Science: The Sound of Security

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Deerfield, in western Massachusetts, is a quiet New England village undisturbed since the raids of the French and Indian War. Its elm-sheltered main street is lined with early American houses; at least one resident still drives a horse and gig. But Deerfield is not so serene as it looks: at all too brief intervals, a thunderous boom splits the air, several hundred ancient windows rattle in their frames, and sometimes one breaks.

Like hundreds of other U.S. towns, Deerfield has become an unwilling part of a supersonic age. Jets from Westover Air Force Base, 25 miles to the south, blur past overhead—and lower the sonic boom on peaceful Deerfield. "Why can't they go out over the ocean if they want to break the sound barrier?" asks a local schoolteacher. His complaint is as familiar on the West Coast as on the East. And in the last three years, more than 1,000 civilian damage claims, seeking more than $500,000, have been filed against the U.S.

Actually, the breaking of the sound barrier is nothing more than the point at which the noise is turned on. Air is a fluid, and, above the speed of sound (about 760 m.p.h.), it reacts much like the surface of a lake when a speedboat rips across it: waves go out and roll toward land. The sonic boom occurs when the shock wave from a jet hits the nearby ground. It follows the plane wherever it goes, and the pressure may make a sound equal to ten thunderclaps.

The sonic boom was never so explosive as it was last August, when a U.S.A.F. fighter pilot demonstrated his Lockheed F-104 Starfighter to Canadian officials at Ottawa's Uplands Airport. It was a trial run. Next day the pilot was to put on a show at the dedication of the airport's new terminal building, a great, shiny green-glass cavern with an aluminum and stainless-steel structure. Answering an official's request to see him buzz the field, the pilot swung the Starfighter out in an arc, then leveled and came in low and flat. Like a bullet, he was gone. And—boom—so was the new terminal. Only splinters were left of more than $10,000 worth of glass; the whole north wall was smashed; tiles fell from the ceiling, and insulating material poured to the floor. Door frames, window frames, and even structural beams were twisted. Damage: $500,000.

To Air Force public relations men, the sonic boom is a splitting headache, without apparent remedy. "We must learn to live with it," said one recent Air Force release, "for in today's unsettled world we cannot live without it. The boom is unavoidable. It is the sound of security." Even the residents of Deerfield could agree that the point was sound—but that didn't make them like the boom much better.