"Concern for man himself must always constitute
the chief objective of all technological effort -- concern for the big, unsolved problems of how
to organize human work and the distribution of commodities in such a manner as to assure that the
results of our scientific thinking may be a blessing to mankind, and not a curse."
Scientists in the 1930s, using machines that could break apart the nuclear cores
of atoms, confirmed Einstein's formula E=mc2 . The release of energy
in a nuclear transformation was so great that it could cause a detectable change
in the mass of the nucleus. But the study of nuclei -- in those years the fastest
growing area of physics -- had scant effect on Einstein. Nuclear physicists
were gathering into ever-larger teams of scientists and technicians, heavily
funded by governments and foundations, engaged in experiments using massive
devices. Such work was alien to Einstein's habit of abstract thought, done alone
or with a mathematical assistant. In return, experimental nuclear physicists
in the 1930s had little need for Einstein's theories.
In August 1939 nuclear physicists came to Einstein, not for scientific but for
political help. The fission of the uranium nucleus had recently been discovered.
A long-time friend, Leo Szilard, and other physicists realized that uranium
might be used for enormously devastating bombs. They had reason to fear that
Nazi Germany might construct such weapons. Einstein, reacting to the danger
from Hitler's aggression, had already abandoned his strict pacifism. He now
signed a letter that was delivered to the American president, Franklin.D. Roosevelt,
warning him to take action. This letter, and a second Einstein-Szilard letter
of March 1940, joined efforts by other scientists to prod the United States
government into preparing for nuclear warfare. Einstein played no other role
in the nuclear bomb project, but during the war he performed useful service
as a consultant for the United States Navy's Bureau of Ordnance.