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

Paul Adrien Maurice Dirac was born in 1902 in Bristol, England. His father, Charles, was a Swiss-French immigrant who made his living as a French teacher at a local school and as a private tutor in French. His mother, Florence (Flo), had given up her job as a librarian upon marrying Charles. The young Paul and his older brother Felix found themselves growing up in a very unusual, verging upon bizarre, home environment. Their father was as strict a disciplinarian at home as in the schoolroom, and spoke only French to his children, requiring them to answer in that language and abruptly correcting them if they committed any faute de français. Flo spoke to the children only in English, and since the Diracs rarely received visitors at home, before going to school Paul got the idea that men and women spoke different languages. At dinner time Charles and Paul would eat in the dining room, speaking French exclusively (with any error swiftly chastised) while Flo, Felix, and younger daughter Betty ate in the kitchen, speaking English. Paul quickly learned that the less he said, the fewer opportunities for error and humiliation, and he traced his famous reputation for taciturnity to his childhood experience.(It should be noted that the only account we have of Dirac's childhood experience comes from himself, much later in life. He made no attempt to conceal the extent he despised his father [who was respected by his colleagues and acquaintances in Bristol], and there is no way to know whether Paul exaggerated or embroidered upon the circumstances of his childhood.)After a primary education in which he was regarded as a sound but not exceptional pupil, Paul followed his brother Felix into the Merchant Venturers' School, a Bristol technical school ranked among the finest in the country. There he quickly distinguished himself, ranking near the top in most subjects. The instruction was intensely practical, eschewing Latin, Greek, and music in favour of mathematics, science, geometric and mechanical drawing, and practical skills such as operating machine tools. Dirac learned physics and mathematics with the engineer's eye to “getting the answer out” as opposed to finding the most elegant solution to the problem. He then pursued his engineering studies at Bristol University, where he excelled in mathematics but struggled with experiments.Dirac graduated with a first-class honours degree in engineering, only to find the British economy in a terrible post-war depression, the worst economic downturn since the start of the Industrial Revolution. Unable to find employment as an engineer, he returned to Bristol University to do a second degree in mathematics, where it was arranged he could skip the first year of the program and pay no tuition fees. Dirac quickly established himself as the star of the mathematics programme, and also attended lectures about the enigmatic quantum theory.His father had been working in the background to secure a position at Cambridge for Paul, and after cobbling together scholarships and a gift from his father, Dirac arrived at the university in October 1923 to pursue a doctorate in theoretical physics. Dirac would already have seemed strange to his fellow students. While most were scions of the upper class, classically trained, with plummy accents, Dirac knew no Latin or Greek, spoke with a Bristol accent, and approached problems as an engineer or mathematician, not a physicist. He had hoped to study Einstein's general relativity, the discovery of which had first interested him in theoretical physics, but his supervisor was interested in quantum mechanics and directed his work into that field.It was an auspicious time for a talented researcher to undertake work in quantum theory. The “old quantum theory”, elaborated in the early years of the 20th century, had explained puzzles like the distribution of energy in heat radiation and the photoelectric effect, but by the 1920s it was clear that nature was much more subtle. For example, the original quantum theory failed to explain even the spectral lines of hydrogen, the simplest atom. Dirac began working on modest questions related to quantum theory, but his life was changed when he read Heisenberg's 1925 paper which is now considered one of the pillars of the new quantum mechanics. After initially dismissing the paper as overly complicated and artificial, he came to believe that it pointed the way forward, dismissing Bohr's concept of atoms like little solar systems in favour of a probability density function which gives the probability an electron will be observed in a given position. This represented not just a change in the model of the atom but the discarding entirely of models in favour of a mathematical formulation which permitted calculating what