If you look up references on this the pattern is summarized in a parameter called "w". The value for the parameter is known roughly (~ -1) , and it fits a picture in which the dark energy density is constant. That means that a few billion yers ago the expansion was slowing because the regular matter (including dark matter) was enough denser than now for ordinary gravitational attraction to be stronger than the constant repulsion from dark energy.

What about your idea? The problem is that it relies on a type of force between bits of regular matter, so it would also have been stronger in the past, denser, universe. Even if its strength didn't decrease at all with distance, it would give a w value outside the current error bars.

There may be other problems that would be clearer to people who understand quantum field theory than to me.

Mike W.


(published on 07/17/2013)

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