dipper@utastro.UUCP (Debbie Byrd) (02/22/86)
Some astronomers have a new model that describes the early universe. More about it -- after this. February 22 Cold Dark Matter The Big Bang theory says that the universe began in a huge explosion. But that theory has left astronomers with a big question. Where is the missing mass -- perhaps as much as 90 per cent of the mass of the universe -- which astronomers believe exists -- yet haven't been able to find? There are many ways to look for the missing mass. One way is to make a model of the entire universe. In one current model, the missing mass consists of cold dark matter -- exotic particles unlike anything we know. These particles are colder than the rest of the universe. They emit no light or other kind of radiation that we can detect. Computations have shown that the galaxies as we know them could indeed have evolved under conditions described by the model. According to this new model of the universe, the Big Bang produced 90 per cent cold dark matter, and l0 per cent ordinary matter. As the cold dark matter expanded outward, dense pockets trapped the ordinary matter and eventually formed shining galaxies -- which were left surrounded by a huge halo of the invisible mass. The model is exciting because it can supply answers to questions that have always been very puzzling. It seems to explain why galaxies rotate and what holds groups of galaxies together. It also fits in nicely with the closed universe theory in which the universe expands and collapses on itself in a cycle that repeats forever. If the cold dark matter is really out there, then it's possible that enough gravity exists to reverse the direction of our expanding universe. Script by Holly Clark. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin