Science: Atom Smasher

When the munitions ship Mont Blanc exploded in the harbor of Halifax, N.S. on Dec. 6, 1917, the shock was felt more than 150 miles away. The explosion killed more than 1,100, laid waste two square miles of the city. The Mont Blanc carried 3,000 tons of TNT. The single atomic bomb which fell on Hiroshima in Japan this week exploded with approximately seven times the force of that tremendous charge.

How the atomic explosive is made is one of the world’s most closely guarded secrets. But the fundamental principle behind it can be understood by any layman.

It was, as President Truman said, a “harnessing of the basic power of the universe.” That power is contained in the atom, the fundamental unit in nature. An infinitesimal universe in itself, the atom consists of a nucleus of protons and neutrons, around which electrons swing in widely spaced orbits, like planets around the sun.

If a drop of water were enlarged to the size of the earth, each atom in it would be about the size of an orange. Yet most of an atom is empty space through which the electrons whirl. The nucleus itself occupies only one million-billionth of the atom’s bulk.

The Target. The atom’s energy, “the basic power of the universe,” is contained in the nucleus. To release that energy, this unimaginably small object must be “split” or “smashed.” For would-be atom-smashers, the atomic nucleus thus became a target. The problem was to find a bullet small and tough enough to blast it, and a gun powerful and accurate enough to aim that bullet.

Such a “gun” was invented in 1932 by University of California’s brilliant young Ernest Orlando Lawrence. He called it a cyclotron. But the cyclotron failed to do more than chip off particles from the target nuclei, leaving the body of the nucleus intact, releasing comparatively little energy.

The Event. Sunday-supplement readers had long been warned that if ever an atom were split, the whole world might blow up. Yet when the great event occurred, only the scientific world quivered.

It happened in 1939 in the laboratory of a German scientist, Otto Hahn of the Kaiser Wilhelm Institute in Berlin.

He succeeded because he chose the right target, an atom of an extremely rare form of uranium (U 235), which he bombarded with a stream of neutrons. The explosion which occurred when the uranium atom finally split was, proportionately, the greatest man-made blast in history; it released 200 million electron-volts. But because the source and volume were so small, the shock was not enough to knock a fly off the wall. As war overtook the world, the problem of releasing atomic energy in quantity, as for a bomb, still remained unsolved.

The Real Race. For scientists and laymen alike, this week’s historic blast was the first indication of the progress made in the greatest and most-secret research race of the war. Except for a few breathless tales of mysterious walled laboratories and factories whose workers were interned for the duration, scarcely a word leaked out.

A host of famed scientists, including such bigwigs as Niels Bohr, Lawrence, Arthur Holly Compton and James B.

Conant, were enlisted in it. Hidden under the official designation “Manhattan Project,” the vast forbidden areas in Tennessee, Washington and New Mexico got top priorities not only on matériel but on scientific brains and effort.

Principal credit for the fruitful channeling of this rich source of brainpower, announced Secretary of War Stimson, belongs to “the genius and inspiration” of slight, dark Physicist J. Robert Oppenheimer, 41, of the University of California and California Institute of Technology.

Long a vanguard authority on atomic structure, he is, say his colleagues, “one of the world’s greatest geniuses, no question about it.” The Stretch. When, in March 1941, the process was discovered for manufacturing the atomic explosive, chemists feared it would take years to perfect a method of making it in quantity. Measurements accurate to 3% of one microgram (about one two-millionth the weight of a human breath) had to be established.

By 1944, grams were being measured out in place of micrograms. By last July 12, the scientists were ready to test their product. In an old ranch house on the New Mexican desert southeast of Albuquerque, a company of jittery men watched Cornell Physicist Robert Bacher assemble the first atomic bomb. At one point a vital part jammed. The scientists gasped but were coolly reassured by Bacher.

When the preliminary assembly was done, each of the expedition’s top men took over his specialized role. When all was ready the expedition waited.

The Finish. Thunder & lightning rumbled and flashed in the early morning of July 16 when the final test was to be made. The bomb was carefully mounted on a steel tower hung with instruments to record the effects of the explosion.

Over five miles away, the scientists lay flat, listening breathlessly to the time signals announced over the radio by Chicago’s Dr. Samuel K. Allison: “Minus 15 minutes, minus 14 minutes, minus 13 minutes. . . .” At “minus 45 seconds” a robot mechanism took over the controls and the watchers lived the tensest seconds of their lives.

Suddenly there was a tremendous sustained roar. In Albuquerque, 120 miles away, the sky blazed noonday-bright. The scientists close at hand looked up in time to see a huge, multicolored pillar of cloud surging up over 40,000 feet in the sky.

But where the steel tower stood, there was only a crater. The tower had completely vaporized.