Ask people to name a famous early-20th century physicist and you'll get mostly Einsteins, with maybe the odd Schrödinger or Heisenberg thrown in. It's unlikely anyone will say Paul Dirac, yet the Bristol-born scientist was at least as important to the development of modern physics as the latter two, and was arguably equal to Einstein in terms of the mindset change that his ground-breaking and revolutionary work introduced.
Essentially the founder of quantum mechanics, Dirac was a deeply odd character, a monosyllabic recluse who had eyes only for the beauty of mathematics and the subatomic world that his mind-boggling equations describe. This exhaustive biography makes an argument for Dirac's numerical brilliance and social awkwardness being attributable to undiagnosed high-functioning autism, but in his lifetime he was simply regarded by his peers as one of the greatest minds ever to tackle physics.
The reasons for Dirac's lack of celebrity compared to Einstein are twofold. On the one hand his desire to avoid the limelight was compulsive. He turned down honours from the Queen and only accepted his Nobel Prize in person when a colleague suggested it would garner more attention if he refused. The other reason is that Dirac's physics is harder to grasp than Einstein's. E=mc2 is a lot easier to fit on a T-shirt than the Dirac equation describing the behaviour of an electron, which contains over a dozen terms, three sets of brackets and half the Greek alphabet. That equation was a mathematically elegant way of combining what was already known about subatomic particles with Einstein's theory of relativity. One of the shocking results from this work, published in 1928, was that it predicted the existence of antiparticles, which transformed physics when their existence was confirmed by the experimental observation of cosmic rays four years later.
Born in 1902, Dirac was only in his mid-twenties when he came up with this shining star of his career, but he'd already made his name in the world of theoretical physics with a string of audacious but complex papers on various aspects of the subatomic world. Prior to that, his early life was marred by an extremely difficult upbringing at the hands of a domineering father and suffocating mother. Graham Farmelo has had access to a huge raft of family papers and they reveal that Dirac suffered extreme physical discomfort and emotional manipulation, factors that no doubt contributed to his unusual mental state.
But for all that Dirac was a loner, he was also part of an extraordinary time in physics. During the 1920s and 1930s there was an explosion of new thinking about the origins of the universe, the structure of atoms, events at close to light speed, and Farmelo does a good job of conjuring up the heady atmosphere at the academic centres of Cambridge, Göttingen in Germany and Copenhagen, where a gaggle of young men including Schrödinger, Heisenberg, Niels Bohr and Wolfgang Pauli were vying for bragging rights, arguing over theories in beer-soaked halls and winding each other up at conferences. Dirac was a part of this scene but always apart, viewed as a brilliant but strange fish by his more outgoing contemporaries.
There's a problem with writing a comprehensive biography of such a guarded figure. Dirac's best physics was behind him by his early thirties, and his career a slow decline from winning the Nobel Prize in 1933. With nothing in the way of extracurricular interests or even discernible personality to work with, Farmelo is left to describe Dirac's nomadic wanderings from campus to campus, only the occasional interesting development to spark the reader's interest.
One such was his unlikely marriage to Margit Wigner, the sister of a Hungarian colleague, in 1937. She was an overbearing and spoilt woman, but Dirac nevertheless seemed to love her in his own distant way, even if their relationship did become fractious as the years wore on.
The other interesting development in Dirac's life was the Second World War, during which he worked on the British equivalent of the Manhattan Project to develop the atomic bomb.
True to form, however, Dirac's engagement with the war effort was marginal and he resented being sidetracked from his own sublime theories. Throughout his whole career he showed no interest in the practical applications of his work, and was concerned only with the underlying beauty of his abstract notions.
As his theories were built upon by the next generation of young physicists, Dirac became increasingly isolated and reactionary. He dismissed their work as mathematically ugly (the worst insult he could imagine), this despite the new theories' better match with experimental results.
Dirac remained a truly strange man until his death in 1984, but his work nevertheless deserves to be better known, something that this biography goes some way to correct.
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