McAllister Hull (September 1, 1923 – February 9, 2011) was an American theoretical physicist who took part in the creation of the atomic bomb that was dropped over Nagasaki in 1945, ending World War II.
Early years
Hull was born on September 1, 1923, in Birmingham, Alabama. In his memoir, he describes how, in his boyhood, he read Isaac Asimov, Robert Heinlein, and other science-fiction writers, and discovered physics and Albert Einstein while doing school projects.
In a 2004 letter to the New York Review of Books, Hull wrote that his father had "tried to enlist" in General John J. Pershing's expedition to bring Pancho Villa to justice, "but needed his mother’s permission, which was not given. In 1917, he did enlist, and went to France with Pershing in the 4th Alabama, where he was in combat until wounded at Soissons, and in hospital service until 1919."
In the autumn of 1941, Hull entered Mississippi State University to study physics. After his freshman year, according to a 2007 newspaper profile, "he quit school and became a draftsman for an ordnance plant, where he was trained to test explosives to see if they were pure enough to be used for shells."
The Army and Los Alamos
In 1943 Hull was drafted into the Army Specialized Training Program, which identified enlisted personnel who had technical skills or some science education. He was assigned to the Special Engineer Detachment (SED) at Oak Ridge, Tennessee.
In the autumn of 1944, Hull and three other men were ordered to take a train from Oak Ridge to Lamy, New Mexico, where Hull dialed a number he had been told to call. A bus showed up and took Hull and his companions to Los Alamos. "I never saw those men again," Hull later recalled. Although he had only a high-school diploma, he had been identified as promising student of physics. He was put to work developing methods for, and overseeing, the casting of explosive lenses which would compress a plutonium core, resulting in an implosion. Hull, a sergeant, acted as foreman, supervising the team of civilians who worked on the casting.
During the months when he worked on the project to create Fat Man, the atomic bomb that would be dropped over Nagasaki, he was not told explicitly that he was working on a bomb. "But I knew enough physics to figure out what was going on." His work, which lasted until the summer of 1945, was considered so dangerous that the lab where he worked with his team was 15 miles from the other scientists' labs.
In order to cast the explosives, according to the New York Times, Hull used candy kettles and malted-milk stirrers. "We actually used a candy kettle ... to melt the explosives and then poured them into the mold to make the lenses," Hull told MSNBC in an interview. An article in the Bulletin of the Atomic Scientists tells the story this way: "One of Hull's early assignments was to figure our how to eliminate air bubbles in the explosive lenses. Remembering his experience making milk shakes as a waiter at college, he devised a stirrer that could be drawn up through the molten mixture, effectively bringing the bubbles to the surface."
In 1995, on the 50th anniversary of the atom bomb, Hull told CBS: "We were pouring two--two-speed explosives: a slow explosive called baritar, which was barium nitrate and TNT, mainly, and then a faster explosive called Comp-B, which had TNT in it and the rest of it either classified or I don't remember. It was--it was fast." Asked by a CBS reporter whether there had been "white coats" or a "lab atmosphere," Hull replied: "Oh, Lord, no."
Hull later recalled "the day that J. Robert Oppenheimer, the director of Los Alamos, brought Gen. Leslie Groves out to the lab. While looking at the mold for the lens, Groves accidentally stepped on and disconnected a hot water line. A stream of extremely hot water came out of the socket behind him, hitting him squarely in the rear. Hull succeeded – just barely – in stifling his laughter, but only until Oppenheimer turned to him and remarked that the incident "just goes to show you the incompressibility of water." There was no way Hull could contain himself after that. (Hull was relieved that Groves did not recognize him at the Trinity test several months later.)"
Hull was still at work on Fat Man At 5:30 A.M. on July 16, 1945, the test bomb produced by the project was detonated on the Alamogordo Bombing Range south of Los Alamos. "I was invited to go to a viewing site 20 miles away to watch," Hull later said. "It was pitch dark, and then suddenly, this brilliant light flashed, but since we were 20 miles away, we heard no sound," says Hull.