The Dark Side of the Universe

For physics professor James Trefil, the new cosmology removes the visible universe from pride of place in cosmic theory; visible matter may be mere decoration on the immense superstructure of dark matter that constitutes perhaps 90 percent of the cosmos.

The Big Bang--the moment of creation--is often simplistically pictured as a massive explosion that led, some ten or twenty billion years later, to the present universe. Modern theory suggests that space itself began to expand in the Big Bang, and that within the first three minutes the material nature of the universe, with its strong and weak forces (such as electromagnetism and gravity), was essentially determined. Atoms began to form a mere hundred thousand years later. In their attempt to work out the complexities of the Big Bang, cosmologists ran into the most vexing problem of all: how to account for the formation of galaxies and the strings of galaxies called superclusters. There did not seem to be enough visible matter in the universe, and thus not enough gravity, to overcome the outward force of the expansion of space. Thus no clumps of matter could have formed by gravitational attraction to condense into galaxies. If, however, enough dark matter--substance which cannot be observed, that radiates no energy but that does exert gravitational force--is postulated, the objection is overcome.

Trefil speculates on the existence of two kinds of dark matter: one, a neutrino with mass (as yet undiscovered), could account for the condensation of visible matter into galaxies; another, so-called cosmic strings (vast, snakelike multidimensional lines), might explain the galactic supercluster configuration.

Trefil’s account of the search in the latter 1980’s for a mathematically elegant Theory of Everything (perhaps involving dark matter) is breezy and anecdotal. Aside from his tendency to moralize about human self-centeredness and the glories of science, the trip to the dark side of the universe is most illuminating.