One Cubit the More
Jeremy Bernstein · Remembering Oppenheimer
With the death of Stephen Hawking and the discussion it produced on black holes it was a little surprising that there was little or no mention of the man who created the subject, J. Robert Oppenheimer, who died in 1967 at the age of 62. He often said that the J stood for nothing, but I have a copy of his birth certificate on which his first name is given as ‘Julius’. In his day Oppenheimer was the most celebrated physicist in the United States. His portrait had been on the cover of Time magazine and he was on first-name terms with much of the Washington establishment, until he lost his security clearance in 1954.
It was said by people who had known him before that the experience changed him profoundly and he appeared diminished. He did not appear diminished to me when when I arrived at the Institute for Advanced Study in Princeton in 1957 and was ushered into his office. The first thing he asked me was what was ‘new and firm’ in physics. I was spared trying to give an answer when his phone rang. It was from his wife. ‘It was Kitty,’ he said when he hung up. ‘She has been drinking again.’
Oppenheimer did probably his most notable piece of physics in 1939 with his student Hartland Snyder. They invented black holes, although the name was coined decades later by John Wheeler. The subject got its start in 1916 when the German astronomer Karl Schwarzschild, serving on the Russian Front, found an exact solution to Einstein’s gravitational equations for a symmetric spherical mass. But the Schwarzschild solution appears to have a problem: at the surface of the sphere, the solutions appear to blow up – the Schwarzschild ‘singularity’. Much later it was shown that this is not a real singularity but an artifact of the way Schwarzschild wrote his solution. But it was enough to convince Einstein that the solution was unphysical and he wrote a paper showing that particles moving around a circle with the Schwarzschild radius had to move faster than the speed of light.
Oppenheimer and Snyder asked what would happen if you had a mass large enough for the sphere to collapse. What would this look like from the outside? They noted that a clock attached to the surface of the sphere would appear to an external observer to be moving slower and slower until at the Schwarzschild surface it froze. This is what happens when neutron stars collapse into black holes. Oppenheimer and Snyder noted that no radiation can escape from the interior of a collapsed sphere. At the time they wrote their paper this was pure speculation, but it was the received wisdom until the work of Hawking.
After war broke out, theoretical physics was put on hold for the atomic bomb and not really resumed until after the war. In 1947 Oppenheimer was made the director of the Institute at Princeton.
Along with his father’s money he had inherited two Van Goghs, one of which was in the living room in his house. As I was leaving his office he gave me a vague invitation to visit to look at the painting; I later saw it at a party at his house. He was a man of fashion. During the winter he wore a Loden coat made for him by the Princeton bespoke tailor Langrock. The owner, Mr Decker, if he knew you were from the Institute, would show you an autographed picture of Oppenheimer.
He was also a man of fashion in physics. Freeman Dyson has described how Oppenheimer almost reduced him to tears in a seminar when he tried to explain Feynman diagrams. They were not yet fashionable – and until Hawking, black holes weren’t fashionable either. Wheeler once told me that when he tried to discuss them with Oppenheimer, he simply turned his back and walked away.
In my second year at the Institute, a little tired of physics, I was summoned to Oppenheimer’s office for a ‘confessional’. He asked me what I had been doing. I said I was reading Proust. He said that when he was my age he had taken a bicycle trip on Corsica and every night read Proust by flashlight.
After I left the Institute and was living in New York, Oppenheimer came to town. Mal Ruderman, who taught at Columbia, called me to say that Oppie was asking everyone if they knew the source of the phrase ‘One Cubit the More’, which he was using as the title for a lecture he was about to give. I had no idea but I called Robert Merton, who identified the passage in the New Testament. That evening I went to the Algonquin for a drink. An elevator door opened and there were Oppenheimer and his wife. Without even saying hello he said: ‘Your father is a rabbi so you should know where “One Cubit the More” comes from.’ He had the wrong testament for my father, but I immediately gave the answer. He looked at me very strangely. I never explained.