Qian Xuesen was a Chinese rocket scientist who graduated from MIT and Caltech, a major contributor to the field of engineering and aerodynamics, worked on the Manhattan Project, was deported by the US during the Red Scare to China, and became the "Father of Chinese Rocketry." -u/Krelius

Back in 1945, a physicist at Kodak in Rochester discovered the secret Manhattan project atomic testing 2000 miles away in New Mexico due to straw containing traces of Cerium-141. The straw was sourced from milling plants in Indiana and Iowa that was used to make the film packaging. -u/arkster

In 1944 a Sci-fi writer wrote a short story describing nuclear bombs and their construction methods called "Deadline". It was so accurate that the Counter intelligence Corps feared a leak or spy on the Manhattan Project. In actuality, the info was always there in public scientific journals. -u/richard-mt

Theodore Hall was among the youngest Manhattan Project scientists. He finished high school at 14, graduated from Harvard at 18, and recruited for the nuclear program at 19. Fifty years later, near death, he admitted to having been a Soviet informant the entire time. -u/stratohornet

The B-29 Superfortress, the planes that dropped the atomic bombs, cost $3B to develop. The entire Manhattan Project was $1.9B in development. Making the planes about 50% more expensive than the bombs themselves. -u/xE1NSTE1Nx2049

Sir James Chadwick, the English physicist who discovered the neutron and was awarded the Nobel Prize in 1935, actually enrolled in Physics by mistake when he was a University student. He wanted to study maths. He also led the British team of the Manhattan project. -u/Bara_Chat

Details of the Manhattan Project were so secret that many workers had no idea why they did their jobs. A laundrywoman had a dedicated duty to "hold up an instrument and listen for a clicking noise" without knowing why. It was a Geiger counter testing the radiation levels of uniforms. -u/derstherower

As US senator, Truman took note of a project receiving funding named “Expediting Production” with no further explanation. He asked the Secretary of War about it who said it was classified. Truman learned about The Manhattan Project when he became president from the same Secretary of War. -u/Mad_Chemist_

A Belgian businessman was instrumental to the Manhattan Project's success. Realizing uranium's importance, he shipped 1,200 tons of it to Staten Island. When Lieutenant Colonel Nichols contacted him, he simply responded: "You can have the ore now. It is in New York. I was waiting for your visit." -u/plopsaland

In addition to Little Boy and Fat Man, the Manhattan project also worked on a design called "Thin Man". The project was shelved after it was found that plutonium isotope impurities would have likely caused it to blow itself apart prematurely. -u/Dovahkiin1337

When Truman told Stalin about the Manhattan project in July of 1945, Stalin displayed little reaction, since Stalin had known about the project for almost 4 years before Truman, and he arguably knew more about it than Truman himself did. -u/MegaZeroX7

In 1945, the director of the Los Alamos Lab during the Manhattan Project, Robert Oppenheimer, bet ten dollars against a colleague's entire month's pay that the bomb would not work at all. The actual result was 21 kilotons, more than 4 times as much as had been predicted by most at Los Alamos. -u/LateBoomerKY

More than a dozen vulnerable people were involuntarily injected with plutonium as part of the Manhattan Project, in order to learn the human biological reaction to radiation poisoning. -u/aerostotle

Leona Woods was the only woman physicist on the team which built the world's first nuclear reactor as part of the Manhattan Project. She became a mother during the Project but hid her pregnancy as not to miss work. Afterward as a professor, she authored >200 papers in physics and astrophysics. -u/blueberrisorbet

Bohemian Grove is a restricted 2700-acre campground in California that is only available for the world's elite. It is described as a private vacation getaway yet it is famous for hosting the Manhattan Project planning meeting in 1942, that led to the creation of the atomic bomb. -u/SneakerMarket1

Prior to the first Nuclear Weapon test "Trinity", Manhattan Project scientists wanted to get an idea of how big a nuclear explosion might be.....so they did the only logical thing and stacked 100 tons of TNT at the test site and blew it up. -u/Spaceisveryhard

Manhattan Project nuclear physicist Alvin Weinberg was fired from his job for continually advocating for a safer and less weaponizable nuclear reactor using Thorium, one that has no chance of a meltdown. -u/jmepstein1

Nuclear physicists working on the Manhattan Project at Purdue University created the “barn unit” to secretly describe the approximate cross-sectional area presented by the typical nucleus, which, in particle physics, is a relatively large target to hit (i.e. the broad side of a barn). -u/751assets

US Presidential candidates get intelligence briefings. Harry Truman began this practice in 1952 as a reaction to his own experience at the beginning of his Presidency - he knew next to nothing about the U.S.’s intelligence apparatus, including the Manhattan Project. -deleted user

Harry Daghlian was a 24-year-old physicist with the Manhattan Project. He accidentally dropped a brick into the center of a plutonium core and exposed himself to a lethal dose of radiation, dying 25 days after the accident. -u/stemh18

Despite having some of the top physicists in the world, including Werner Heisenberg, Nazi Germany was unable to build a nuclear weapon partly because they did not want to affiliate with "Jewish Physics" causing many scientists to defect to the US to help with the Manhattan Project. -u/Narwall776

Only 12 individuals, out of a total of 150,000 scientists and engineers who worked on the Manhattan project, were familiar with the overall project. -u/berlioz1982

In 1944, Lex Luthor was the first character in a comic book (and one of the first in fiction) to use an atomic bomb. The United States Department of War asked this story line be delayed from publication, which it was until 1946, to protect the secrecy of the Manhattan Project. -u/ExoSpectra

Richard Feynman, a physicist who worked on the Manhattan Project, was hounded by the FBI until he sent them a memo to leave him alone as he’d helped build the atomic bomb. When J. Edgar Hoover found out about it, he also sent out a memo telling them not to pursue Feynman unless told otherwise. -deleted user

Manhattan Project mathematician Richard Hamming was asked to check some arithmetic by a fellow researcher. Hamming planned to give it to a subordinate until he realized it was a set of calculations to see if the nuclear detonation would ignite the entire Earth's atmosphere. -u/torgis30