Dark Matter and the Origin of the Universe
Most recent answer: 11/27/2013
- Michael Polidori (age 60?)
Newport News Va
That's a lot of questions! I'll answer some to get you started.
It's unlikely that dark matter (assuming that's the right interpretation of the data) played a key role in the origin of the universe. Dark matter clumps up with the more familiar matter, inside our universe. That's pretty much the opposite of thinking of the universe as floating in some sea of dark matter.
Perhaps what you have in mind is something close to the "eternal inflation" (good search term) picture. There some form of dark energy, in some ways similar to the stuff driving the acceleration of our current expansion, drives an accelerating expansion which sheds countless universes like ours. That's pretty much a standard picture, at least for the time being. There are arguments that even in such a picture there would have to be a singularity at the start, if one ignores quantum gravity. However, the general consensus is that a theory of quantum gravity will replace the singularity with something or other. Some sort of ongoing re-creation cycles are one possibility, discussed in Sean Carroll's From Eternity to Here.
The picture of there being a set of ultimate "elementary particles" may not be right. The stuff that comes out of a high energy collision is not necessarily any more or less fundamental than what went in.
Mike W.
(published on 11/27/2013)
Follow-Up #1: alternatives to dark energy?
- Michael Polidori (age 60?)
Virginia, USA
If I understand you correctly, your idea is a rather old one- that a special distribution of ordinary mass could have effects that mimic the universal acceleration predicted for dark energy. Recent tests of this idea have shown that it doesn't work: . If I understand the argument correctly, there's not enough density of ordinary attractive mass (including dark matter) to provide for a big enough spatial variation to mimic the whole apparent acceleration.
The dark energy hypotheses doesn't just come out of nowhere. One typical result as things cool down is that they get stuck temporarily in supercooled states with higher energy than the true equilibrium state. Without any further fudging, the general relativistic equations predict that should cause accelerating expansion, i.e. inflation. There's lot's of evidence that such an effect happened very intensely very early in the history of the universe. And there's lots of evidence that it's been happening weakly for the last few billion years.
Alternate theories are still welcome, and may win in the end. The key thing is to find ways of testing them.
Mike W.
(published on 04/06/2014)