Life Without End

Most astronomers and theologians assume that the earth's life began on the earth. Maybe not, thinks Cornell's Astronomer Thomas Gold. In a paper read at a Los Angeles meeting of space scientists, Gold suggested that "life" may have existed elsewhere in the universe for uncounted billions of years before it took root on the earth. How did life reach the earth and begin its long climb toward human consciousness? His answer: perhaps it was brought by spaceships.

Life has existed on earth for about one billion years. Gold points out. It began as very simple forms of microscopic size, has developed slowly until only now is it reaching a level of physical development and technological competence that will allow descendants of those microbes to travel outside their own solar system. Certainly within the next few hundred years, he holds, man will be visiting planets of other solar systems. "Most of these planets will have unsuitable conditions for us to live there freely, but if they have no life on them, it is still possible that they can be contaminated with some form of microbiology brought along by the space travelers. Low forms of life are adaptable to a great variety of conditions, and so it is likely that they will stay on the planets while the space travelers will not."

After a billion years, in the Gold hypothesis, the seeded planet may have evolved creatures intelligent enough to travel deeper into space, visiting fertile but virgin planets and seeding them in turn with adaptable microbes. In fact, this contamination by life is probably the normal beginning of life on any planet, including the earth. "Space travelers," says Gold, "may have visited the earth a billion years ago, and from their abandoned garbage forms of life have proliferated so that the microbes will soon have another agent (space-traveling humans) capable of spreading them farther afield."

What about the other galaxies that float in space far beyond the limits of the Milky Way? Astronomer Gold is one of the leading proponents of the steady-state universe theory, which holds that as old galaxies move apart, new galaxies form between them out of freshly created matter. Planets in new galaxies, he says, may be lifeless for a while, but eventually the contamination will reach them too. All they need is a single visit from an intergalactic germ-spreading spaceship.

When, then, did life begin? The steady-state theory holds that space has no boundaries, and time has no beginning or end. If life spreads from old to new galaxies with the flow of time, its history may extend backward forever. It may live forever, too, renewing itself at inter vals of many billion years by planting its seeds on planets in galaxies not yet created.

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