The future has caught up to Frederik Pohl, master of improbable visions and worlds beyond ken.

His latest novel is a (barely) fictionalized account of the nuclear disaster at Chernobyl. Had he written it before the accident, he said, "It would have been the same damn book. I just would've made it up."

His next is an examination of the planet after the "Star Wars" defense system is put to use; though this one's not yet in final draft, its basic, alarming premise has already been confirmed in major part by analysts at the National Aeronautics and Space Administration.

The sociological science fiction that Pohl pioneered in the '50s, with its dire portrayals of overpopulation, environmental pollution and rampaging technology, is routinely the stuff of television news.

"I was at a science fiction convention the weekend after Three Mile Island, and all the fans were going around saying, 'I told you so,' " Pohl says with a sigh. "If you read science fiction, nothing ever takes you by surprise."

So it goes. Thirty-five years in the starships-and-space-colony game, and what have you got? Six Hugos, two Nebulas, a passel of other writing awards and credibility. A reputation as a seer, of sorts, and the right to be a tad bored with the current crop of the genre.

Some of the hottest new SF writers are penning baroque fantasies, a` la Dungeons and Dragons, and dabbling in the school of "cyberpunk" -- part Six Million Dollar Man and part Twisted Sister. "It's not the cyber part, it's the punk part I don't like," says Pohl. "I presume I'm showing my age."

His age is 67. He sips a glass of milk through a haze of cigarette smoke, the cocked left eyebrow making him look like the skeptical editor he once was and, unofficially, still is.

"In all the books I've read, even the ones that have been winning awards, there's nobody there I can root for. They're all terrible people. I hate them. There's not a character I'd care to have as a next-door neighbor and I'd certainly never let one marry my daughter."

Five years ago, Pohl was elected a fellow by the American Association for the Advancement of Science. ("They said it was for the quality of science in my books. I may be the only member who was a high school dropout.") For a decade, he's trotted the world as a respected lecturer on future studies.

And, more recently, he has become the recipient of a startling outpouring of Soviet glasnost, or something close to it. Well, maybe there are a few surprises left. The next explosion was much louder. The walls shook. Dust sprang out from the walls, hanging like a sudden shimmer of ice fog in the air. The lights went out -- all of them, even the lighted meters and dials on the full-wall instrument board.

"Oh," moaned Varazin, "my God." -- From "Chernobyl: A Novel"

The Chernobyl book wasn't Pohl's idea. His publisher proposed it barely a month after the April 1986 explosion and fire that destroyed the RBMK-1000 reactor in the Soviet Ukraine and showered the world with fallout. "I didn't think I knew enough to write the book properly," he says. "I knew basic theory about nuclear technology but nothing about the RBMK reactors."

A little flimsiness of fact might not have fazed your average SF author, but you don't get elected an AAAS fellow by being sloppy with your transuranic elements. Moreover, Pohl thought the news media had already created quite enough fantasy about the accident, and he didn't have much reason to believe that the Soviets would divulge any more details to him than they had to the world at large.

For one thing, he's been in and out of favor with the Soviet Union over the years, owing to his propensity for saying and writing pretty much what he thinks. He was forced to cancel a series of Eastern European lectures several years ago, he says, "because I had either said that the Soviet Union was a police state, or I said that in the Soviet Union the subways are palatial and the airplanes smell like septic tanks, whereas in the United States it's the other way around."

But as fortune would have it, Chernobyl occurred at a time when Pohl apparently was back on the "in" list.

"My wife and I were going to Moscow to be observers at the Congress of the Union of Soviet Writers. Why they invited us I'm not exactly sure," he says. "I didn't realize I was back in favor until I got the invitation."

What he found there was as mystifying as any of the alien worlds he has created.

"They began having individual writers get up to speak, and they said outrageous things, things that startled me. Everyone talked about Chernobyl, about what a terrible disgrace that such an accident should have been allowed to happen.

"And they criticized some of the major Soviet state plans, such as damming some of the rivers and reversing the flows. Most people who are familiar with the plans regard them as terrible for the ecology, changing it in ways that nobody can really predict."

Speaker after speaker rose, accusing the writers union of corruption, accusing the publishing industry of censorship, of failing to keep important works in print.

