Support for the Big Bang

A British scientist reported last week about an event that might seem unreportable: the birth of the universe. Cambridge University Radio Astronomer Martin Ryle performed the feat by taking a look at part of the universe as it existed 8 billion years ago.

Ryle's findings provided new evidence in an old astronomical dispute. Astronomers agree that the universe is made of gigantic star clusters--galaxies--that are racing away from each other like the hot molecules of an exploding gas. But they do not agree why this is happening or how it started. The simplest explanation, the "evolving universe" or "big-bang" theory, is that a few billion years ago, all matter in the universe was concentrated in a relatively small volume of space. Then a vast explosion scattered the cosmic material, which formed into galaxies and fled into emptiness.

The opposing explanation, the "steady-state" theory, holds that matter is being created continuously in the form of hydrogen atoms that appear in space. Little by little, the newborn matter clumps together, forming galaxies that repel each other and move apart. As they grow old and separate, new galaxies form in the widening gaps between them. The steady-state universe has no center or outer boundary. It had no beginning and will have no end.

Colliding Galaxies. Early attempts to decide by observation which kind of universe is the real one were not successful. Optical telescopes, even the 200-in. giant on Mount Palomar, could probe only 2 billion light-years into space. But telescopes using radio waves, which have the same speed as light waves, can see much farther. Certain rare celestial objects, pairs of galaxies in collision, send out enormous quantities of radio waves; they may look very bright to radio telescopes, while optical telescopes can hardly see them at all.

When this fact was discovered about ten years ago, Cambridge's Martin Ryle drew the obvious conclusion that colliding galaxies should be visible to radio telescopes even if they are billions of light-years beyond the maximum range of optical astronomy. So he set to building bigger and more sensitive radio telescopes.

His latest instrument, built in 1958, is an intricate web of wires and spidery, movable arms that covers nearly five acres of ground and can count colliding galaxies that are 8 billion light-years away.

Crowded Space. Last week Ryle reported to the Royal Astronomical Society that after carefully surveying many strips of the sky, he had come to the remarkable conclusion that colliding galaxies get more crowded in space as they get farther away. Those that are 8 billion light-years away occur eleven times as thickly as those near the earth. If pairs of colliding galaxies are closer together at that distance, Ryle reasoned, noncolliding galaxies, which are 100 million times more numerous, must be closer together, too.

This was bad news for the steady-state universe theory, which maintains that all parts of the limitless universe contain about the same number of galaxies for equal volumes of space. It was fresh support for the big-bang theory. Since light takes one year of time to cover one light-year of distance, galaxies 8 billion light-years away from the earth are viewed as they were 8 billion years ago. It is only natural, said Ryle, that they seem more closely packed. Eight billion years ago they were closer to the original bang and had not had time to spread out as thinly as at present.

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