Science: Now, the Death Ray?

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Like so many other triumphs of science, the laser has become a double-edged sword. Capable of producing an enormously powerful, very narrow beam of light, it has been used to perform delicate surgery on the retina of the eye, puncture tiny holes in material as hard as diamonds, produce three-dimensional pictures called holograms, and even measure the distance from earth to the moon (with an error of only a few inches). But the laser can also be used for less peaceful purposes. It provides, for example, the guiding light for the Air Force's extremely accurate "smart bombs" (TIME, June 5). Even more ominous, the laser may be on its way toward becoming a military weapon that until now has existed only in fiction: the death ray.

Much of the Pentagon's laser weaponry research is conducted in great secrecy at Kirtland Air Force Base, outside of Albuquerque, at a desert site not far from Los Alamos, the birthplace of the atomic bomb. To some experts, the project (code-named "Eighth Card") is almost as important as the Manhattan Project three decades ago. It is not for security reasons alone that frequent warnings are issued to commercial and private planes to keep away from Kirtland; laser beams fired at the base's new weaponry range are known to have ignited wooden targets at a distance of at least a mile. Some reports claim that beams have knocked down remote-controlled drones flying overhead. Even if one of Kirtland's lasers did not damage an intruding aircraft, it could blind any pilot or passenger who looked directly into it.

What may well be the most important goal of military researchers at Kirtland and elsewhere is to project a laser beam that could intercept and destroy a fast-moving intercontinental ballistic missile when it is most vulnerable—before the booster separates from the warhead. Long a subject of fanciful speculation, such long-range rays may soon become possible because of recent technological breakthroughs like high-energy gas dynamic lasers, which produce beams of laser light when their internal gases are rapidly heated, expanded and forced through tiny nozzles at supersonic speeds. Some new lasers have given off bursts of power equivalent to billions of watts, enough to light briefly all the lamps in a major city.

The new generation of lasers shows so much military promise that the Pentagon will spend some $90 million this fiscal year on "electro-optical warfare," nearly double the figure of two years ago. The Russians, also interested in laser weaponry, are thought to be spending even more, and may well be ahead of the U.S. research effort. Only a few months ago, Soviet scientists announced that they had generated a pulsed laser beam of 300 billion watts.*

Proverbial Arrow. The very nature of laser light gives it a potential for destruction. Unlike ordinary light, which consists of a chaotic jumble of electromagnetic waves of different frequencies, laser beams are composed of light waves of only a single frequency. These waves are not only parallel but are also in phase: their crests and troughs coincide and reinforce each other, making it possible to produce an extremely intense and concentrated beam. In practice, however, lasers have drawbacks. The beams collide with molecules in the atmosphere and weaken over long distances; like sunlight, they may be blocked by clouds.