The government committee created after World War II
to replace the Manhattan Project. The Atomic Energy Commission was charged
with overseeing all atomic research and development in the United
States. Oppenheimer was chairman of its General Advisory Committee
for several years. The Commission later turned against him, voting
to strip him of his security clearance.
The building block of all matter. An atom is the smallest
piece of an element that still retains all the characters of that
element, and all matter is made up of atoms. An atom is made up
of three main types of particles: protons (positively charged particles), electrons
(negatively charged particles), and neutrons (neutrally charged
particles). According to the atomic model created in the early twentieth
century, the protons and neutrons are located in the center, or
nucleus, of the atom, while the electrons orbit around the nucleus
on a series of energy levels. The concept of an atom had existed
for thousands of years, but it wasn't until the twentieth century
that physicists were able to prove its existence and gain some understanding
of its internal structure.
The name given to the state of continuing hostility
between the United States and the Soviet Union after World War II.
For four decades, American foreign policy was dictated by the necessities of
the Cold War, as the United States strategized about how best to
defeat the Soviet Union without antagonizing it into full-fledged
war. The Cold War came to a symbolic end in 1989, with the tearing
down of the Berlin Wall–the divider between democratic West Germany
and communist East Germany. The non-war came to a definitive end
two years later when, in 1991, the Soviet Union dissolved into independent
The philosophy created by Karl Marx to describe a society
in which all property is owned by the community rather than individuals.
After the communists came to power in the Russian Revolution of
1917, communism became synonymous with Russia and the Soviet Union.
In the period before World War II, communism was considered a socially
acceptable liberal philosophy. But with the advent of the Cold War,
communism was determined to be an evil force–and all Americans with
any connections to communism were feared to be enemy agents of the
One of the two bombs designed at Los Alamos. It used
a sphere of plutonium as its radioactive core. The bomb mechanism
used what was called the "implosion method": The plutonium was surrounded
by explosives, and when the explosives fired, they set off a shock
wave that compressed the plutonium into a critical mass, setting
off a nuclear explosion. This is the type of bomb that was used
at both Trinity and Nagasaki.
The Japanese city that was bombed by the United States
on August 6, 1945. One hundred thousand of its 300,000 residents were
killed instantly, and another 100,000 would die over the next five
years. Three days later, the United States dropped a second bomb
over the Japanese city of Nagasaki. Five days after that, Japan
Also known as the "Super," this bomb was developed
after World War II and was one thousand times as powerful as the atomic
bomb. It is called a hydrogen bomb because its energy comes from
the fusion, or combining, of hydrogen atoms. Fusion is the same
process that powers the sun.
The code-name given to the atomic bomb development
program during World War II. The Manhattan Project consisted of
several laboratories in secret locations across the country, including
the University of Chicago, Tennessee, and Los Alamos, New Mexico.
Over the course of three years, the government spent over two billion
dollars in pursuit of the world's first atomic bomb. Although almost
every top physicist in the country was involved, the government
managed to keep the program a secret from the rest of the world.
One of the two bombs designed at Los Alamos. It utilized
two masses of Uranium 235 as its radioactive material. The bomb mechanism
used what was called the "gun-assembly method": One subcritical
mass of uranium was fired at another, and they combined to make
a critical mass, setting off a nuclear explosion. This is the type
of bomb that was dropped on Hiroshima.
The secret lab where some of the best physicists in
the world assembled to design and construct the world's first atomic
bomb. The scientists lived on the isolated New Mexico compound for three
years–and residents of neighboring towns never found out what went
on there. Oppenheimer was the director of the lab. Thanks to his
position there, the public later saw him as the man responsible
for creating the bomb.
The term describing the anti-communist hysteria that
swept through Washington in the 1950s, spearheaded by the conservative
senator Joseph McCarthy. McCarthy and his allies devoted themselves
to rooting out communist spies from every walk of American life–their
zeal often leading them to destroy people's lives with little or
no evidence to back up their claims.
The process by which the nucleus of an atom splits
in half, releasing an enormous amount of energy. When a nucleus fissions,
it also releases neutrons, which can then go on to impact and split
other nuclei, creating a chain reaction. The fission of a nucleus
is the process at the core of an atomic bomb. A critical mass of
radioactive material is the amount required to start a chain reaction.
The new system of physics created at the beginning
of the twentieth century to explain the bizarre, counterintuitive behavior
of light and subatomic particles. Physicists realized that activity
on this small scale could not be described using physical models
from the larger world, and they were forced to cobble together a
new understanding of the way the basic particles of matter interact.
The creation of quantum physics constituted an exciting revolution
in the way people studied and applied physics, a revolution that
was totally dominated by European figures such as Niels Bohr, Wolfgang
Pauli, and Werner Heisenberg. The American physics community took
a back seat, struggling to keep up with the newest discoveries of
the European colleagues.
The desolate site of the world's first atomic explosion.
In a single moment, it represented the triumph of the past three
years and the nuclear horrors that were to follow.
University of Göttingen
The center of the quantum physics revolution. Oppenheimer
did his graduate work there in physics, studying under some of the most
famous names in physics.