The Strangest Man: The Hidden Life of Paul Dirac, Mystic of the Atom Book

Dirac was one of the most extraordinary thinkers of the 20th century - indeed, of all time - and this book makes a valiant attempt to tell you about his life. The problem is that the interesting things happened inside Dirac's head, and no one knows what was going on there. Dirac didn't like to talk unless he had something to say that he thought would be worth listening to, which was the case most of the time. When he'd come up with an idea that passed his test, he'd usually just write it down from start to finish, no corrections, no crossings out. As one of his colleagues said, it was as though a chunk of marble had fallen from Olympus. During a period of about ten years in the 20s and early 30s, he was phenomenally productive and played a major role in establishing the new field of quantum mechanics.

His greatest triumph was hypothesizing the existence of antimatter, now a word everyone knows. He didn't look at any experimental data: he just messed around with the equations for the electron and found a way to manipulate them into a form which seemed to show that there was another thing that was like an electron, but in some sense opposite in nature. People, including Dirac, were uncertain about what that actually meant, but the derivation was so elegant that he was sure it meant something. Less than five years later, experimentalists studying cosmic rays found tracks which could only be explained as being caused by a particle that behaved like a positively charged electron. When electrons and "positrons" met, they mutually annihilated. It turned out that antimatter existed; Dirac was awarded the Nobel Prize at the age of 31.

Dirac himself didn't really know how he'd done it. He started talking about the importance of beauty and mathematical elegance in physical theories. The Dirac equation is indeed very beautiful and elegant, everyone agreed on that. But there was another, pragmatic side to Dirac, coming from his early training as an engineer. Sometimes the engineer seemed to take over, and he'd do apparently unsound things that would annoy the mathematical purists. The most famous example was the Dirac delta-function, which didn't become mathematically respectable for decades; Dirac just knew it was the right way, and cited analogies in engineering when he had to defend it. Later in life, he moved entirely towards elegant, mathematical modes of thinking, criticising the new mainstream of quantum field theory as being ugly and unsound, and after a while the miraculous discoveries stopped. Perhaps he needed to keep on thinking pragmatically from time to time; or perhaps he'd just got too old, or marriage somehow made him lose his focus.

Dirac was clearly autistic, and like many autistic people he was often unaware of social conventions. There are a thousand amusing stories about him. (George Gamow said that amusing stories about famous scientists are generally not true, except in the case of Dirac, when they are always true). But the stories aren't the important thing, it's his way of thinking. As with Wolfgang Amadeus Mozart and Bobby Fischer, so many people have tried to figure out how to imitate the tantalisingly pure, simple style, but there's only ever going to be one of them.