could be observed without providing any mechanism whatsoever explaining how it worked.After reading and fully appreciating the significance of Heisenberg's work, Dirac embarked on one of the most productive bursts of discovery in the history of modern physics. Between 1925 and 1933 he published one foundational paper after another. His Ph.D. in 1926, the first granted by Cambridge for work in quantum mechanics, linked Heisenberg's theory to the classical mechanics he had learned as an engineer and provided a framework which made Heisenberg's work more accessible. Scholarly writing did not come easily to Dirac, but he mastered the art to such an extent that his papers are still read today as examples of pellucid exposition. At a time when many contributions to quantum mechanics were rough-edged and difficult to understand even by specialists, Dirac's papers were, in the words of Freeman Dyson, “like exquisitely carved marble statues falling out of the sky, one after another.”In 1928, Dirac took the first step to unify quantum mechanics and special relativity in the Dirac equation. The consequences of this equation led Dirac to predict the existence of a positively-charged electron, which had never been observed. This was the first time a theoretical physicist had predicted the existence of a new particle. This “positron” was observed in debris from cosmic ray collisions in 1932. The Dirac equation also interpreted the spin (angular momentum) of particles as a relativistic phenomenon.Dirac, along with Enrico Fermi, elaborated the statistics of particles with half-integral spin (now called “fermions”). The behaviour of ensembles of one such particle, the electron, is essential to the devices you use to read this article. He took the first steps toward a relativistic theory of light and matter and coined the name, “quantum electrodynamics”, for the field, but never found a theory sufficiently simple and beautiful to satisfy himself. He published  The Principles of Quantum Mechanics  in 1930, for many years the standard textbook on the subject and still read today. He worked out the theory of magnetic monopoles (not detected to this date) and speculated on the origin and possible links between large numbers in physics and cosmology.The significance of Dirac's work was recognised at the time. He was elected a Fellow of the Royal Society in 1930, became the Lucasian Professor of Mathematics (Newton's chair) at Cambridge in 1932, and shared the Nobel Prize in Physics for 1933 with Erwin Schrödinger. After rejecting a knighthood because he disliked being addressed by his first name, he was awarded the Order of Merit in 1973. He is commemorated by a plaque in Westminster Abbey, close to that of Newton; the plaque bears his name and the Dirac equation, the only equation so honoured.Many physicists consider Dirac the second greatest theoretical physicist of the 20th century, after Einstein. While Einstein produced great leaps of intellectual achievement in fields neglected by others, Dirac, working alone, contributed to the grand edifice of quantum mechanics, which occupied many of the most talented theorists of a generation. You have to dig a bit deeper into the history of quantum mechanics to fully appreciate Dirac's achievement, which probably accounts for his name not being as well known as it deserves.There is much more to Dirac, all described in this extensively-documented scientific biography. While declining to join the British atomic weapons project during World War II because he refused to work as part of a collaboration, he spent much of the war doing consulting work for the project on his own, including inventing a new technique for isotope separation. (Dirac's process proved less efficient that those eventually chosen by the Manhattan project and was not used.) As an extreme introvert, nobody expected him to ever marry, and he astonished even his closest associates when he married the sister of his fellow physicist Eugene Wigner, Manci, a Hungarian divorcée with two children by her first husband. Manci was as extroverted as Dirac was reserved, and their marriage in 1937 lasted until Dirac's death in 1984. They had two daughters together, and lived a remarkably normal family life. Dirac, who disdained philosophy in his early years, became intensely interested in the philosophy of science later in life, even arguing that mathematical beauty, not experimental results, could best guide theorists to the best expression of the laws of nature.Paul Dirac was a very complicated man, and this is a complicated and occasionally self-contradictory biography (but the contradiction is in the subject's life, not the fault of the biographer). This book provides a glimpse of a unique intellect whom even many of his closest associates never really felt they completely knew.

