People love a good prediction. One of the most important features of a scientific theory is that it can predict the results of experiments nobody has yet performed. Even though there isn’t much of a testable theory behind it, lots of people still read daily astrology columns— and a finalist for yesterday’s birthday person was Alan Leo, the “father of modern astrology.” But he didn’t make the cut so you’ll have to look him up on your own. Today we’re talking about somebody with a vastly more scientific bona fides: Paul Dirac. He was a theoretical physicist who helped found quantum mechanics, and is the author of the Dirac equation, which predicted that if experimental physicists looked in the right places in the right ways, they’d find antimatter. And they did.
Dirac was born in 1902 in Bristol, England. His surname sounds French, not English, and that comes from his father’s ancestry — Charles Dirac, Paul’s dad, was an immigrant from Switzerland, and traced his family back into France. Another side effect of his father’s history was that the Dirac family spoke French at home, and Paul Dirac remained bilingual for his whole life.
In school, Dirac didn’t initially seem like he was going to become virtually the equal of Albert Einstein (in fact, some physicists consider Dirac’s contributions to be greater than Einstein’s). He attended the Merchant Venturer’s Technical College, which taught bricklaying, metalwork, and shoemaking, among other subjects. He probably attended that school because it’s where his father taught French. But Dirac later said he was grateful to have studied those things instead of the typical English classical curriculum. That school was not university-level in spite of the name “college,” and he later attended the University of Bristol to study electrical engineering. When he completed his degree in 1921, England was suffering in a depression after World War I and there were no engineering jobs available, so Dirac stayed at the university to study math. He earned another degree in 1923, and attended Cambridge, on a scholarship, to pursue a PhD in physics. His thesis on quantum mechanics was the first one ever submitted anywhere, and earned him his doctorate in 1926.
He continued his research in Copenhagen, Göttingen (in Germany), and in the US at the University of Wisconsin and in Princeton. He was becoming known for his brilliance, as well as for his eccentricities. He didn’t say much, and when he did he spoke slowly. His colleagues created the unit called the “dirac,” which was “one word per hour.” He kept a diary, and wrote that he concentrated only on one thing: his research. Other than that, he could think of only one activity he enjoyed, which was taking walks by himself every Sunday. He appeared to be very shy, and was uncomfortable in social situations. When he and Werner Heisenberg sailed on a liner to a conference in Japan in 1929, the two were outwardly matched (in their twenties, unmarried, and otherwise similar) but Heisenberg enjoyed dancing and flirting while Dirac hung back. “Why do you dance?” he asked Heisenberg, who replied “When there are nice girls, it is a pleasure.” Dirac thought about that for a while and eventually said “But how do you know beforehand that the girls are nice?”
Dirac met the physicist Richard Feynman at another conference, and stood silent for a long time before thinking of something to say. Which was “I have an equation. Do you have one too?” Dirac did indeed have an equation — in fact, he contributed a number of equations that are still fundamental to math and physics, including the Dirac algebra, the Dirac operator, the Dirac delta function, and of course the monumental Dirac equation. He was always modest about his work, though, and often called the contributions named after him by someone else’s name, such as Heisenberg, Fermi, or Bose. He also coined the terms “fermion” (after Fermi) and “boson” (after Bose), as well as “quantum electrodynamics,” a field that he actually created.
In addition to predicting the discovery of antimatter, Dirac proposed the existence of a magnetic monopole (which has probably not yet been found), gravitational waves and the “graviton” (another term he coined), and his work anticipated string theory, which didn’t arrive until the 1960s.
Dirac received the Nobel Prize in physics in 1933, and just about every other award you can think of as well. He was offered a knighthood in England but declined for an odd reason: he didn’t want to be addressed by his first name, as in “Sir Paul.” In Bristol, there is both a plaque commemorating his birthplace as well as “Dirac Road” close by. there is also a commemorative plaque with his name and the Dirac equation in Westminster Abbey. There is a Paul Dirac Library at Florida State University, where he taught, Paul Dirac Drive in Tallahassee, Florida (where the National High Magnetic Field Laboratory is located), and two different institutes of physics award annual Paul Dirac medals for excellence. Stephen Hawking and Roger Penrose are both past winners. Nobody would have predicted a career like Dirac’s when he was studying how to make shoes as a teenager.
