Ten Thousand Billion Years to Go

To a cosmic eye this particular universe --the Milky Way--is a wispy thing, a puff of tiny particles which are billions of stars. Somewhat disk-shaped, it floats in space, spinning on its shorter axis. The sun is one of these stars, located some four-fifths of the way out from center of the universe toward the edge. At that point its spinning motion is 155 miles per second, yet it takes 200 million years to round the circuit. Ten times the earth has been around, clinging to the sun, from which, scientists believe, the earth spun off two billion years ago.

How long will this go on? Ten thousand billion years more, says the University of Chicago's astrophysicist, Subrahmanyan Chandrasekhar, whose book, Principles of Stellar Dynamics, has just been published (University of Chicago Press; $5). Beginning with a compact, enormously dense mass of some eight billion degrees Centigrade (TIME, June 1), the Milky Way galaxy has been expanding for three billion years, will continue to expand for at least 9,997 billion more. By then it should be completely relaxed, the stars will all have the same velocity, and will begin to slip away from the galaxy like molecules of water evaporating from a puff of steam. At this point Astrophysicist Chandrasekhar's imagination, like that of most scientists, also relaxes.

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