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drhex
2008-Nov-21, 07:31 PM
I've just finished "Death from the skies", and it refers to another interesting book, "The five ages of the universe" (Adams/Laughlin) when discussing the fate of the universe in the far future.
The five ages (written 1999) mentions three sources of energy when fusion no longer works: dark matter annihilation, proton decay and Hawking radiation. Death from the skies mentions the latter two, but not the first.
At page 91-94 of The five ages, it is described how dark matter annihilation is supposed to work: the WIMPs that DM consists of slowly gravitate towards the center of white dwarfs where they find other DM particles to annihilate with, letting the star remnant produce 10^15 Watts (to compare to the 10^26 Watts it produced with fusion).
Given that we do not know today what kind of particles make up DM, and certainly didn't know more back in 1999, is the scenario from The five ages out of fashion now?

formulaterp
2008-Nov-21, 09:57 PM
Recent studies of cosmic rays may indicate dark matter annihilation is occurring:

From the BA Blog: http://blogs.discovermagazine.com/badastronomy/2008/11/19/something-powerful-lurks-nearby/

Still seems quite speculative, but then again, finding energy sources 50 billion years from now sort of requires a bit of imagination.

drhex
2008-Nov-23, 09:29 PM
Thanks for the link.
I think we are talking about 100000000000000 billion years into the future until DM annihilation will be a significant player in the field of power sources.

mugaliens
2008-Nov-23, 11:43 PM
Have you considered designing a pair of sub-atomic scale grids, one of which captures positively charged virtual particles and the other captures negative particles. Neutral particles would be ignored.

Just be sure you detune the sucker so that it only captures one in several trillion trillion. Otherwise you won't be lighting up New York City. You'll be lighting up half the planet, but in a bad way.

Vallkynn
2008-Nov-24, 01:37 PM
The five ages (written 1999) mentions three sources of energy when fusion no longer works: dark matter annihilation, proton decay and Hawking radiation. Death from the skies mentions the latter two, but not the first.

Why do you think fusion will no longer work? Lack of fuel?

I don't think that universe will fall into a thermal ash, I believe it's either cyclic, or there's some balance between at least two dimensions, otherwise we would have been in a thermal ash for long.

trinitree88
2008-Nov-24, 06:56 PM
Why do you think fusion will no longer work? Lack of fuel?

I don't think that universe will fall into a thermal ash, I believe it's either cyclic, or there's some balance between at least two dimensions, otherwise we would have been in a thermal ash for long.

Vallkyn. Fusion will only produce energy as long as you have light nuclei...less than nickel and iron, as per the curve of binding energy. Fission works for the heavier ones. Nothing works in the middle.

see:http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html


see:http://csep10.phys.utk.edu/astr162/lect/energy/bindingE.html

LotusExcelle
2008-Nov-24, 06:57 PM
Marshmallows. I've said enough.