The Magic Furnace by Marcus Chown

Author:Marcus Chown [Chown, Marcus]
Language: eng
Format: azw3
ISBN: 9781448112746
Publisher: Random House
Published: 2011-09-29T16:00:00+00:00

8

A Recipe for Sunlight

HOW WE DISCOVERED THE PRECISE MANNER IN WHICH HYDROGEN IS CONVERTED INTO HELIUM INSIDE STARS.

It should not be so difficult after all to find the reaction which would just fit our old sun. I must surely be able to figure it out before dinner!

Hans Bethe (as remembered by George Gamow)

HANS BETHE’S MOTHER WAS Jewish. In 1933, therefore, when Hitler came to power, the 27-year-old physicist was instantly dismissed from his post of assistant professor at the University of Tübingen. The man who fired him, apparently without a twinge of regret, was Hans Geiger, whose alpha-scattering experiments had revealed the atomic nucleus to Rutherford.

Bethe, like Fritz Houtermans, fled to England. However, unlike his fellow countryman, he had the good fortune to obtain a post in the United States, rather than the Soviet Union. At New York’s Cornell University Bethe quickly established himself as a central figure in the rapidly advancing field of nuclear physics, writing a series of reviews of the subject which were so influential they were referred to as ‘Bethe’s Bible’. His mastery of nuclear physics would ensure that, when war with Germany came, he was chosen to head the theory division at Los Alamos, the secret laboratory charged with developing the atomic bomb.

Bethe’s interest in nuclear physics had been a down-to-earth one. He was aware of the problem of stellar energy generation, but considered the task of identifying the nuclear reactions powering the sun too speculative to waste time on. His opinion changed, however, after attending a conference in Washington DC in the spring of 1938. He would have ignored the conference had it not been for his friend, the Hungarian physicist Edward Teller. It was Teller, a fellow refugee from Europe and the man who would one day ‘father’ the American hydrogen bomb, who urged him to go. What clinched it for Bethe was that the conference was being organised by George Gamow.

Gamow, after wandering throughout Europe, had arrived in the United States in 1934 to take up a post at George Washington University. Like Bethe, he was active in down-to-earth nuclear physics. However, he had also developed a keen interest in stars, chiefly because Houtermans and Atkinson had shown his tunnelling idea to be crucial to the understanding of any nuclear reactions in the sun. It was this interest that had prompted him to organise a three-day meeting on the ‘stellar energy problem’.

Bethe had low expectations for the conference. However, as he sat listening to the astronomers describing the latest view of the conditions in stars, it struck him suddenly that he had been wrong about the stellar energy problem. With his command of nuclear physics, there was a very good chance that he would be able to identify the elusive nuclear reactions that powered the sun.

According to Gamow, it was on the train journey home to New York that Bethe discovered the reactions responsible for sunlight. Intending to solve the problem before dinner, he took out a sheet of paper and began covering it with formulae and tables of numbers.

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