Origins

TECHNOLOGY Origins

In World War I, when the British did not dragoon their scientists as sternly as in this one, somebody asked gruff Sir Ernest Rutherford (later Lord Rutherford) if he would please stop puttering with the atom and work full time on antisubmarine devices. Rutherford answered, in effect: Gentlemen, I am trying to split the atom. If I succeed, it will be more important than the war.

He did succeed, in 1919, and he was right about its importance.

Worldwide Ferment. Some of the dazed publicity that last week followed the unveiling of the atomic bomb gave the impression that it was created from scratch, under the terrible urgency of war.

Nothing could have been farther from the fact. The urgency of war had indeed hastened the achievement. But the explosive release of atomic energy was clearly foreshadowed by the ferment of atomic physics in 1940, before the security blackout was clamped down. The experiments popping five years ago all over the world (including Japan) were based on a number of fundamental discoveries in the past half-century.

Mass & Energy. In 1896 Henri Becquerel discovered radioactivity, which is the spontaneous release of atomic energy by certain heavy metals. Becquerel had some photographic plates lying in a dark drawer near a bit of uranium; he found the plates lightstruck. His researches led to the discovery of radium by Pierre and Marie Curie, and it was by using radium for cancer therapy that man first harnessed atomic energy to his own ends.

In 1905 Albert Einstein, no experimenter, launched the idea that mass and energy are the same thing, in different states. The matter in the nucleus or core of the atom (which is practically all the matter there is) was conceived as a packet of energy in highly concentrated form.

For the conversion of mass into energy, Einstein wrote what is probably the most important equation ever devised by man: E = mc2. This means simply that energy is equal to mass multiplied by the square of the velocity of light. Light's speed is so enormous" (186,000 miles a second), and its square (self-multiplication) so much more enormous still, that one pound of matter is equal to more than ten billion kilowatt-hours of energy.

To those who then believed Einstein, his equation explained how radioactive metals could keep on shooting out particles and radiation for millions of years, and how the sun could continue shining for even longer ages. It also aroused Sunday-supplement dreams of driving an ocean liner around the world by releasing the atomic energy locked in a cupful of water.

Trigger & Key. Nitrogen's atomic nucleus was the first to succumb to human attack. Bombarding with radioactive particles, Rutherford succeeded in changing a few nitrogen atoms into oxygen.

In 1932 James Chadwick of England discovered the neutron, a particle which has no electric charge and therefore slips straight through the powerful electric shields outside and inside of heavy atoms. Soon Italy's brilliant Enrico Fermi (who has lived in the U.S. since 1939), was attacking all sorts of heavy atoms, including uranium, with neutrons. The neutron became the trigger of the atomic bomb.

In 1934 Jean-Frederic and Irene Joliot-Curie succeeded in making boron, magnesium and aluminum artificially radioactive. The atoms of these normally stable substances continued to shoot out particles for some minutes after the preliminary bombardment stopped. Artificial radioactivity is the key mechanism of the atomic bomb.

Puzzle to Fission. Late in 1938 a distinguished German chemist named Otto Hahn, of Berlin's Kaiser Wilhelm-Institute, was bombarding uranium with "slow" neutrons of low energy. As one of the end products, he identified barium. This puzzled him, but he published a diffident note on it in Naturwissenschalfen.

Hahn had been repeating experiments performed by a onetime colleague, Lise Meitner, a Jewish woman scientist who had fled from Hitler's Reich to Copenhagen. Meitner's own experiments had puzzled her--but when she saw Hahn's report she guessed that the huge uranium atom had been broken into two nearly equal fragments.

She passed this idea on to Denmark's great atomist, Niels Bohr, who was just about to leave for Princeton. Bohr told U.S. experimenters about it. They sprang to their atom-smashing machines and quickly confirmed it (TIME, Feb. 6, March 13, 1939). They also stood gallantly back while Dr. Meitner published the first notes on uranium splitting. She called it "fission," a familiar word in biology but a new term for physics.

Energy Profit. Fission was revolutionary, sensational--not only because the heaviest of all elements had been cracked wide open, but because of the tremendous energy profit. Up to then, scientists had always had to put more energy into their projectiles than was released in the breakup. Now, an explosion of about 200,000,000 electron-volts was touched off by idling neutrons of less than one electron-volt. Matter equal to about one-fifth of a neutron's mass was converted into energy according to the Einstein formula.

Reasonable Possibility. The first uranium explosions produced secondary neutrons, which in turn seemed capable of touching off uranium atoms, which would yield more neutrons, and so on. This "chain reaction" looked like the clue to a large-scale release of atomic energy., France's Joliot-Curie did in fact produce a chain reaction, but it died out after a few cycles (TIME, Feb. 12, 1940). The problem was to start one which would not dwindle but multiply.

The prospect was difficult--but hopeful. Soberly summarizing nearly 100 reports which appeared during 1939, Dr. Louis A. Turner of Princeton concluded in the Reviews of Modern Physics: "For the first time it seems that there is some reasonable possibility of utilizing the enormous nuclear energy of heavy atoms. . . . The practical difficulties can undoubtedly be overcome in time."

Shortly thereafter atomic researchers ducked behind a veil of secrecy. There the "practical difficulties" were overcome.

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