Dark Matter, WIMPS, and NASA's Alpha Magnetic Spectrometer Data 44
cylonlover writes "Recently the media has been saturated with overly-hyped reports that NASA's Alpha Magnetic Spectrometer may have detected dark matter. These claims may have some justification if the word 'may' is shouted, but they rest on a number of really major assumptions and guesses, some of which are on weak and shifting soil. So just what was seen in the experiment, and what are the possible explanations?"
Re:why no dark matter black holes? (Score:5, Insightful)
If dark matter only reacts to gravity, why doesnt collapse into hgh density clumps over the eons? Ordinary matter is stopped from doing this by the electronmagnetic repulsion of atoms for masses less than a few hundred Jupiters and by hadronic stong force for less than couple Suns.
It does, we call those clumps "galaxies".
Note that the virtue of interacting only a little bit with normal stuff (via only the weak and gravitational forces, not gravity alone) actually makes it harder for dark matter to pack in tightly. Why? it's hard for a distribution of dark matter particles to shed kinetic energy and settle down more deeply into the gravitational potential well. Ordinary matter has all sorts of electromagnetic ways to shed energy and cool down.
If this thermal argument is opaque, imagine one WIMP, with some kinetic energy. It falls down towards the center of a galaxy. But, it seldom interacts to lose any energy, so zooms right back out the other side. Sort of a tiny, frictionless pendulum with a galaxy sized amplitude.