Power from Gravity

Scientists have suggested any number of exotic solutions to the energy crisis --from harnessing ocean currents to using the earth's magnetic field. Now researchers at the Atomic Energy Commission's Lawrence Livermore Laboratory have conceived perhaps the most imaginative scheme of all. They propose tapping what might well be the ultimate energy source: a "black hole"--a small celestial object that is trillions of times denser than ordinary matter.

Predicted by relativity theory and apparently recently detected in space (TIME, Dec. 10), a black hole is formed during the death throes of a giant star.

As the nuclear fires go out, the stellar gases begin falling inward, finally crushing together into a ball less than three miles in diameter. Tiny as it is, the dense globe has such tremendous gravity that not even light can escape from it. Its gravitational force is so great, in fact, that a black hole could swallow up a nearby planet or even a small star.

In 1971 a young British theorist, Stephen Hawking, speculated that mini-black holes may also exist. According to his theory, during the first chaotic moments of the Big Bang (the great explosion that is believed to have created the universe 10 to 15 billion years ago), some pockets of matter may have been forced to contract rather than expand.

They could have crushed together into tiny black holes--some of them even smaller than a virus. These black holes would have relatively strong gravitational fields, but observers could approach within several hundred feet without being drawn into them. According to AEC Astrophysicists Lowell Wood, Thomas Weaver and John Nuckolls, if such bizarre little objects do indeed exist near the earth, their gravity might well be put to work.

Hungry Pet. For starters, the scientists recently told the New York Academy of Sciences, one of the black holes would have to be located. For example, a small, unaccountable gravitational tug on a spacecraft might be a good indication that one was near by.

The ship could take it in tow by simply feeding it matter: like a hungry pet following its master, the black hole would be tugged along by mutual gravitational attraction as it gulped the material.

Once the black hole was positioned in a permanent orbit around the earth, its gravity could be tapped. From a distance of 100 yds. or so--far enough away to avoid being drawn into the black hole --an automatic firing mechanism on a spacecraft orbiting near by would aim tiny pellets of matter at it. Almost any material would do. As each pellet plunged toward the black hole, it would be squeezed and heated by the gravitational field to tremendously high temperatures, perhaps 100 million degrees.

That would be hot enough to start fusion, the same energy-releasing reaction that fires the sun or an H-bomb. Some of the material would be consumed by the black hole, but most of it would be explosively blown away as extremely hot electrified gases. By letting these gases pass through a magnetic field created by a generator aboard the spacecraft, a powerful electric current could be induced in wires rigged outside the craft.

To get the energy to earth, the current would be converted into microwaves, which would be beamed at huge ground-based antennas and then transformed into ordinary household current.

Science fiction? Wood and his colleagues concede that scientists may never be able to find--or tame--mini-black holes. But they feel that the potential payoff surely justifies the attempt.

Harnessed high above the earth, where it would produce no thermal, chemical or radioactive pollution, a single mini-black hole could fulfill all of mankind's power needs for the foreseeable future.

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