Catastrophic Beginning

The most ambitious job that astrono-- mers attempt is trying to figure out how the universe was formed. Two hypotheses dominate their debates. The "continuous creation theory" (TIME, Nov. 20, 1950) holds that the universe had no beginning and will have no end. It changes locally somewhat because of the "creation" of new matter (hydrogen atoms) in space. The hydrogen draws together to form new stars and galaxies, which gradually drift apart. But except for such "details," the universe is always in a "steady state." One thousand billion years from now it will be pretty much in the same condition as it is today.

The opposing, "catastrophic" theory holds that the universe was formed by a vast explosion that gave it the rough outlines of its present structure. Since the great blowup, the universe has been expanding, but other changes in it have been "local."

In the Scientific Monthly, Dutch-born Astronomer D. Ter Haar of the University of St. Andrews, Scotland, gives a roundup of evidence in support of the catastrophic theory. Ter Haar reasons that if the universe was formed at a single time, many objects in it should have roughly the same age. Then he gathers a collection of age estimates to see how closely they agree.

Comparative Ages. The age of the earth can be estimated in several ways. It loses heat to space, but it also gains heat from the decay of radioactive materials. By balancing the estimated losses against the gains, scientists have concluded that the earth's crust needed two to four billion years to reach its present temperature. The age of the crust can also be estimated by measuring the products of radioactive decay that are found in its oldest rocks. This figure comes out to about three billion years.

Since most astronomers agree that the earth and the moon became partners when the solar system was formed, the age of the earth-moon combination is also the age of the solar system. Because of the drag of the tides, the moon is slowly moving away from the earth. The best estimate, says Ter Haar, is that it took the moon two to four billion years to reach its present distance. This gives the age of the earth-moon partnership, and therefore the age of the solar system: two to four billion years.

Clustering Stars. Estimating the age of the stars and the Milky Way galaxy is a much more complicated business, but astronomers have tackled it too. One figure, based on the amount of helium that the sun has made out of its original hydrogen by a nuclear reaction, gives the sun the age of five billion years. Another, based on the clustering of stars in the galaxy, makes the galaxy itself two to five billion years old.

All of Ter Haar's figures point to a kind of "beginning" not more than five billion years ago. They afford, he says, "one of the strongest arguments against the hypothesis of continuous creation . . ."

What existed before the "beginning" when the universe exploded? Ter Haar is careful not to answer this biggest question of all. He says merely that "the present epoch" started with the great blowup. What went before he does not claim to know.

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