But the nuclear powers still cling tenaciously to their weapons.

The present basic philosophy is nuclear deterrence.

The most terrifying moment in my life was October 1962, during the Cuban Missile Crisis. I did not know all the facts - we have learned only recently how close we were to war - but I knew enough to make me tremble.

We are told that the possession of nuclear weapons - in some cases even the testing of these weapons - is essential for national security. But this argument can be made by other countries as well.

Technology is driving us together. In many ways we are becoming like one family. With the global threats resulting from science and technology, the whole of humankind now needs protection. We have to extend our loyalty to the whole of the human race.

The chief task was to stop the arms race before it brought utter disaster. However, after the collapse of communism and the disintegration of the Soviet Union, any rationale for having nuclear weapons disappeared.

I saw science as being in harmony with humanity.