Jeremy Bernstein

I had one encounter with Stephen Hawking. He came in the summer of 1989 to the Aspen Center for Physics and had the office next to mine. He travelled with an entourage with whom he could communicate with his voice synthesiser. His hands still worked well enough. He gave a full house public lecture and afterwards Sidney Coleman presided over a question session. Hawking had to type out all his answers on his voice synthesiser which took a lot of time. At one point Sidney said: 'You can have it fast or you can have it good.' If I had asked a question, it would have been: how did he come up with the idea of Hawking radiation? I have always found his paper hard going and have always marvelled at the simple result at the end. In A Brief History of Time he gives an account which explains the phenomenon but not the result.

‘The Iranian regime has committed multiple violations of the agreement,’ Donald Trump said last week. ‘For example, on two separate occasions, they have exceeded the limit of 130 metric tons of heavy water.’ In 1931, the American physical chemist Harold Urey discovered deuterium, the isotope of hydrogen that has a neutron in its nucleus along with a proton. He manufactured some ‘heavy water’ (D2O) and, I think, drank some. Heavy water remained an interesting laboratory phenomenon until the Second World War, when it took on new importance since it plays a role in the production of plutonium, which does not exist naturally on earth.

Not long after the Second World War, the scientists at Los Alamos realised that they could vastly improve the design of a nuclear bomb, making it light enough to fly on a rocket.

US presidents since John F. Kennedy have been followed everywhere by an army officer carrying a leather-bound metal Zero Halliburton briefcase. (Zero Halliburton was sold to a Japanese company in 2006, but Donald Trump hasn’t switched to an all-American manufacturer.) Inside the president’s ‘emergency satchel’, also known as the ‘nuclear football’, is a ‘black book’ containing such things as retaliatory options and the codes for launching them. The president has the power to choose any of these options and no one has the power to stop him.

In the early 1970s I wrote a profile of Albert Einstein for the New Yorker. I had known his secretary Helen Dukas since my days at the Institute for Advanced Study. She had come with him when he emigrated from Germany and lived in the Einsteins’ house in Princeton, which after his death she shared with his stepdaughter Margot. I asked if I could visit the house. She agreed. In Einstein’s study there was an etching of James Clerk Maxwell and one of Newton which had come out of its frame. This seemed symbolically correct. Helen offered to make lunch and while she was preparing the sandwiches she gave me a book to look at. It included a letter Einstein sent from Brussels to his wife Elsa in 1930.