The title of Farmelo’s book comes from Niels Bohr, who told a colleague that Paul Dirac was “the strangest man” to ever visit Bohr’s institute in Cophenhagen. Bohr’s comments related not only to Dirac’s unusually spare social interaction style but also to his iconoclastic style of thinking. In a field that is historically dense with collaborations and exchanges of findings and methods, Dirac was an extreme outlier, as someone who rarely talked at all, infamous for one word responses even in conversations with colleagues about scientific matters.Farmelo blends the story of Dirac’s odd personality and quirky behavior with the story of Dirac the physicist. After all, his “strangeness” is a dominant attribute of both his personal life and his scientific activity.He starts with Dirac’s relationship to his father, Charles Dirac. Charles Dirac was a strict, controlling father. He enforced a hard work ethic, with little social life for Paul, his brother Felix, and his sister, Betty. Felix committed suicide relatively early in his adult life, apparently over frustration with his lack of achievement. Betty clung to the family, looking after her father and mother, Flo, until marrying in her 30s.Paul never lost his resentment over his father’s tight controlling hand. Later in life, he would voice that resentment, sometimes surprising friends and even bare acquaintances, breaking his regular silence with a diatribe against his father’s treatment of him. As he grew older, and especially in his marriage to the Hungarian sister of Eugene Wigner, Manci, he seems to have freed himself to some degree, finding that he could enjoy hobbies like mountain-climbing and swimming. But he maintained an odd, withdrawn character throughout his life, customarily sitting in silence in both scientific discussions and in social situations.Paul’s mother, Flo, was also seemingly hemmed in by Charles’ strong hand. Their marriage deteriorated but ended only with Charles’ death, and long before that she came to look to Paul as her primary emotional support. The combination of a controlling father and a clinging mother put Paul in a kind of vice, no doubt partially responsible for his odd personality.Then there is Dirac the scientist. He was a mathematical physicist, a theorist of a pure kind. And it is that mathematical purity that may be his most profound legacy as a scientist. It is certainly a central theme of Farmelo’s account of his life.Dirac was propelled by mathematics. With a background also in engineering, he certainly was attentive to the need to tie mathematical speculation back to verifiable observations, but it was the math that moved his thoughts.Farmelo quotes Dirac — “The most powerful method of advance that can be suggested at present is to employ all the resources of pure mathematics to attempts to perfect and generalise the mathematical formalism that forms the existing basis of theoretical physics, and after each such success in this direction, to try to interpret the new mathematical features in terms of physical entities . . . “It would be hard to say that Dirac was the first physicist to take his lead from pure, abstract mathematics — after all, the debate over the role of abstract theory vs. experiment and observation goes back to Descartes and Bacon. But it would be just as hard to find a stronger proponent for going wherever the math leads, and then picking up the thread of reality in its wake.In fact, maybe Dirac’s best known original contribution — anti-matter — was a mathematical construction. It took significant time before his speculations could be confirmed in observations of cosmic rays at Caltech and then by his colleagues at the Cavendish Labs at Cambridge.Farmelo stresses Dirac’s insistence that good theory in physics meet a criterion of “mathematical beauty”. “Beauty’ here is somewhat ironically undefined, for someone as meticulous as Dirac in determining the meaning of any theoretical terms. But it relates essentially to simplicity and universality, traceable back to Dirac’s early reading of John Stuart Mill’s A System of Logic — something that seemed to have strongly influenced him throughout his career.Another quote serves to state how important the role of beauty in theory was for Dirac — “It is more important to have beauty in one’s equations than to have them fit experiment.” Despite his atheism, it’s hard not to attribute a kind of faith to Dirac, that the universe itself is “beautiful”, that it be describable in simple, clear terms, because the universe just is a mathematical entity.Despite Dirac’s eccentric social behavior he was at the center of the quantum revolution in physics. I realized I had never appreciate how many theoretical contributions he made, not only in new, original concepts, like antimatter, but also in pushing existing theory to meet his mathematical standards. He worked directly with all of the leading physicists of his time, a regular visitor to the labs of Bohr in Copenhagen and Born and Heisenberg in Gottingen, as well as circulating among the theoretical and experimental physics groups at his own Cambridge. Later in life, he was a frequent visitor to the Institute for Advanced Study, where Einstein and others sought him for a permanent position.Farmelo’s writing is easy, relatively non-technical, even though this is definitely not a “page-turner”. He has the physics credentials to tell us the science side, but it is as much personal biography as intellectual biography. You won’t find a lot of equations, or even complex technical discussion. Yet I think Farmelo did a good job of going to the depth necessary to make it clear that such concepts as anti-matter evolved, in Dirac’s thought, through a compelling mathematical path rather than as blue sky speculations. This might be the greatest strength of his writing.

