The history of the atomic bomb dates back to the early 1900's when Einstein's theory of relativity proved a basis for understanding nuclear energy and showed that the atom contained vast energy. This energy seemed beyond men's grasp until the late 1930's.
In 1939 scientists succeeded in splitting the atoms of uranium by bombarding them with neutrons. They found that the split atoms released neutrons and energy. Physicists found that the fission of these atoms could produce a chain reaction.
In the summer of 1939 Albert Einstein wrote a letter to President Roosevelt explaining the potential for atom-splitting devices in warfare as well as the possibility of other countries possessing this information. .
In the summer of 1940 Einstein moved to Manhattan, New York to begin research on an atomic bomb. The "Manhattan Project" as the atomic bomb project was called, tested their first prototype in the desert of Alamogordo, New Mexico, on July 6, 1945. Due to the success of these tests the U.S. military requested these bombs for use in World War 2. The first military application of the atomic bomb followed shortly after the tests. On August 6, 1945 the U.S. dropped its first atomic bomb on the city of Hiroshima. The blast covered approximately four and a half miles killing over 100,000 people. The second bomb was dropped on Nagasaki killing over 40,000 people. These weapons of mass destruction ended the war. .
Today the atomic bomb is known as a thing of the past since the last time it was employed by any country was the attack on Japan in 1945. Since then 130 countries have signed a peace treaty prohibiting the use of atomic bombs in warfare. This, however has not stopped countries from testing these and similar bombs such as the hydrogen bomb and the fusion bomb. These bombs use the same principals as the atomic bomb, but with a few variations.
The hydrogen bomb uses the fusion of atoms and hydrogen to produce great heat and activity.