262 J. ROBERT OPPENHEIMER
I
n 1938, the world stood at the
threshold of the atomic age.
One man would step forward
to lead the scientific drive that
would usher in this new era. For J.
Robert Oppenheimer, this decision
would ultimately destroy him. He
was the administrator of the largest
scientific project the world had
seen—the Manhattan Project—but
came to deeply regret his part in it.
Drive to the center
Oppenheimer’s varied professional
life had been characterized by a
ruthless drive to “be where it’s at”
and this compulsion took the newly
graduated Harvard man to Europe,
the center of a blossoming of
theoretical physics. At Göttingen
University, Germany, in 1926, he
produced the Born–Oppenheimer
approximation with Max Born,
used to explain, as Oppenheimer
put it, “why molecules are
molecules.” This method extended
quantum mechanics beyond single
atoms to describe the energy of
chemical compounds. It was an
ambitious mathematical exercise
as a dizzying range of possibilities
for each electron in a molelcule hadIN CONTEXT
BRANCH
PhysicsBEFORE
1905 Albert Einstein’s famous
mass-energy equivalence
equation E = mc^2 describes
how tiny masses “store” large
amounts of energy.1932 John Cockcroft and
Ernest Walton’s experiments
splitting lithium nuclei
with protons hint at the
enormous energy locked
inside the nucleus.1939 Leó Szilárd spots that
a single fission event of
uranium-235 releases three
neutrons and suggests that
a chain reaction is possible.AFTER
1954 The USSR’s Obninsk
Nuclear Power Plant goes into
operation. It is the first nuclear
power station to generate
electricity for a country’s
national grid.to be computed. Oppenheimer’s
work in Germany has proved
crucial to calculating energy in
modern chemistry, but the final
breakthrough that would lead to
the atomic bomb came after he
had returned to the US.Fission and black holes
The chain reaction that led to the
building of the atomic bomb began
in mid-December 1938, when
German chemists Otto Hahn and
Fritz Strassmann “split the atom”
in their Berlin laboratory. They had
been firing neutrons at uranium,Splitting the nucleus of an atom of uranium
releases three neutrons. An awesome power is locked inside the
nucleus of an atom.The three released neutrons can cause the nuclei of up to three
more atoms to split, but if at least one splits, a
chain reaction can be initiated.The chain reaction
can be controlled by
absorbing neutrons
(nuclear fission reactor).The chain reaction can
be uncontrolled, releasing
enough energy to cause an
explosion (nuclear bomb).Each time a nucleus is split, a fraction of its mass is
turned into energy.