American Scientist

A BRILLIANT DARKNESS: The Extraordinary Life and Mysterious Disappearance of Ettore Majorana, the Troubled Genius of the Nuclear Age. João Magueijo. xxii + 280 pp. Basic Books, 2009. $27.50.

Italian physicist Ettore Majorana has been an enigma for decades. A contemporary of Enrico Fermi, Majorana produced some prescient articles in the 1930s and then vanished, but not without a trace—in fact, with too many traces. The troubled Majorana, who appeared to be battling depression, had landed a coveted professorship in Naples. Yet in March 1938 he sent off a string of short and strange letters to his family and also to his new boss, the director of the Institute of Physics at the University of Naples. To a casual reader, they might appear to be suicide notes, except that the second letter to the professor in Naples tells its recipient to disregard the dour letter from the previous day, and none of the notes quite mentions suicidal intentions. The letters went out to their recipients, and then—nothing. Majorana never did show up to teach, and his family never did succeed in tracking him (or his body) down.

To this day, Italian physicists, journalists and conspiracy theorists (the three sets have some overlap) wonder what could have become of young Majorana, who was just a few months shy of his 32nd birthday when he disappeared. Had his theoretical investigations into the behavior of nuclear particles—right on the heels of the world-changing discovery of nuclear fission—convinced either Majorana himself or some other dark agents that he knew too much? Rumors began to swirl. Some said that he had faked his death and run off to a monastery, others that he had fled from Sicily to Argentina, and still others that he had become a homeless vagrant, a kind of idiot savant doing fantastically complicated computations in his head while the world’s physicists zoomed headlong toward the nuclear age.

When physicists outside of Italy think of Majorana, most remember him chiefly for his mathematical description of the neutrino, a tiny wisp of a particle that Wolfgang Pauli, back in the early 1930s, had grudgingly hypothesized might exist. Paul Dirac, the British physicist who first provided a coherent mathematical description of such a particle, stipulated that the neutrino must be distinct from its antimatter cousin, the antineutrino. In Majorana’s version, however, the neutrino and its antiparticle are one and the same. That subtle difference matters little if the neutrino has exactly zero mass—which is what physicists assumed for decades. But in 1998 convincing experimental evidence began to accumulate that the elusive neutrino—its true character as difficult to discern as that of Ettore Majorana—has some tiny but nonzero mass after all.

And so physicists are eager (some even desperate) to learn whether neutrinos obey Majorana’s equation or Dirac’s: Are neutrinos and their antiparticles identical twins, or are they more like kissing cousins? The answer to that question could unlock further mysteries or remove thorns from the side of the standard model of particle physics. Majorana neutrinos that have some mass could allow all manner of interesting but rare interactions to take place, whereas Dirac neutrinos (massive or not) would rule such subtle features out. Big stakes hang on the tiny particles: Perhaps they can shed some light on the long-standing riddle of dark matter, or explain convincingly why there is more matter than antimatter in the universe. Suddenly Majorana’s physics is on lots of people’s minds again.

The theoretical physicist João Magueijo has written an engaging, entertaining, at times witty book about Majorana and his famous neutrino. Magueijo writes in an unusually loose and candid way, and the book is filled with whimsical—yet effective—cartoons to explain the quantum dance of subatomic particles. Most of the book traces Magueijo’s efforts to sort wheat from chaff in the many Majorana stories that have accumulated over the decades. He tracks down members of the family and former colleagues, and reads all of the many snippets of Majoraniana against one another to try to tease out the most likely chain of events. The final third of the book shifts attention to more recent work, explaining why Majorana’s treatment of the neutrino may just come back to prominence within cutting-edge physics.

There are certainly things to quibble with. For example, Magueijo depicts Majorana’s friendly rival Fermi as a minor theorist of mediocre mathematical skill and little imagination—a portrait completely at odds both with the general view of Fermi and with the information contained in tens of thousands of pages of primary and secondary sources available on the Nobel laureate. Magueijo’s unconventional narrative style might also irk some readers. Certain passages linger on moments in Majorana’s life, building up dramatic tension without ever moving to a climax or conclusion. Magueijo also inserts himself squarely into the narrative, spicing the text with off-the-cuff observations and value judgments that may well make some readers chuckle and others groan. (I admit to having each reaction in turn.) Nevertheless, A Brilliant Darkness is a page-turning yarn and an accessible introduction to some deep and beautiful ideas at play in physics today.

David Kaiser is an associate professor in the Program in Science, Technology, and Society at the Massachusetts Institute of Technology, and a lecturer in MIT’s Department of Physics. He is the author of Drawing Theories Apart: The Dispersion of Feynman Diagrams in Postwar Physics (University of Chicago Press, 2005) and is currently completing a book titled How the Hippies Saved Physics (forthcoming from W. W. Norton).