The United States and Soviet Union
Two weeks into his presidency, Truman is thrown into the Manhattan Project, where the atomic bomb is being secretly created.
The secret, three-day, super conference in New Mexico works on developing the hydrogen bomb.
Truman signs this act, which in turn establishes the Atomic Energy Commission.
The US detonated a 17-megaton hydrogen bomb, "Bravo", in the Pacific Ocean, contaminating a Japanese fishing boat, Lucky dragon.
In Geneva, the first United Nations conference begins on the peaceful use of atomic energy.
A team of Soviet Scientists begin the assembly of the first full-scale nuclear reactor.
Exploded in Kazakhstan
The Soviet Union conducts its second nuclear test, an improved plutonium bomb.
The Soviet Union's leader dies.
The Soviet Union unexpectedly accepts the United Nations proposal.
United State's Vanguard 1-NRL
Vanguard 2-NASA (NRL)1
Soviet Union's Sputnik 1
Dog Laika on the Sputnik 2