"Not everybody, but at least half were saying things that I have heard said in the Soviet Union before, but only whispered behind somebody's back, never in public," Pohl says. "And during one long session, Mikhail Gorbachev was sitting there, listening to it all."

All this was encouraging, but the decision to write the book was made for a reason that was pure Pohl: the element of human response to the impossible.

"It was the massive effect that it had on everybody in the Soviet Union, not just to people evacuated in a hurry but to everybody in the country," he says. "It just wasn't the sort of thing they expected to have happen."

The book was written in seven months and involved an extraordinary degree of cooperation from the Soviet government. In sessions at the Moscow television center, Pohl was allowed to see thousands of feet of film of the burning reactor. "One film taken right after the accident was fogged by radiation," he says. "I'm told the cameraman later died of radiation poisoning."

He was granted interviews with officials from the Ministry of Nuclear Energy, including two who were routed from their beds at 3 a.m. the morning of the accident, less than two hours after the disaster began and more than 36 hours before it was officially acknowledged.

He spoke to firemen who battled the blaze, to a doctor dispatched to the town of Pripyat, to a woman resident who waited anxiously for word of her husband, a plant employe. Standard journalistic practices, perhaps, but not in the Soviet Union, at least not in Pohl's experience.

"The actual accident is exactly as I described it, as far as I know," he says. "It was a kind of glasnost I would not have expected in the Soviet Union until very recently."

How the Soviets will receive the book is anybody's guess. Pohl doesn't even want to guess how it will be received in the United States, devoid as it is of the famous Pohl humor, the satirical lightness that won critical acclaim for such science fiction classics as "The Space Merchants" and "Gateway."

Grim stuff, this "science faction," as Pohl's publicist dubs it. "I don't know how much people want to know about things like that," Pohl says. "I think a great many people would rather not know. They don't want to have to think about it.

"Books like 'Chernobyl' -- in particular 'Chernobyl' -- are designed to force people to think about it. I would like to shake people out of their complacency. If it doesn't, it's not because I didn't try."

He had not really thought about what was going to be done with the ruined core -- dismantled and buried, he had supposed, if he had supposed anything at all. He simply had not realized that it would stay there -- still hot, still deadly -- forever.

-- From "Chernobyl: A Novel"

"The book I'm writing now is about what happens if 'Star Wars' really works, if there is a nuclear exchange and the SDI satellites do exactly what they're supposed to do -- blow up all the missiles in the launch stage," Pohl says. "It works exactly the way Ronald Reagan wants it to work."

What happens is that the 50,000 or so trackable bits of debris in orbit become millions or billions of trackable objects, each the size of a monkey wrench or larger and each packing a four-mile-a-second destructive punch. The scenario was pure conjecture on Pohl's part -- until a recent NASA study came to the same conclusion.

The result: "A picket fence in space that you can't get through." End of space program. End of voyages to the planets, the stars and beyond. The human race trapped on Earth -- forever.

Superimpose a full-fledged AIDS plague, add a sprinkling of radiation and a collapse of governmental institutions ("Washington is wiped out, of course. I always wipe out Washington.")

Near-term stuff, in the spectrum of science fiction, but then what's far-term anymore? "I'm trying to see all the things that could go wrong and have them all go wrong at once, and see how people manage to get out of it," Pohl says. Or if they manage to get out of it?

He shrugs. "If I can find a way for them to get out of it, they get out of it. If the logic of the story is such that they can't, then I let them all die."

Pohl didn't always write this way. "When I was editing a magazine called Galaxy, I bought a lot of stories by Robert Silverberg," he says. "And every time I bought a story I'd call up and say, 'Bob, this one is even more depressing than the last one. Cheer up, for God's sake.' Then I published a novel called 'JEM,' which is really a down-deep book, and I got a post card from Bob saying, 'Glad I finally converted you.'

"But in that book, I had nowhere to go. After I set everything up, I didn't believe there was any way out of it." A pause. "It won the American Book Award."

Pohl, who began reading science fiction as a teen-ager during the Depression, once said that people were attracted to the genre for two reasons: The first because it was a way out of a bad place; the other, that it was a window on a better one.

After the "Star Wars" novel is finished, he says, "The next book I want to write is a book I've been meditating for 30 years now. It's the history of the Great Depression."

The future has caught up to Frederik Pohl. It appears to look a lot like the past.