John Alexander Simpson (November 3, 1916 – August 31, 2000) was an American physicist and science educator. He was deeply committed to educating the public and political leaders about science and its implications, most notably as a principal founder of the Bulletin of the Atomic Scientists and a long-time member of the organizations Board of Sponsors. He is known for inventions such as the gas flow α-particle proportional counter (for measuring plutonium yields in the presence of high intensity fission products), and the neutron monitor, and for having several of the instruments he created launched into space, such a dust flux monitor aboard the Stardust spacecraft. Simpson spent his career as an instructor and researcher for the University of Chicago's Enrico Fermi Institute and Department of Physics, where he conducted experiments in nuclear physics and with cosmic rays. His research continued up until a few weeks prior to his death. He died of pneumonia which he contracted in the hospital following a successful heart surgery. The year he died, his instruments in space had been sending data back for nearly 40 years. Early life Born in Portland, Oregon, Simpson was an accomplished clarinetist and saxophonist in his early years, receiving an award in high school for his virtuosity. He received an AB degree from Reed College in 1940, where he became interested in the history of science and technology from the Greeks to the Middle Ages to the most recent discoveries in astronomy and physics. He obtained an MS from New York University in 1943, and a Ph.D a year later. It was at New York University in 1943 when Simpson was invited to be employed at University of Chicago. Volney Wilson, an administrator at the university's Metallurgical Laboratory asked him to help invent instruments for measuring high levels of radioactivity. It took much convincing, but Simpson finally agreed to help. Research Simpson began his professional career as a physicist in 1943 where he acted as a group leader on the Manhattan Project. The Manhattan Project was the codename for a United States project with the United Kingdom and Canada conducted during World War II to develop the first atomic bombs. It was common for governments to recruit physicists during World War II for such tasks. Simpson had taken up the offer after recognizing the social and human implications of nuclear energy and wanted to partake in its development. Because