American physicist whose eclectic career spanned nuclear weapons, particle physics, palaeontology and forensic investigation. He won the Nobel prize in physics in 1968 for his work designing a new generation of bubble chambers—giant vats of liquid hydrogen in which the paths of individual particles could be observed and photographed. His award citation was the longest ever for a Nobel prize in physics, a record that stood until 2013.
His father and paternal grandfather, an immigrant from Spain, were both doctors. A precocious student who completed his maths exams in pen rather than pencil, he graduated from high school at 17 and enrolled at the University of Chicago in 1928.
Alvarez developed airborne radars sometimes credited with winning the second world war; the same technology enabled the Berlin airlift. He oversaw the design of the plutonium bomb that destroyed Nagasaki in August 1945 as part of the Manhattan Project.
He clashed with J. Robert Oppenheimer, the Manhattan Project's scientific director, and was one of Oppenheimer's most persistent critics during the 1954 hearing that led to the revocation of Oppenheimer's security clearance. Alvarez considered the development of a thermonuclear bomb to be a national priority; his biographer attributes the feud to Oppenheimer's post-war change of heart on atomic energy for military use.
Beyond physics, Alvarez was described by his biographer Alec Nevala-Lee as "the world's foremost scientific detective". He investigated the assassination of John F. Kennedy, looked into unidentified flying objects and searched the pyramids of Giza for hidden chambers.
Perhaps his best-remembered contribution is the theory, developed alongside his son, that the impact of an asteroid 65m years ago drove the dinosaurs to extinction. The theory was widely accepted only after his death.
His combination of ambition, intellect and self-belief made him difficult. One early collaborator described him as a "little fascist"; another deplored his manner of treating colleagues as servants. Frustrated by resistance from palaeontologists to his asteroid theory, he dismissed them as stamp-collectors rather than real scientists. His dedication to work strained his relationship with his first wife, Geraldine. A university instructor who encouraged students to secretly interfere with each other's experimental set-ups instilled in him a rigorous habit of vetting his own reasoning.
Anything is possible, unless it's not.