Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist. He shared the 1965 Nobel Prize in Physics with Julian Schwinger and Shin'ichirō Tomonaga "for their fundamental work in quantum electrodynamics (QED), with deep-ploughing consequences for the physics of elementary particles". He is also known for his work in the path integral formulation of quantum mechanics, the theory of the physics of the superfluidity of supercooled liquid helium, and the parton model. Feynman developed a pictorial representation scheme for the mathematical expressions describing the behavior of subatomic particles, which later became known as Feynman diagrams and remains widely used. He assisted in the development of the atomic bomb during World War II and became known to the wider public in the 1980s as a member of the Rogers Commission, the panel that investigated the Space Shuttle Challenger disaster. Along with his work in theoretical physics, Feynman has been credited with having pioneered the field of quantum computing and introducing the concept of nanotechnology. He held the Richard C. Tolman professorship in theoretical physics at the California Institute of Technology. In a 1999 poll of 130 leading physicists worldwide by the British journal Physics World, he was ranked the seventh-greatest physicist of all time. Feynman was a keen physics popularizer through books and lectures, including a talk on top-down nanotechnology, "There's Plenty of Room at the Bottom" (1959) and his undergraduate lectures, The Feynman Lectures on Physics (1961–1964). He delivered lectures for lay audiences, recorded in The Character of Physical Law (1965) and QED: The Strange Theory of Light and Matter (1985). Feynman also became known through Ralph Leighton's collections of his anecdotes, Surely You're Joking, Mr. Feynman! (1985) and What Do You Care What Other People Think? (1988). Leighton covered his dream of travelling to Tannu Tuva in Tuva or Bust!. He has been the subject of several biographies, starting with Genius: The Life and Science of Richard Feynman by James Gleick.