Dark energy's affect on light?


by alext180
Tags: affect, dark, energy, light
alext180
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#1
Nov11-12, 06:16 PM
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If dark energy repels things at the speed of light, does that mean if light energy is produced near it, it would repel it so hard and fast that it could actually damage things with a light beam? Basically what I'm asking is does dark energy repel light and if so could the light beams damage things?
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Drakkith
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Nov11-12, 06:22 PM
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Dark energy does nothing of the sort. Dark energy is simply the name of whatever is causing the acceleration of the expansion of the universe. This expansion does not work the way you are imagining it, nor does light.

http://en.wikipedia.org/wiki/Metric_expansion_of_space
http://en.wikipedia.org/wiki/Dark_energy
marcus
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Nov11-12, 09:32 PM
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Quote Quote by alext180 View Post
If dark energy repels things at the speed of light, does that mean if light energy is produced near it, it would repel it so hard and fast that it could actually damage things with a light beam? Basically what I'm asking is does dark energy repel light and if so could the light beams damage things?
It hasn't been shown to actually be an energy, Alex. So the name is a bit misleading. What seems to fit the observations best so far is simply a curvature constant that appears in the GR equation. A very small residual curvature that is inherent in spacetime geometry. Not necessarily resulting from any mysterious "energy". Over the past couple of years some scientists have started preferring to call it "vacuum curvature" instead of "dark energy".

I can tell you the exact curvature if you want to know, it is measured in units of inverse area.
A curvature is the reciprocal of an area ("one over" some area expressed in square kilometers or square lightyears). So a very tiny built in curvature corresponds to a very big area. That is just how the Cosmological Constant happens to be expressed mathematically---it's a constant curvature.

It contributes to expansion and expansion is what stretches wavelengths and redshifts light, but this expansion is very very slight, only 1/140 of one percent every million years. And the inherent curvature has contributed so far only a fraction of that!

Otherwise the Cosmo curvature Constant does not affect light! It is very un-dynamic. Not a big deal. So you would not expect it to deflect light or cause physical effects like that.

I agree in general with what Drakkith said just now.


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