The Manhattan Project is the name of the program that developed the
atomic bomb in the 1940s. The United States dropped two atomic
bombs on Japan in 1945 to end World War II (1939–45). Ever since
then, the world has wrestled with the problem of how to prevent a
nuclear war.
Nuclear potential
The atomic bomb is a military weapon based on the science of splitting
the nuclei within certain elements. (The nucleus is the center of an atom,
the smallest part of a chemical element.) The splitting process is called
nuclear fission, and the elements that are used in the process are uranium
and plutonium.
Nuclear fission was discovered by scientists in Germany in late 1938.
Physicists throughout the world quickly recognized the possibility of
using the enormous energy released in this reaction to build weapons.
There were, however, many questions to answer about the new science
and challenges to overcome before a bomb could be built.
Both Germany and England investigated the possibility of a nuclear
weapon early in World War II, but the war quickly demanded their full
attention. Only the United States had sufficient resources and the scientific manpower to undertake the project at the time.
The development of a nuclear weapon
The United States was fearful that Germany, led by Nazi dictator Adolf
Hitler (1889–1945), might develop an atomic bomb. President
Franklin D. Roosevelt (1882–1945; served 1933–45) initiated secret research to produce the first weapon. The project became known as the
Manhattan Project.
In 1939, funding was increased to allow theoretical and experimental research to move more quickly. In 1942, the Office of Scientific
Research and Development began overseeing feasibility studies in laboratories. By mid-1942, it was obvious that new factories would have to
be built. Congress approved a special fund for the president to use for
secret projects, and in December 1942 Roosevelt approved $400 million
for the project. By the end of the war, funding for the project totaled an
enormous and unforeseen $2 billion.
With such immense funding and pressure to produce a weapon to
use during the war, General Leslie Groves (1896–1970), who was in
charge of the project, initiated research in as many areas as possible at the
same time. No approach was to be disregarded until proven unsatisfactory. In December 1942, physicist Enrico Fermi (1901–1954) succeeded
in producing and controlling a chain reaction of fission in a reactor built
at the University of Chicago.
To support further research, top-secret plants were constructed. A
plutonium-generating reactor was built in Hanford, Washington. A gasdiffusion facility was built in Oak Ridge, Tennessee, and a physics
research lab was constructed in Los Alamos, New Mexico.
Scientists at Los Alamos worked to overcome the technical problem
of how to amass fissionable material and shape it into a bomb. Uranium
and a newly created element, plutonium, were at the center of the
research. Eventually, two types of bombs were developed at Los Alamos.
The first bomb was tested successfully in a southern New Mexican desert
at Alamogordo on July 16, 1945. The explosion shook the earth with the
power of twenty thousand tons of dynamite, and it was the beginning of
the atomic age.
The end of World War II
By summer 1945, Germany and Italy had surrendered to the United
States and its Allies. Japan, however, was not willing to surrender, despite
aggressive attacks from the United States. President Harry S. Truman
(1884–1972; served 1945–53), after issuing several warnings and
demands for surrender, gave orders to use the atomic bomb as a military weapon.
On August 6, 1945, the bomber Enola Gay dropped a uranium
bomb on Hiroshima, Japan. It totally destroyed four square miles of the
city and killed more than fifty thousand people. Then on August 9,
1945, a bomber approached Japan. This time it headed for the city of
Nagasaki and dropped a plutonium bomb. It destroyed one-third of the
city and killed more than forty thousand people. The Japanese surrendered days later.