Dark Matter is postulated to explain the motion of galaxies. You see they are not behaving as we expect given the laws of physics as we know 'em (and which work very well indeed) with the input into those laws being the galactic mass distributions that we can see. To make it all work i.e., to make the observations align with the theory, we need more mass. Lots O' mass. Hence the generally accepted theory that there must be mucho mass out there (and passing through us) that we simply can't see because, well, it's dark.
It's dark, but nothing is invisible. Dark means it doesn't easily interact with other matter, and so it is hard to detect. So theorists postulate a number of candidates for dark matter that interact very weakly--and then build detectors that are extremely sensitive.
The detectors, so far, are seeing nothing. Many believe that we should have seen something by now. Dark matter is either darker than expected or it is not there. If it is not there our theories are in need of a serious overhaul.
Here is the latest dim report, from Nature.
Physicists are growing ever more frustrated in their hunt for dark matter — the massive but hard-to-detect substance that is thought to comprise 85% of the material Universe. Teams working with the world’s most sensitive dark-matter detectors report that they have failed to find the particles, and that the ongoing drought has challenged theorists’ prevailing views.Bummer. Or is it? I'm not sure what would be more interesting: finding Dark Matter or realizing that we don't know as much as we think we know.
That's why science rocks.
Dark Matter and Dark Energy are are unknown in human knowledge that some people assume a priori (materialists) that they are materials.
ReplyDeleteDark Matter what is and what does is unknown anything else are assumptions and should be treated as a hole in scientific knowledge (a gap).