Powerful Brain

One of Nazi Germany's greatest gifts to the U. S. is Professor Hans Albrecht Bethe of Cornell University. A brilliant theorist in atomic physics, modest, demure Dr. Bethe probes straight to the core of an abstruse problem, then brings to bear on that core his remarkable mathematical equipment so that the answer comes leap ing out like a weasel out of a smoked hole. Educated at Kiel, Frankfort and Munich, Hans Bethe, whose mother is Jewish, was holding a post at Munich when the Nazis came in. He left Germany in 1933, taught and researched in England for a while, went to Cornell in 1935. Author of five major treatises and some 50 miscellaneous articles on nuclear physics, he makes it hard for U. S. physicists and physics journals to keep up with him. Like most theoretical physicists at the height of their powers, he is young -- only 33.

Hans Albrecht Bethe likes skiing, economics and riding on trains, but spends most of his time mulling over theoretical physics. Last summer he married Rose Ewald, daughter of a distinguished Ger man theoretical physicist exiled in Ireland. At Cornell, Dr. Bethe lives with his wife and mother in a cottage in Cayuga Heights. He does most of his work in an easy chair in the living room. Tools : a stack of reference books, a batch of paper, a slide rule, a fountain pen, a powerful brain.

Dr. Bethe figured out that the shape of the deuteron (nucleus of the heavy hydrogen atom) should not be spherical but oval like a football--which agreed with the experimental findings of Professor Isidor Isaac Rabi & associates at Columbia. Year ago Dr. Bethe was hailed by astrophysicists for figuring out that carbon must be the stuff that enables the sun to turn fragments of hydrogen atoms into sunshine (TIME, Feb. 27). Lately he has been working on the function in the atom's nucleus of a particle called the "mesotron," which weighs about 200 times as much as an electron, about one-ninth as much as a proton or a neutron. His findings, completed last week, will shortly be published in Physical Review.

In 1937 Carl David Anderson of Caltech announced the existence of an intermediate particle, apparently created about ten miles up in the air by cosmic ray impacts, and its existence was also vouched for by Street & Stevenson of Harvard. The particle was variously called the "X-particle," the "heavy electron"' (a misnomer, since it was not an electron), the "barytron" (also a misnomer, because it means "heavy particle," whereas the particle is lighter than a proton). A name meaning "intermediate particle" was clearly in order, and so practically all U. S. physicists now call it the "mesotron" or "meson."

The binding force that holds atomic nuclei together (and hence keeps the universe from exploding into a monstrous, formless cloud of atomic dust) is a powerful attraction between protons and neutrons in the atomic nucleus. Dr. Bethe finds that the transmitter of this force is none other than the mesotron, which seems not to be a permanent part of the nucleus but to appear and disappear as needed. In other words, when a nuclear proton wants to transfer a package of energy to another proton or to a neutron, it calls into existence a mesotron, which does the job and then vanishes.

Dr. Bethe estimates that to knock a mesotron out of a nucleus would require a projectile of 80 to 100 million electron-volts. Cosmic ray particles, whose energies run far up into billions of electron-volts, can thus turn mesotrons loose in the upper air, but so far no man-made atom-smasher has enough punch. However, when the huge cyclotron planned by Ernest Orlando Lawrence of the University of California gets going, man may be able to knock mesotrons out of nuclei according to the Bethe theory.

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