Hans Bethe Article - Cornell Magazine

Hans Bethe, head of the Theoretical Physics Division at Los Alamos, neither panicked nor blamed Kistiakowsky. Instead he stayed up all night plowing through calculations. The following morning he announced that "the instrumental design was such that even a perfect implosion could not have produced oscilloscope records different from what was observed." In other words, the alarming results were meaningless. Oppenheimer fell on Bethe's calculations with relief; the panic lifted ; the countdown continued.

In this 50th anniversary year of the dawn of the Atomic Age, this anecdote displays the characteristic strengths of Han Bethe, the John Wendell Anderson professor emeritus of physics: a steadiness, which often served as an anchor for others; a thoroughness in his approach to a problem and a stamina that few could match; and a quite justified faith in his own prodigious mathematical abilities. The story is often told that Bethe works by sitting for hours at a table with a stack of blank sheets of paper on one side of him and a stack of finished sheets on the other, with one sheet in between which he is steadily filling, writing in pen without corrections. Years after Los Alamos, the physicist Richard Feynman, himself famous for his ability to perform calculations in his head, would say that he learned it from Bethe, who was "absolutely topnotch. He was nearly always able to get the answer to any problem within a percent."

One thinks of a Mozart of mathematics. And like Mozart, Bethe has always displayed a certain insouciant lack of modesty about his abilities. Once, when a friend, physicist Victor Weisskopf, asked him how long a certain calculation would take, Bethe answered cheerfully, "It would take three days for me and it will take three weeks for you!" This was not boasting, merely clear-sightedness. (Weisskopf reports that the calculation, indeed, took him three weeks.)

The same dedication to clear-sightedness makes Bethe wary of the flights of fancy, the soaring philosophical rhetoric, in which some physicists indulge. Because of this, he doesn't "give good quote," like Oppenheimer, Freeman Dyson, '47 - '48 Grad, or Stephen Hawking, and in accounts of the Manhattan Project one is struck by how little is written about him, given the importance of his position.

Bethe was born in 1906 in Strassburg (then part of Germany) and raised mainly in Frankfurt. As he told an interviewer in 1968, he was a "tender" child, who retreated from loneliness into fairy tales and numbers. He loved the latter so much that he compulsively memorized train schedules and shipping lists. As a teenager, he wavered between mathematics and physics but eventually chose the latter because, as he has said, "mathematics seemed to prove things that were obvious." He studied at the University of Munich under Arnold Sommerfeld, one of the most influential professors of theoretical physics in the world, and later took temporary positions in various universities in Germany, England and Italy.

Bethe told his biographer, Jeremy Bernstein, "The English had a much healthier attitude toward life than the Germans. The mystical element in the life philosophy of many Germans had always repelled me, and still does. In England, everything was clear and simple. I was happy." His appreciation of Enrico Fermi, with whom he worked in Rome, struck a similar note: "Fermi seemed to me at the time like the bright Italian sunshine. Clarity appeared wherever his mind took hold."

Meanwhile, back in Germany, the fogs of mystical longing were growing thicker. People were not only talking about "Jewish art" but "Jewish physics." Albert Einstein was advised to make no public appearances for his own safety. In 1931, Arnold Sommerfeld cranked up a blackboard during class to find that someone had scrawled "DAMNED JEWS!" across it, and Bethe found himself in 1932 teaching students wearing swastikas. Shortly after Hitler came to power in 1933, a law was passed forbidding employment in the civil service - which included the faculties of the state-run universities - to anyone with a Jewish parent or grandparent. Bethe had never considered himself Jewish, but his mother was a Jew, and he lost his position immediately. He took temporary refuge with Sommerfeld in Munich but finally left the country for England, eventually taking a position at Cornell University in February 1935.

Within four years Bethe had established himself as a towering figure in his field, partly through writing three monumental review articles on nuclear physics known forever after as the "Bethe Bible," and partly through methodically uncovering, via reams of patient calculations, the precise fusion reactions that power stars. (This work won him the Nobel Prize in 1967.) He married Rose Ewald in 1939, the daughter of his former professor at the Technical College of Stuttgart.

On the eve of World War II, two researchers in Berlin discovered that neutrons bombarding uranium could cause the nuclei to fission and subsequent experiments showed that this fissioning produced more neutrons. Nuclear physicists immediately saw that two things were theoretically possible: the production of atomic energy and the production of atomic bombs. But Bethe at first didn't believe it would be practically possible to build a bomb during the war. He saw enormous difficulties involved in separating the more fissionable uranium 235 isotope from the more common U-238. (He was not wrong about the difficulties.) No physicist in the table-top of physics in 1939, when the scope and equipment of physics was relatively simple, could foresee that within five years there would be 100,000 people working in a complex that included the largest building on earth, at Oak Ridge, Tennessee, on the inelegant, brute-force solution to this problem.

It was only when Bethe saw Fermi's uranium-graphite reactor pile in a squash court at the University of Chicago in 1942, and learned from Edward Teller that such a reactor could produce fissionable plutonium, that he began to see that some sort of bomb was probably workable. Oppenheimer wanted him to join the secret Manhattan Project then being set up, but Bethe first had a long talk about the morality of it all with his wife. As he told his biographer, "[Rose] asked me to consider carefully whether I really wanted to continue to work on this. Finally, I decided to do it. The fission bomb had to be done, because the Germans were presumably doing it." As he says now, "The main reason was, I felt in this way I could make the greatest contribution to the war effort. After all, nuclear physics was my field."

This article is by Brian Hall, an Ithaca-based freelance writer whose work has appeared in the New York Times Magazine and Travel Holiday. It is reprinted here with the permission of Cornell Magazine. The article appeared in the August/September 1995 issue, the 50th anniversary of the dawn of the atomic age.

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Created using Microsoft FrontPage 2002 Last modified: August 03, 2005

Created using Microsoft FrontPage 2002
Last modified: August 03, 2005