With Iran in mind, some of the country's leading physicists, including several Nobel laureates, sent a letter to members of the U.S. Senate and House of Representatives last week urging measures to restrict the use of nuclear weapons by the United States.

The letter is signed by 22 physicists, including Cornell's Edwin Salpeter, the James Gilbert White Distinguished Professor of the Physical Sciences, Emeritus; and Kurt Gottfried, professor emeritus of physics and chairman of the Union of Concerned Scientists.

"As physicists, members of the profession that brought nuclear weapons into existence, we write to urge you to pass binding legislation to restrict the authority of the President to order nuclear strikes against non-nuclear-weapon states," the letter reads.

"In view of the rising tensions with Iran and the potential for military confrontation, as well as the public statement by President Bush on April 18, 2006, that a nuclear strike against Iran is an option 'on the table,' we believe it is essential that Congress address this issue at the earliest possible time. ... We are firmly convinced that Congress should have a say on which course of action would best serve the American people on the use of the terrible weapons our profession helped create.

"A decision that would have a major impact on the course of history and could ultimately threaten the survival of civilization should not be in the sole hands of the President unless absolutely unavoidable. We urge Congress to pass binding legislation to forbid the use of nuclear weapons by the United States against countries which do not possess nuclear weapons, except with explicit prior Congressional authorization for such action."

Salpeter, who was a postdoctoral researcher under the late Nobel laureate Hans Bethe, said the letter continues a tradition of activism practiced by his former mentor. "For Kurt [Gottfried] and me it's very much in the tradition of Hans Bethe," he said. As members of the profession that created the nuclear bomb, Salpeter said he and colleagues feel a particularly strong responsibility to warn against its use -- especially now, as rhetoric against Iran seems to be increasing.

"I hope for not only no nuclear attacks on non-nuclear nations, but no attack on Iran of any kind," he said. "That seems so disastrous we felt it was absolutely essential for a real binding regulation."