Although for at least 10 years, since the WMAP satellite first measured the amounts of dark matter in the universe, scientists have known the recipe for the universe (4.5% Matter,22.5% Dark Matter, 73% Dark Energy) but really didn't have a clue as to what the Dark Matter and Energy of the universe actually is. One theory of dark matter is a WIMP, a weakly interacting massive particle left over from the big bang, is the lightest super-symmetric particle, LSP. That theory fit in well with the prevailing super-string and super-symmetry theories of particle physics, and the numbers actually worked out when physicists tried predicating how much dark matter the big bang might make. But recently three separate observations in astronomy seem to have ruled this model out.

If 2011's strangest result was seeing neutrinos moving in excess of the velocity of light, how could 2012 top that. But an even stranger experimental result has come from Berezhiani and Nesti from the University of Aquila in Italy , who claim to have found neutrons oscillate into Mirror Neutrons, and thus disappear from the ultra cold neutron traps. Mirror Matter is a theory of dark matter, in which every particle from the standard model is has Mirror Matter copy with left and right reversed, in order to return to parity conservation. Matter Matter has is own copy of each of the standard model strong and electroweak forces, and Mirror Matter interacts only with its own copies of the forces.

I read ArXiv regularly. It's not easy because most of the latest publications of physics go there before print. Apart from pedagogical articles (for teaching purposes), all the articles are aimed at other scientists working at the state of art in the subject. I try read the principles at the beginnings of the paper, skim the maths, and see if the conclusion match the rest of physics. So apologies to the authors if I accidentally misquote them.

Today there were enough fascinating articles that I wanted to write about them. This might become an occasional series so let me know if you find this useful.

I was going to talk about neutrinos today, as the results of MiniBoone looking at how muon neutrinos mix into electron neutrinos had just been published earlier this week, and wanted to write about CP violation and a possible 1-2eV right handed neutrino mixing or decaying with/into the left handed neutrinos that the weak nuclear can turn electrons into. However, I think for most readers the faster than light results from CERN in September would be more interesting. 

  Following on my last article, I'd like to ask the question, weither some day, dark matter might be useful or even vital to a civilisation. 
This depends on the properties of the stuff, which of course we haven't found yet. But it seems the standard lightest super-symmetric particle dark matter, most likely wouldn't be much use even to an highly advanced inter stellar civilisation. The lightest super-symmetric particle doesn't do much, it interacts by gravity, and by the weak nuclear force only and sometimes it annihilate with other particles like itself. 

  Over in print media today, New Scientist's cover article was on a "new" idea for what dark matter is. Apparently, dark matter should be composed of Dark Atoms, in a theory introduced by Christopher Wells, et al. In fact, astronomers and particle physicists have been studying many ideas of what dark matter could be for quite a while. Occasionally a summary of the current ideas gets published, such a the 2004 classic, by Silk, even then half the current ideas get left out, such as CHAMP, mirror matter, Q-balls, super weak dark matter and many others.