New Map of Universe Casts Doubt on Basic Theories

A new map of the universe appears to confirm the growing suspicion among astronomers that current theories about how the universe was formed are deeply flawed.

The new map of the cosmos, compiled from observations of a sophisticated orbiting satellite and published Thursday in the British journal Nature, indicates that the heavens contain far greater numbers of massively large objects than can be accounted for by conventional theories.

The new results do not overturn the so-called “Big Bang” theory of the formation of the universe, which suggests that the universe started in a massive explosion. But they do call into question cosmologists’ speculations about the nature of matter in the vast reaches of space between galaxies, which formed in that cataclysmic event.

Cosmologists have argued for five to 10 years that more than 90% of the matter in the universe is so-called “cold dark matter,” invisible to astronomers on Earth. The existence of this cold dark matter has been crucial to explanations of how individual stars and galaxies formed.

But the group of nine British and Canadian researchers who compiled the Nature paper say unequivocally that the cold dark matter theory must be abandoned.

The new results and their interpretation are “sensational,” in the words of Nature editors, because they come from astronomers who have been among the strongest proponents of the cold dark matter theory.

Caltech cosmologist S. George Djorgovski noted that the number of astronomical observations that contradict the cold dark matter theory has been increasing for several years and the demise of the theory seemed inevitable. “The writing has been on the wall for a long time,” he said.

Others, however, argued that the new results may provide the final blow to the theory. The new results, said astrophysicist Jeremiah P. Ostriker of Princeton University, “sound the death knell” for cold dark matter.

The crux of the problem is that the motions of galaxies, quasars and other objects through the universe cannot be explained by the gravitational effects of those objects that can be seen through telescopes. In fact, those visible objects provide only about 10% or less of the gravitational effect necessary to explain celestial motions.

Scientists thus believe that there exist large amounts of “dark” matter that is invisible, but that nonetheless exerts a strong gravitational influence. However, the precise nature of this material has been unknown.

The cold dark matter theory postulates that this unseen material is composed of conventional atomic particles and atoms that are moving so slowly that they would not radiate any detectable energy. Since the Big Bang, some of these particles have been drawn together by their gravitational attraction, forming all of the visible objects of the universe, while the remaining particles make up the “dark matter,” according to the theory.

But in recent years, astronomers have observed still larger structures in the cosmos, such as the extremely long sheet of galaxies called the “great wall” and a very powerful concentration of gravitational pull called the “great attracter.”

The cold dark matter theory could accommodate--albeit uncomfortably--one or two such aberrations. But the new surveys of the sky conducted by the orbiting Infra-Red Astronomical Satellite since the mid-1980s indicate that such large objects are relatively common throughout the universe.

The 15-billion- to 20-billion-year lifetime of the universe now accepted by scientists is not nearly long enough to allow for the formation of such large objects through the mechanisms explicit in the cold dark matter theory. At least 100 billion years would have been required.

Hence, the dark matter must be made of something other than conventional particles. But no one is quite sure what that something is. One hypothesis is that it is composed of neutrinos, atomic particles that are believed to have virtually no mass and that are invisible to most types of observation. The new results would require the existence of a neutrino with appreciable mass--a particle that has never been observed.

So cosmologists are going back to the drawing board, dusting off old theories and putting together adaptations of existing theories. But the situation is not a crisis, Djorgovski said.

“Progress in science is made by rejecting theories, not by supporting them,” he said. “This is just one of those minutes when people have to sit down and think a little harder.”