Born on a cattle ranch near Merriman, Nebraska, Fitch was drafted into the U.S. Army during World War II, and worked on the Manhattan Project at the Los Alamos Laboratory in New Mexico. He later graduated from McGill University, and completed his Ph.D. in physics in 1954 at Columbia University. He was a member of the faculty at Princeton University from 1954 until his retirement in 2005.
Val Logsdon Fitch was born on a cattle ranch near Merriman, Nebraska, on March 10, 1923, the youngest of three children of Fred Fitch, a cattle rancher, and his wife Frances née Logsdon, a school teacher. He had an older brother and sister. The family farm was about 4 square miles (10 km2) in size, and was about 40 miles (64 km) from the site of the Wounded Knee Massacre. The ranch was a small one; his father specialized in raising breeding stock. Soon after his birth, his father was badly injured in a horse riding accident and could no longer work on his ranch, so the family moved to the nearby town of Gordon, Nebraska, where his father entered the insurance business. It was here that he attended school, graduating from Gordon High School in 1940 as valedictorian.
Fitch attended Chadron State College for three years, then transferred to Northwestern University; but this was during World War II, and his studies were interrupted by being drafted into the U.S. Army in 1943. After he had completed basic training, the Army sent him to Carnegie Institute of Technology for training under the Army Specialized Training Program. Under this program, some 200,000 soldiers attended colleges for intensive courses. Fitch was in the program for less than a year before the manpower requirements of the war became too great, and the Army terminated the program. Most of the soldiers in the ASTP were posted to combat units, but Fitch was one of a hundred or so ASTP soldiers who joined the Special Engineer Detachment (SED), which provided much-needed technicians to the Manhattan Project.
The Army sent Fitch to the Manhattan Project's Los Alamos Laboratory in New Mexico. By mid-1944, about a third of the technicians at Los Alamos were from the SED. While there, he met many of the greats of physics including Niels Bohr, James Chadwick, Enrico Fermi, Isidor Isaac Rabi, Bruno Rossi, Emilio Segrè, Edward Teller and Richard C. Tolman, in some cases attending courses on physics taught by them. He worked in the group headed by Ernest Titterton, a member of the British Mission, and became well-acquainted with the techniques of experimental physics. He participated in the drop testing of mock atomic bombs that was conducted at Wendover Army Air Field and the Salton Sea Naval Auxiliary Air Station, and worked at the Trinity site, where he witnessed the Trinity nuclear test on July 16, 1945. He was discharged from the Army in 1946, but continued to work at Los Alamos as a civilian for another year in order to earn some money. He would briefly return to Los Alamos in summer 1948.
His wartime experiences led Fitch to decide to become a physicist. Robert Bacher, the head of the physics division at Los Alamos, offered him a graduate assistantship at Cornell University, but first he needed to complete his undergraduate degree. Rather than return to Northwestern or Carnegie Mellon, he elected to enter McGill University, which Titterton had recommended. Fitch graduated from McGill with a bachelor's degree in electrical engineering in 1948. On the advice of Jerry Kellogg, who had been a student of Rabi's at Columbia University, and was a division head at the Los Alamos, Fitch decided to pursue his doctoral studies at Columbia. Kellogg wrote him a letter of introduction to Rabi. James Rainwater became his academic supervisor. Rainwater gave him a paper by John Wheeler concerning mu-mesic atoms, atoms in which an electron is replaced by a muon. These had never been observed; they were completely theoretical and there was no evidence that they existed, but it made a good thesis topic.