Leo Szilard• A Hungarian-American physicist who

worked on the Manhattan Project he was probably the first scientist to think seriously of building real atomic bombs. He fled his native country to accept an offer to conduct research at Columbia University in Manhattan. Nobel Laureate Enrico Fermi soon joined him there. Later, he moved to the University of Chicago to continue to work on developing the bomb. If anyone truly saw the bomb from start to finish, it was Szilard.

• He also was the co-holder, with Enrico Fermi, of the patent on the nuclear reactor.

Neils Bohr

• Danish physicist, developer of quantum theory.

• Gained a crucial insight into the principles of fission - that U-235 and U-238 must have different fission properties, that U-238 could be fissioned by fast neutrons but not slow ones, and that U-235 accounted for observed slow fission in uranium.

Enrico Fermi• Conducted the first nuclear

fission experiment at Columbia University, developed the first nuclear reactor, and demonstrations of the existence of new radioactive elements produced by neutron irradiation. Worked on the Chicago pile-1 of the Manhattan Project.

• Won the Nobel Prize in 1938.

Albert Einstein

• Physicist E=MC2, relativity in early 1900s.

• Co-authored, with Szilard, to President Roosevelt, which warned him of the possibilities of nuclear weapons, delivered in October 1939.

James Chadwick• British scientist who studied under Ernst

Rutherford.• In 1932, he proved the existence of neutrons -

elementary particles devoid of any electrical charge. Neutrons, since they are not electrically charged, need not overcome any electric barrier and are capable of penetrating and splitting the nuclei of even the heaviest elements. Paved the way towards the fission of uranium 235 and towards the creation of the atomic bomb.

• He was awarded the Nobel Prize for Physics in 1935.

Ernest O. Lawrence

• In 1929 he invented the cyclotron, a device for accelerating nuclear particles to very high velocities without the use of high voltages. He was involved with the Manhattan Project from nearly the beginning. He was in charge of the electromagnetic separation work at Oak Ridge, Tennessee.

• He won the Nobel Prize in Physics in 1939.

Robert Oppenheimer

• Founder of the American school for theoretical physics, Berkeley.

• Scientific director of the Manhattan Project, based in Los Alamos, New Mexico. “The Father of the Atomic Bomb.”

• After the war, he was chief advisor to the US Atomic Energy Commission to control the use of nuclear weapons.