Leonard Emanuel Parker (born Leonard Pearlman in 1938 in Brooklyn, New York) is a Distinguished Professor Emeritus of Physics and a former Director of the Center for Gravitation and Cosmology at the University of Wisconsin–Milwaukee. During the late 1960s, Parker established a new area of physics - quantum field theory in curved spacetime. Specifically, by applying the technique of Bogoliubov transformations to quantum field theory with a changing gravitational field, he discovered the physical mechanism now known as gravitational particle production. His work inspired research by hundreds of physicists and has been cited in more than 2,000 research papers; it was credited in the memoirs of Soviet physicist Andrei Sakharov and helped Stephen Hawking discover the creation of particles by black holes.
Recently, with David Toms of Newcastle University, Parker co-wrote a latest addition to graduate-level textbooks on quantum field theory in curved spacetime, entitled Quantum Field Theory in Curved Spacetime: Quantized Fields and Gravity (Cambridge University Press, 2009, ISBN ).
He received his PhD from Harvard University in 1967. His advisor was Sidney Coleman.