A-bomb anniversary.

AUGUST 6, 1945--The world's first atomic weapon drops from a U.S. warplane, killing 100,000 people instantly and destroying the city of Hiroshima, Japan. Three days later, another atom bomb reduces Nagasaki, Japan, to rubble.

These two blasts--each thousands of times more powerful than last spring's Oklahoma City explosion--thrust the world into the "nuclear age." Scientists had learned how to unleash the energy that holds together the nuclei, or centers, of atoms--tiny building blocks of matter.

"We knew the world would not be the same," said physicist J. Robert Oppenheimer, who led the effort to design the bombs.

Following the Japanese surrender--which ended World War II on August 14, 1945--many of the scientists who built the first nuclear bombs turned to research on peaceful uses of nuclear energy, such as generating electricity. "[Nuclear power] could solve the problem of [supplying] adequate energy for future generations," chemist Glenn Seaborg wrote to President Kennedy in 1962.

But others worried about what would happen with nuclear knowledge in the hands of potential enemies. Beginning in the late 1940s, the U.S. and the Soviet Union--opponents in many global conflicts--entered an "arms race." They designed and built huge stockpiles of nuclear weapons. The most powerful had 5,000 times the blast power of the Hiroshima bomb. In the 1950s and 60s, China, France, and Great Britain also began building nuclear weapons.

But as the number of atomic weapons grew (see graph, below), nations began to discuss other ways to deal with the "nuclear threat." In 1968, leaders from many nations signed a treaty to prevent the spread of nuclear weapons beyond the five nations that already had them.

[ILLUSTRATION OMITTED]

Just last May, 174 nations extended that treaty indefinitely. According to the treaty, the U.S. and former Soviet Union must "pursue negotiations in good faith" to stop the arms race and completely dismantle all nuclear weapons.

"Making the treaty permanent opens a new and more hopeful chapter in our history, a time when all nations will be more secure," said President Clinton after the treaty was renewed.

Still, several nations that have the technology to build nuclear weapons (see SW 2/24/95, p. 5) have refused to sign the treaty.

Do you think it will ever be possible to eliminate all nuclear weapons from the world? Do you think any of these weapons will ever be used in war again? Why or why not?