American physicist stubs

Hartland Sweet Snyder (1913, Salt Lake City – 1962) was an American physicist who, together with Robert Oppenheimer, showed how large stars would collapse to form black holes. This work modeled the gravitational collapse of a pressure-free homogeneous fluid sphere and found that it would be unable to communicate with the rest of the universe.
This discovery was depicted in the movie Oppenheimer, where Snyder was portrayed by actor Rory Keane.Historian of physics David C. Cassidy assessed that this prediction of black holes might have won a Nobel Prize in Physics had the authors been alive in the 1990s when evidence was available.Some publications Snyder authored together with Ernest Courant laid the foundations for the field of accelerator physics. In particular, Snyder with Courant and Milton Stanley Livingston developed the principle of strong focusing that made modern particle accelerators possible. The Courant–Snyder parameters, a method of characterizing the distribution of particles in a beam, were an important part of that contribution.In 1954, Snyder bet against Maurice Goldhaber that antiprotons existed, and won.

Leon Knopoff (July 1, 1925 – January 20, 2011) was an American geophysicist and musicologist. He received his education at Caltech, graduating in 1949 with a PhD in physics, and came to UCLA the following year. He served on the UCLA faculty for 60 years. His research interests spanned a wide variety of fields and included the physics and statistics of earthquakes, earthquake prediction, the interior structure of the Earth, plate tectonics, pattern recognition, non-linear earthquake dynamics and several other areas of solid Earth geophysics. He also made contributions to the fields of musical perception and archaeology.

Leonard Emanuel Parker (born Leonard Pearlman; in 1938) 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 cosmological particle production. His breakthrough discovery has a surprising consequence: the expansion of the universe can create particles out of the vacuum.
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.Along 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 978-0-521-87787-9).
He received his PhD from Harvard University in 1967. His advisor was Sidney Coleman.

Joseph Harold Rush (April 17, 1911 – September 12, 2006) was a physicist, parapsychologist and author. He was the first secretary-treasurer of the Federation of American Scientists, and published numerous articles and two textbooks.
Rush was born in Mt. Calm, Texas. In the 1930s his employment as a radio operator in the Dallas Police Department became a way to support his family during the Great Depression. After earning a master's degree in physics, he taught at Texas Technical College in Lubbock and at Denison University. In 1944 he joined the Manhattan Project at the Clinton Engineer Works in Oak Ridge, Tennessee. After the end of the war, he became secretary-treasurer of the Federation of American Scientists, working in Washington to secure civilian control of nuclear power.
Rush received his PhD in physics from Duke University in 1950, and moved to Boulder, Colorado, to work at the High Altitude Observatory of the University of Colorado. He joined the National Center for Atmospheric Research upon its inception, and retired in 1974.
Over his lifetime, Rush authored many articles and books, including The Dawn of Life, a book examining the origins of life on Earth, and Foundations of Parapsychology: Exploring the Boundaries of Human Capability, a textbook on parapsychology.