WASHINGTON — THE world's first nuclear test was named Trinity. It lit the sky over New Mexico on the morning of July 16, 1945, marking the dawn of the atomic age. Physicist Edward Teller, later pioneer of the hydrogen bomb, saw desert winds quickly twist Trinity's mushroom cloud into an immense question mark. At the time Teller wondered if the symbolism was significant.
Today, forty-nine years and thousands of experimental explosions after Trinity, the question is whether the time for a treaty banning nuclear testing has finally arrived. A crucial round of United Nations-sponsored test-ban talks opening today in Geneva may reveal the answer.
Clinton officials strongly back a comprehensive test ban (CTB) and think it a realistic goal. The other big nuclear powers - Russia, Britain, France, and China - all support a ban, though with varying degrees of enthusiasm.
But some experts say negotiations are bogging down. They worry that if a CTB isn't ready by early next year, national elections and a scheduled international debate on nuclear nonproliferation could destroy the balance of forces that has made a test ban possible.
``Things are not going as fast as expected,'' admits a US official, ``but the bottom line is everyone is still negotiating in good faith.''
A group of nuclear scientists first began campaigning for a test ban in 1945 as a way to check an arms race they forsaw spiraling out of control. Off and on, a comprehensive test ban has been a goal of US presidents for decades - Dwight Eisenhower started the first formal negotiations with the Soviets in 1958. John Kennedy settled for the 1963 Limited Test Ban Treaty, which still bans tests in the atmosphere, underwater, and outerspace. Richard Nixon signed a pact limiting tests to 150 kilotons of explosive force.
Jimmy Carter made progress toward a comprehensive ban, only to have talks fall apart after the Soviet invasion of Afghanistan. Presidents Reagan and Bush felt that as long as the US possessed a nuclear arsenal, tests were necessary to ensure its safety and pursue new designs.
President Clinton reversed that stance, and serious negotiations among member nations of the UN's Conference on Disarmament began last January.
The third round of these talks, which open today, are expected to run until Sept. 7. The last round failed to produce a draft treaty, as expected; US officials now hope to have a draft in hand by September.
One of the stickiest unresolved issues is the CTB's scope. A nuclear explosion, it turns out, is not as easy to define as one might think. So-called ``hydronuclear'' tests use minute amounts of fissile material and produce blasts equal to that of a small conventional charge; the US, Russia, France, and Britain would all like to be able to conduct some level of such testing.
Verification is another problem, as it often is in arms-limitation talks. Russia, along with most nonaligned nations, favors a bare-bones approach of seismic and radionuclide detectors, backed by spy satellites. Others, including the US and Britain, want a more elaborate verification regime, including fancier gadgets such as hydro-acoustic monitors. The nations involved in the CTB negotiations have also yet to agree on just who will have to sign up before the pact becomes official.
Should it be just a certain number of states, say 40, as the Swedes have recommended? Or should it be an inclusive list, including the five big nuclear powers, as well as all nations with nuclear reactors or research programs? The CTB's fate, however, may be more dependent on two political issues than on unresolved technical disputes. Specifically, will France and/or China block treaty action in the short term? Will the US show leadership in pushing the pact to a conclusion?
China is the only big power not observing a test moratorium. It blew off a nuclear weapon as recently as June and has said it needs more tests before it can agree to a CTB, preferably in 1996.
The French defense establishment similarly is prepared to hold tests if a right-of-center candidate wins presidential elections in May, and doesn't want a ban to take hold until '96.
Experts worry that if China and France manage to slow progress, the whole CTB effort could come apart as the US election cycle starts up. More US leadership may be needed to overcome this obstacle, they claim.
``The dilemma that the administration faces is: Do we proceed on a fast track ... at the risk of alienating two nuclear powers we need for the treaty to enter into force?'' says Michael Krepon, president of the Henry L. Stimson Center, a Washington defense think tank.
More than just the test-ban treaty itself may be at stake. The Nuclear Non-Proliferation Treaty (NPT) is up for renewal in 1995, and many developing nations are beginning to grumble that if the big powers won't stop nuclear testing, they shouldn't have to abjure nuclear possession.
``The fate of the NPT is hanging in the balance,'' insists Joe Cirincione, executive director of The Campaign for the Non-Proliferation Treaty.