Kenneth Tompkins Bainbridge (July 27, 1904 – July 14, 1996) was an American physicist at Harvard University who did work on cyclotron research. His precise measurements of mass differences between nuclear isotopes allowed him to confirm Albert Einstein's mass–energy equivalence concept. He was the Director of the Manhattan Project's Trinity nuclear test, which took place July 16, 1945. Bainbridge described the Trinity explosion as a "foul and awesome display". He remarked to J. Robert Oppenheimer immediately after the test, "Now we are all sons of bitches." This marked the beginning of his dedication to ending the testing of nuclear weapons and to efforts to maintain civilian control of future developments in that field. Early life Kenneth Tompkins Bainbridge was born in Cooperstown, New York. He was educated at Horace Mann School in New York. While at high school he developed an interest in ham radio which inspired him to enter Massachusetts Institute of Technology (MIT) in 1921 to study electrical engineering. In five years he earned both Bachelor of Science (S.B.) and Master of Science (S.M.) degrees. During the summer breaks he worked at General Electric's laboratories in Lynn, Massachusetts and Schenectady, New York. While there he obtained three patents related to photoelectric tubes. Normally this would have been a promising start to a career at General Electric, but it made Bainbridge aware of how interested he was in physics. Upon graduating from MIT in 1926, he enrolled at Princeton University, where Karl T. Compton, a consultant to General Electric, was on the faculty. In 1929, he was awarded a Ph.D. in his new field, writing his thesis on "A search for element 87 by analysis of positive rays" under the supervision of Henry DeWolf Smyth. Early career Bainbridge enjoyed a series of prestigious fellowships after graduation. He was awarded a National Research Council, and then a Bartol Research Foundation fellowship. At the time the Franklin Institute's Bartol Research Foundation was located on the Swarthmore College campus in Pennsylvania, and was directed by W. F. G. Swann, an English physicist with an interest in nuclear physics. Bainbridge married Margaret ("Peg") Pitkin, a member of the Swarthmore teaching faculty, in September 1931. They had a son, Martin Keeler, and two daughters, Joan and Margaret Tomkins. In 1932, Bainbridge developed a mass spectrometer with a resolving power of 600 and a relative precision of one part in 10,000. He used this instrument