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Journalism of Courage
How does the sun shine? It is perhaps one of the first questions a curious child asks about the world, and one that has impelled many a curious child to physics. And, until 1938, it was something that no one could satisfactorily explain. Hans Bethe did so, along with much else, in a long and fruitful career. He was the last of a generation of physicists who changed the world: first in the 1920s and 1930s, by coming up with the entirely new theory of quantum mechanics, and then in the 1940s by proving their relevance in the harshest way imaginable 8212; by creating the atomic bomb.
Bethe was famous for his ability to make calculations quickly, a useful talent in the days before computers. It was this that allowed him, in a mere six months, to figure out a problem that had foxed other physicists, and explain what drove nuclear fusion the process by which two atomic nuclei join and release energy in the core of the sun. His colleagues could not understand how, as the temperatures of stars increased, they very rapidly became more luminous, so that a star that was ten times as hot would be thousands of times as bright. Bethe saw that only a chain of six reactions, in which carbon acted as a catalyst for the fusion of two hydrogen atoms, would explain what scientists were observing. He was to win the Nobel prize for his calculations.
Excerpted from an obituary from 8216;The Economist8217;, March 18
