News that Israeli airplanes had destroyed an Iraqi reactor was preceded several hours by news of a train wreck in India in which it was feared a thousand people had died. Unrelated incidents, to be sure -- except they are, and terribly so.

Monday morning, before details about the Israeli raid were released, it struck me that I had read nothing in The Post about the train wreck reported on Sunday night's late TV news. On closer examination I found a one-column headline back on Page A11 in the midst of foreign news items, "Indians Die on Train Blown in River." A gale, or cyclone, had blown the train off a bridge into the swollen Bagmati River. The wreck was said to be the "biggest and worst in living memory."

The following day brought a smaller item buried on the last page of the first section. As many as 3,000 might have died in the wreck, it was reported. Nothing more on the disaster appeared until Thursday. This time, even briefer and farther inside, frogmen were reported as still scouring the river bottom for bodies from the train wreck -- now described as "believed to be the worst in history."

Something more profound than an example of relative news values between train wrecks in India and air raids in the Middle East binds these two incidents together. The dimensions of such human catastrophe are too horrible to contemplate -- and so we don't. The staggering loss of life in one becomes so large as to be incomprehensible and therefore virtually nonexistant; we brush it aside as it it hadn't happened. The potential loss of life in the other looms so enormously that we cannot deal with the scope of such a calamity; we put it out of mind and go about our business, just as we have been doing for the last 36 years of the atomic age.

Herbert Scoville Jr. was, as he said, frankly gloomy. He was musing aloud about the spread of nuclear weapons, the dangerous international tensions again rising, the American plans to increase military spending dramatically, the new strategic talk in Washington about the winability of "limited" nuclear wars, the lack of any real debate about arms control in the country.

"Somehow the public doesn't seem able to grasp the significance of it as an issue," he said. "They read these numbers -- 50 million will be killed in an atomic attack, whole cities wiped out -- and it's nothing they can conceive of. It has no meaning in their day-to-day lives. If an airplane crashes and 75 people are burned up, that's a disaster which everybody can visualize. They can picture themselves being in the airplane. But a nuclear war that destroys our society -- that tends to be just numbers. It's too depressing and they don't see what they can do about it anyway."

Scoville brings more than casual knowledge to the subject of atomic weapons and nuclear proliferation. He has been intimately involved in the development of America's nuclear arsenal, and with efforts to bring it under control. As a physicist, he worked with the Los Alamos Scientific Laboratory, directed the Defense Department's weapons test program from the late 1940s into the mid-1950s, headed the scientific section of the CIA and was the agency's deputy director for research until named by President Kennedy as assistant director of the U.S. Arms Control and Disarmament Agency. In recent years he has been active in the nongovernmental Arms Control Association.

Along with everyone else, he has been reflecting on the implications of last week's Israeli strike. "There's no question in my mind the Iraqis were trying to build up the capability of having a nuclear weapon," he says, "and obviously that's a terrible thing. We should do everything we can to stop it. But that's not the way to do it. That's just madness. If anything, it's going to make matters much worse. Here are the Israelis, whose hands certainly aren't clean in this particular area. Everything I know makes me believe they have nuclear weapons of their own. And to sit there and say we have the right to destroy any nuclear installation of yours which is potentially a weapons installation is just asking for retaliation back. It's also going to spur all the other nuclear programs under way.

"You can't stop this indefinitely by force. You can't just go around bombing all over the place. The use of force is not the way to deal with it. But having said that, I don't think we've dealt with it very well either. . . . There's never been any real halt to the nuclear weapons program. It continues to increase -- and not only in numbers. What worries me more than numbers are the technologies being acquired. We are developing smaller, more accurate, more easily deliverable nuclear weapons systems, therefore ones that are essentially first-strike weapons. These are technologies that, in five years and extending on into the future, are going to make it more likely, and more desirable, for these weapons to be used. That is the real danger."

Two years ago, the CIA and Defense Department brought together a group of experts and asked them to think what the world of the 1990s would be like as nuclear weapons continued to spread. The colloquium began with certain basic assumption:

The 1980s likely would be "a trying decade for the United States." The world energy situation would become more critical. Rising population worldwide would place greater pressures on available food supplies. Gaps between rich and poor nations, industrial and non-industrial, would widen. Terrorism would intensify and spread. And despite the best efforts of the United States and other nations, the trend toward the spread of nuclear weapons and nuclear technology would gain momentum.

In that context, anywhere from 12 to 24 countries would possess nuclear weapons by the 1990s, and a large number of nuclear reactors would be operating on all continents. At least 50 nations would have the capacity to develop nuclear weapons. As one of the participants in that forum concluded:

"The chances that nuclear weapons will be fired in anger or accidentally exploded in a way that prompts a nuclear exchange are finite, though unknown. Those chances increase as the number of nuclear states grows. More is therefore worse. . . . If nuclear weapons are acquired by countries whose governments totter and frequently fall, should we not worry more about the world's destruction than we do now? And if nuclear weapons are acquired by two states that are traditional and bitter rivals, should that not also foster our concern?"

For nearly two generations the world has learned to live with the reality of nuclear weapons. And we have lived in a fool's paradise. Because nuclear weapons have not been employed since that August day of 1945 over Nagasaki, we seem to have concluded they have helped to safeguard the peace. We have continued to add to their numbers, watch them spread throughout the world, and have tried to put the unpleasant subject out of mind.

The Israeli preemptive strike brutally reminds us of other realities. If it forces us, finally, to face the harsh facts of nuclear proliferation and the increasing likelihood that deadly enemies other than Arabs and Jews will soon possess atomic weapons -- Pakistan vs. India, Brazil vs. Argentina, North Korea vs. South Korea -- it might achieve something useful.

Might, that is, with one of history's terrible ifs : Useful only if nations understand nuclear war is not an act of God about which we can do nothing, like a cyclone plunging a passenger train into a swollen river, but an act of man that dictates we control what today appears more and more to be uncontrollable.