Luis Alvarez will probably be remembered best not for the work in elementary particle physics that earned him the Nobel Prize in 1968 but for his work in geology: He posited the definitive theory explaining why dinosaurs became extinct.
His interest began with a rock whose layer of clay had been formed 65 million years ago. Working with his son, Walt, a geologist, and a pair of nuclear physicists, Frank Asaro and Helen Michel, Alvarez concluded "that a 10-kilometer piece of the solar system debris hit the Earth 65 million years ago and threw dust into the stratosphere that made the sky dark as midnight for several years, thereby stopping photosynthesis (preventing vegetation from growing) and so starving the animals to death."
But his theory as to the cause for the mass extinction of dinosaurs and other life forms could be seen as a postscript to this physicist's illustrious career. He was part of the team that developed the atomic bomb in Los Alamos, and he led a small group in a B-29 aircraft to monitor the energy released in the explosion of the bomb dropped on Hiroshima. He tells us that his laboratory was within days of discovering nuclear fission (that a uranium atom could be split by bombardment with neutrons) when Niels Bohr announced that German chemists had already made that discovery.
"Parts of the book may be too technical for some readers," Alvarez writes. But he encourages those readers to read around the difficult parts and still "share the human excitement of the research laboratory." A fascinating life.