Joseph Rotblat — Polish Physicist born on November 04, 1908, died on August 31, 2005

Sir Joseph Rotblat KCMG CBE FRS was a Polish physicist, a self-described "Pole with a British passport". Rotblat was the only physicist to leave the Manhattan Project on the grounds of conscience. Rotblat's work on nuclear fallout was a major contribution toward the ratification of the 1963 Partial Nuclear Test Ban Treaty. A signatory of the Russell–Einstein Manifesto, he was secretary-general of the Pugwash Conferences on Science and World Affairs from their founding until 1973. He shared, with the Pugwash Conferences, the 1995 Nobel Peace Prize for efforts toward nuclear disarmament... (wikipedia)

The decision to use the atom bomb on Japanese cities, and the consequent buildup of enormous nuclear arsenals, was made by governments, on the basis of political and military perceptions.
I have to bring to your notice a terrifying reality: with the development of nuclear weapons Man has acquired, for the first time in history, the technical means to destroy the whole of civilization in a single act.
At a time when science plays such a powerful role in the life of society, when the destiny of the whole of mankind may hinge on the results of scientific research, it is incumbent on all scientists to be fully conscious of that role, and conduct themselves accordingly.
There is no direct evidence that nuclear weapons prevented a world war. Conversely, it is known that they nearly caused one.
I appeal to my fellow scientists to remember their responsibility to humanity.