An Evolving Universe?

To the big cosmic questions--How did the universe begin? How will it end?--British Cosmologist Fred Hoyle had a pair of startling answers: It had no beginning and will have no end. Instead, according to Hoyle. the universe is a steady state that is infinite in space and time and has a constant density maintained by the creation of new matter to compensate for the thinning of matter by expansion (TIME, Sept. 26).

Writing in Scientific American, two astronomers--Briton Martin Ryle and American Allan R. Sandage--theorize that Hoyle's steady-state universe does not jibe with cosmic fact. Rather, their findings support the rival evolutionary theory that the universe is expanding from its beginnings as a dense state of matter. The evolutionary theory also holds that the universe once expanded at a faster rate than now. Hoyle believes that the universe has always expanded at a constant rate.

Colliding Galaxies. Ryle, a scholar with Hoyle at Cambridge University, bases his theory on recent findings of radio astronomy, the delicate discipline that measures celestial radio signals as faint as a hundred-millionth of the power of a TV signal. Working with signals from 1,936 sources, Ryle notes that 30 come from within the earth's galaxy. He postulates that the remaining, signals come from far beyond the limits of the galaxy and are caused, in fact, by the intermeshing of other galaxies.

Says Ryle: "If most of the radio stars are in fact collisions between galaxies, such encounters apparently are considerably more frequent in distant space (perhaps billions of light-years away) than near us. This disparity would argue against the steady-state hypothesis that the density of matter in space remains constant. The radio signals we are now receiving from distant collisions started on their way billions of years ago. If the evolutionary theory is correct, the universe should have been denser then, and encounters between galaxies more likely."

Speeding Clusters. Using the "redshift" (light from a galaxy speeding away from the earth shifts in proportion to its speed toward the red end of the color spectrum), Sandage studied the speeds of six clusters of galaxies about a billion light-years away. According to Hoyle. the clusters should be moving at a speed in direct proportion to their distance from the earth. But recent calculations show that the clusters are moving about 10,000 kilometers (6,200 miles) per second faster than Hoyle's prediction.

Sandage, assistant astronomer at California's Mount Wilson and Palomar Observatories, notes that this would mean that the universe was expanding more rapidly a billion years ago than it is now. "If the measurements and the interpretation are correct." he says, "this suggests that we live in an evolving rather than in a steady-state universe." Even Hoyle is impressed by these findings, calls them "the most serious potential contradiction of the steady-state theory.''

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