This is the best biography I have ever had the privilege to read, I have heard on occasion of Paul Dirac but never imagined how brilliant the man was? Graham Farmilo does an excellent job of giving us a brilliant overview of Dirac's life from his humble beginnings in Bristol to his Cambridge education and subsequent Nobel prize in physics.The brilliant man was way ahead of his time, too clever by far. I was fascinated with his strange behaviour and often had a chuckle at some of his blunt remarks to others.Dirac was one of a number of great physicists who gave us the beginnings of quantum mechanics during the first few decades of the 20th century, his friendships with Kapitza, Bohr, Schrodinger, Heisenberg and many others are well documented here.I can not recommend this book enough, Dirac was the strangest man yes but more importantly he was a quantum genius and one of Britain's greatest ever scientist without a doubt.

An engrossing read. Farmelo certainly picked a hard nut to crack in writing about Dirac for a lay audience, in terms both of Dirac personally and of the complexity of his work. Unusually for a scientific book, I couldn't put it down! It covers the purely biographical aspects without skipping the harder conceptual material of the physics. For the most part the author does a good job of tracing the development of quantum physics, the math and Dirac's place within it, without giving the impression of talking down to the layman. I am always interested in the early biography of creative people, showing how they developed and kindled their creative interests. There is the additional element in science of discovering how the individual fitted in to what has become very much a collective enterprise. Farmelo's treatment of this succeeded brilliantly. It's interesting to note how even extreme individualists like Dirac could only develop their ideas through interaction (either personal or through published material) with their peers. Later in his career, when the creative fires were dissipating, Dirac (and the same goes for Einstein and others) usually found themselves at variance with the cutting edge scientists of the new generation. Indeed, the later biography tends to run into a series of academic meetings or family history which is only of interest to the curious. The baubles and honours tend to arrive just when the creative fires are damping down! The speculation about Dirac's psychology and possible autism at the end of the book rounded off a fascinating portrait - it is good that Farmelo did not duck the issue. The fact that Dirac was an unusually high functioning individual even with these characteristics does not diminish their relevance. Indeed, quite possibly the intenser focus and logic associated with them was integral to the evolution of his talent. We could do with more scientific biographies like this. Great achievement.

Biographies vary greatly, from the unimaginative hagiography via simple chronologies through to intellectually penetrating studies which bring their chosen subject alive, whatever previous knowledge the reader might have of the subject. Graham Farmelo's book about Paul Dirac - the undeservedly little-known Bristol-born theoretical physicist is a prime exemplar of the last of these. Farmelo expounds joyfully and perceptively on the life of this man, who surely ranks with the all-time greats in the understanding of the physical universe, names such as Einstein and Newton being almost household names in today's woefully science-ignorant society. The life of a ground-breaking scientist such as Dirac must necessarily be expressed using some understanding of his subject, but Farmelo positively delights in providing his readers with what is needed in this, enlightening the intelligent non-scientist without talking down to the expert. Dirac was, in his most productive years, an archetypal non-communicator - taken indeed to an extreme. Farmelo's researches are particularly meticulous, and he brings the various strands of testimony together in a considered way. Having been a research physicist, albeit an experimentalist with a pathetic grasp of mathematics, I found his exposition illuminating, and even an aid to exploring the inter-relationships between the scientists with whom I'd interacted. This is a superb book, even to its title, which derives from a (probably offhand) comment by Niels Bohr.

I'd heard Dirac's name mentioned in science programmes, but never really heard much else about him. Clearly he is a crucial character to mathematicians and scientists, neither of which applies to me, but he would also have been a fascinating study for psychiatrists. I found much of Farmelo's description of Dirac's work totally beyond my understanding, but I realised that without him modern science would not have moved into sub-atomic realms. What I found more interesting was the family background, the effect of his parents' incompatibility, the distinctions made between the siblings and Dirac's reluctance to engage in social occasions which required "small talk". This is a man who rarely started a conversation with anyone, and couldn't maintain a conversation unless it was about his work, but despite this he formed very strong friendships which later led to his involvement with campaigning for the release of colleagues who had been "retained" by the Soviet Union. Dirac knew everyone during what seems to have been a Golden Age of Science from the '30s onwards, Einstein, Oppenheimer and those who went on to develop the Atom Bomb. This is not the easiest book to read, and needs some concentration, but it is well worth the effort to learn about a man who was a colossus in his field, but who was in many ways a very isolated rather sad character.

Paul Dirac is probably the most important theoretical physicist that Britain has ever produced. It's a pity that so few people in Britain, or indeed in Bristol where he grew up, have ever heard of him.Yet, along with Einstein, Eisenberg, Pauli and Schrodinger, he was a central, pioneering figure in quantum physics. Graham Farmelo is an excellent writer and he has done a brilliant job describing the life of this mercurial genius.