Cosmology and Dark Matter

I'm looking for an opinion on two cosmological concepts I've had from reading the popular literature.First: Could the Big Bang have been a vacuum fluctuation/pair production with our matter universe one of the pair, and the other universe of the pair traveling backwards in time and containing all the antimatter. Could this be a way to explain the absence of antimatter in our universe? Second: recent studies have suggested that dark matter may react with itself in a manner other than gravity.IF matter attracts matter with the strength constant G, and dark matter attracts matter with a strength constant A, and dark matter REPELS dark matter with a strength constant B; could the observed effects of dark matter and dark energy be accounted for with a proper ratio of G to A to B?? I assume A>B since dark matter appears to clump with matter. I don't have the data or the math to suggest their magnitudes relative to G, but I'd be surprised if A=G.
- Ronald Swager (age 64)
glenarm, IL USA

I don't know how to answer your first question except to say that that isn't the usual view. I hear that the matter/antimatter disequilibrium only sets in at a temperature scale below that of the early post-Bang era. So it wouldn't be a direct remnant of the BB itself.

On the second question, there are some things to clear up. Most importantly, the universality of the gravitational interaction between all things, including dark matter, is built very deeply into the whole well-confirmed structure general relativity. So the types of dark matter interactions that are being explored are not alternatives to gravity, but additional effects, just as the electroweak force and the QCD force are for familiar matter.

Presumably, your question is motivated by the new results on possible dark matter self-interactions:  . Even if there are new interactions they are not guaranteed to be long range, unlike gravity. Most forces are in effect short-range because objects on even a pretty small scale are neutral with regard to the sources. For example, most objects are very nearly electrically neutral because they combine positive and negative charges. Likewise all ordinary matter consists of color singlets, meaning it's QCD neutral. Gravity is the exception to this behavior because all objects attract gravitationally so there's no antigravity stuff to make a net gravity neutral thing. That means that it's pretty much impossible to mimic the large-scale effects of gravity via some other force.
Ordinary interactions suffice to exchange momentum between ordinary matter objects and similar ones would also suffice to allow dark matter objects to exchange momentum. At present (6/15) the evidence for such interactions in dark matter is very sketchy.

Mike W.

(published on 06/24/2015)