| The way I understand it, dark matter is a term used to explain the missing mass of the universe. We know that the universe is expanding at a certain rate, but that rate of expansion does not coincide with what it should be according to how much mass is out there. Therefore there must be mass out there that we do not see, or know of.
In 1998 it was show that neutrinos, that were previously thought to have no mass at all, do in fact have mass, it is extremely low, but it's there. When you take into account the billions of billions of billions of neutrinos out there, that explains a nice chunk of the missing mass.
Rather than dark matter, physicists now wonder about a newly discovered phenomenon: dark energy. Given our understanding of gravity, the universe should be expanding at a constant rate, or, depending on the mass of the universe itself, galaxies should be slowing down the farther away they get from the center of the universe. What is being observed though, is that the galaxies are actually moving away faster as they get further. The only way of accounting for that is that something is pushing them away.
So dark matter, doesn't actually exist in a textual way. There may or may not be things out there that we cannot perceive yet. But they are certainly not nothing.  |