As a newspaper reporter you get used to all sorts of funny assignments and mine have included politics, debates, and wars, but the most arresting, I believe, was a conference this winter of noted scientists (Oct. 31-Nov. 1) on ''The World After Nuclear War.'' It was at a conventional hotel; the uniformed doorman let us in at the revolving door; the half hundred or so celebrities looked quiet, normal, and everyday enough, only they were forecasting that civilization might end. Not merely civilization, but all life on planet Earth. They were serious about it. How do you cover a story like that?
They had satellite images projected on triple screens coming from Moscow with translated statements from members of the Soviet Academy of Scientists. Four Soviet and four US scientists asserted that ''a nuclear attack would be suicide for the nation that launched it, even if there were no retaliatory strike.''
The US scientists were quiet and matter-of-fact. They were reporting on studies that had been made in the last year or so. They were authorities like Carl Sagan of Cornell University and Donald Kennedy, president of Stanford University.
Last month in the Senate Caucus Room much of the earlier testimony was repeated. Listeners pondered. Maybe these experts knew what they were talking about; maybe it was exaggerated.
But the difficulty for the ordinary listener was adjustment: how to go from this creepy hearing into the everyday world, with overcoated bystanders waiting for buses, or the shops decorated with holiday festoons. How is man supposed to keep pace with this strange new world? At Hiroshima suddenly the nuclear bomb appeared . . . and now this awesome new knowledge. The relations between Russia and the US are as bad as they ever have been. So what comes next?
The scientists contended that the ultimate danger of nuclear war is not the immediate concussion and blast of exploding missiles but the effect on the environment, the adjustment that makes life possible on Earth. When the missiles go off they may blow up soil and dust and smoke that create a cloud over the earth. Sun rays can't penetrate it. That drastically lowers temperature (30 or 40 degrees, maybe) and this creates a ''nuclear winter.''
This might be only one of the ill effects. Some evidence of this comes from observations by instruments on the Mariner 9 which, in 1971, went into orbit around Mars. It reported that the planet was enveloped in just such a dust storm as might come to Earth. A catastrophe to the climate might follow. Biological chains would cease functioning on land and sea; crops wouldn't grow. Stanford University's Paul Ehrlich told the conference, ''Virtually all land plants in the Northern Hemisphere would be damaged or killed.'' Others went beyond that. (It's hard to hold back the scientific imagination, but who knows? - who would have predicted the nuclear bomb?)
I don't suppose there has ever been a time when the human experience was supposed to make such jumps as now.
This concept of ''nuclear winter,'' I notice, is making progress in the public prints though here in Washington it is only just entering political discussion of international relationships.
Magazines are breaking the way. Thirty-nine pages of a two-part article by Jonathan Schell, who wrote ''The Fate of the Earth,'' are now appearing in New Yorker magazine, and currently Atlantic Monthly offers a 20-page article by Thomas Powers on nuclear annihilation. They are not happy articles. They agree in effect that mankind has got itself into an awesome trap from which it doesn't know the way out.
It certainly would be helpful if our leaders could calm down their epithets; if they could improve diplomatic relations. We are hardly on speaking terms with Russia and they reciprocate our fear.
Surely in a crisis like this new efforts at communication are essential. As Thomas Powers says about warfare: ''In the past when somebody lost, somebody won. Now nuclear weapons make that unlikely.''