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After watching Lawrence Krauss' lecture 'life, universe, and nothing', an interesting idea lighted up in my mind. Is it possible that dark matter is just spread out matter waves and dark energy extremely long wavelength light?

matter -> expansion -> dark matter (delocalized matter waves/huge atoms) visible and xray radiation -> expansion -> invisible light with wavelength greater than the diameter of universe (perhaps the source of energy of the empty space?!!!!)

so dark matter today may be what we will become in the future. and we are what dark matter was in the past. eternal expansion just spreads out everything but new stuff is created all the time. anyone living in such a universe at any point of time will see the universe almost as we see it today, expanding with a beginning.

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closed as not a real question by akhmeteli, user1504, Brandon Enright, Waffle's Crazy Peanut, David Z Jun 12 '13 at 15:13

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You appear to be making grandiose speculations based on watching a television program. –  Ben Crowell Aug 5 '11 at 2:28
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""an interesting idea lighted up in my mind."" Does this happen often (resulting in "ideas" like this)? –  Georg Aug 5 '11 at 9:06
    
How do you explain the fact that dark matter interacts through gravity only.? And how do you put any math in your "idea"?. -1/. –  Dimensio1n0 Jul 4 '13 at 4:17

2 Answers 2

This cannot explain dark energy, even in principle, for the following reason. If dark energy were any kind of "invisible light" (that is, electromagnetic radiation of very large wavelength), its pressure and energy density would be related in the standard way for radiation: $p=1/3 \rho c^2$, where $p$ is pressure, $\rho$ is energy density, and $c$ is the speed of light. In other words, in units where $c=1$, the equation of state of radiation is $w=p/\rho=1/3$. There is no wiggle room here; this has been known for more than 100 years and is a result taught in undergraduate physics courses.

On the other hand, the effect of dark energy is to 'push things apart'. Equivalently, its pressure is very negative. In fact, its equation of state has been measured to be $w\approx -1$, with only small error bars (of order 0.1).

So dark energy definitely cannot be explained by any kind of radiation (which has $w=1/3$), matter (which has $w=0$), matter waves, invisible light, etc etc.

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extremely long wavelength light would be measurable as essentially constant (in time and space) electric and magnetic fields. We do not see such thing

I don't know what a 'expanded' atom would look like. If its an atom with a different $\hbar$ then we neither have seen one of those

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By expanded atom, I was referring to matter waves that are stretched out. I think they do experiments in condensed matter physics to produce such delocalized matter. Sorry, I'm a developer, not a physicist. for the first part, what if the wavelength of light is stretched longer than the radius of universe. would it account for dark energy? –  ibe Aug 4 '11 at 21:10

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