In 1933, when Albert Einstein became the first staff member of the Institute for Advanced Study in Princeton, New Jersey, he was asked who he wanted to join him. The first name on his lips was a British physicist – Paul Dirac. A few months later, Dirac, at 31, became the youngest theoretician to win the physics Nobel Prize. Although he is little known today, he is quite possibly the greatest British mind of the 20th century. If Newton was the Shakespeare of British physics, Dirac was its Milton, the most fascinating and enigmatic of all our great scientists. And he now has a biography to match his talents: a wonderful book by Graham Farmelo. The story it tells is moving, sometimes comic, sometimes infinitely sad, and goes to the roots of what we mean by truth in science.
Dirac was an odd and difficult man. Born in Bristol in 1902, he had a troubled relationship with his father, and with his brother, who committed suicide. The anecdotes about his lack of empathy are legion: at St John's, the Cambridge college where he spent most of his career, he was asked where he was going on holiday. After some 20 minutes, he replied: "Why do you want to know?" On another occasion, answering questions after a lecture, an audience member said, "Dr Dirac, I didn't understand the equation on the top-right of the blackboard." Dirac said nothing. After a minute, he was asked if he'd like to answer the question. Dirac replied: "It wasn't a question, it was a comment."
Dirac's overwhelming concern was mastering not social niceties, then, but the fundamental laws of nature. As Farmelo puts it, the discovery of quantum mechanics knifed open a sack of mathematical gemstones – and it was Dirac who gathered the most diamonds. Whereas Newton spent the majority of his life researching alchemy, or Christian doctrine, Dirac was obsessed with his equations, despising subjects such as philosophy. (His verdict on Wittgenstein, a contemporary at Cambridge, was: "Awful man. Never stopped talking.")
And yet Dirac's brand of theoretical physics, and the way he saw the world, was so close to philosophy. He was convinced that the more beautiful an equation, the more likely it was to be accurate – in other words, he saw a picture of the world that was of such beauty that it had to be true.
His great equation for the electron – an improbable marriage of relativity and quantum theory – only worked if you assumed that there was such a thing as an "anti-electron". His colleagues mocked the idea, but Dirac stuck to his guns: the maths was so harmonious that reality had to reflect it. He was dramatically proved right: the anti-electron was soon discovered experimentally, and shortly after the concept of "anti-matter" became a cornerstone of physics.
Such achievements should have brought lasting fame – but, as Farmelo illustrates, Dirac made things difficult for those wanting to lionise him. When he arrived to collect the Nobel Prize in 1933, there was a marvellous kerfuffle. He and his mother sat quietly in the station's waiting room, failing to realise that the host of – increasingly alarmed – grandees lined up along the platform were there as his welcoming committee.
I had my own encounter with Dirac a few decades later. As a parliamentary candidate in his home town of Bristol, I was shocked at how obscure he had become, compared with Brunel. So I set up a prize for maths at the local school, and wrote to Dirac asking to use his name. He was pleased, and asked also for some pictures of his alma mater. When I came to St John's to deliver them, however, I saw that he had the outer door closed, which signalled that he didn't want to be disturbed.
Knowing his reputation, I was too timid to knock, and so missed my chance to meet the greatest British mind of the century. Thanks to Graham Farmelo's wonderful new book, a new generation will have the chance to realise just how foolish I was.
• Lord Waldegrave is chairman of trustees at the Science Museum.
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