SCIENCE FICTION films can really cheer you up when you think about everything that hasn't happened. On the Beach, made in 1959, speculated on the consequences of nuclear holocaust in 1964. And 1984 -- the version made in 1956 and the version made in 1984 -- has come and gone with less electronic oppression than we might have expected.

The thought police, in the meantime, are busy fighting terrorism in Terry Gilliam's futuristic Brazil, now playing at the Outer Circle. The Monty Python Circus performer projects an Orwellian future frustrated with random bombings and faulty state-run central air-conditioning. This bizarre comic cautionary film won the Los Angeles Film Critics Best Movie Award in 1985.

A possible double bill for future urban planners might also include Fritz Llent classic Metropolis, about a mechanized city and an oppressed society, re-released in 70mm with color tints and a score by Giorgio Moroder of "Flashdance." The worker heroine of the first has much in common with Jennifer Beals.

And there's also a delightfully dated musical comedy from Fox called Just Imagine, made in 1926 and set in New York in 1980, when there were flying cars and the occasional Martian. Buck Rogers later made use of the state-of-the-art sets.

Science-fiction isn't as oracular as it is historical, often affording an absurd retrospective of human neuroses, fears and woes. The Invasion of the Body Snatchers, cowritten in 1956 by Sam Peckinpah, remains a classic example of the cold war shivers. It was remade in 1978 with Donald Sutherland and Brooke Adams pursued by the pod people, aliens who turn humans into unemotional zombies. Either version is worth viewing.

People are terrified of losing their souls, their selves and their sexuality. Zombies, fungus, even women's liberation have potentially threatened the autonomy of man. In 1974's Planet Earth, for instance, John Saxon became a prisoner of a female- dominated society in the year 2133. Luckily, he taught those girls a thing or two and the world was saved.

One year into the Carter administration, Steven Spielberg released Close Encounters of the Third Kind to begin an era of divine intervention from space.

Spielberg's musical spaceship has since inspired the endings for such starfare as Cocoon; Uforia, a country and western, fundamentalist sf now at the West End Circle; and Starman, with Jeff Bridges as a space messiah. Still no second coming for E.T., and the genre seems to be fading with the coming of strong terrestrials like Rambo and Ronald Reagan.

Whatever science discovers, science fiction debates. The Incredible Shrinking Man, directed by '50s master Jack Arnold, begins to diminish after passing through a radioactive cloud; The Incredible Shrinking Woman, a Jane Wagner comedy, sees Lily Tomlin diminished by air pollution and junk food.

The nuclear nightmare has persisted as a focus for our fears for more than 30 years. And the apocalyptic landscape gives us some of our best action adventures in recent years. Mel Gibson stars in the superb action adventures from the Outback -- Mad Max, The Road Warrior and Mad Max: Beyond Thunderdome. They're violent, visually brilliant parables from the Wasteland, where Max encounters gangs of punk bikers and spunky refugees.

The Terminator, a camp, fast-paced adventure, features Arnold Schwarzenegger as an unstoppable android assassin from the future sent back to murder the mother of a pesky rebel leader.

The Day the Earth Stood Still, a 1951 classic with Michael Rennie as Klaatu, is still tops in the no-nukes genre.

The Japanese have capitalized most on atomic angst, with their out-sized, polyurethane monsters. Godzilla vs. The Thing and Mothra are a couple of my favorites, owing to the weensie charms of Mothra's guardians, the six-inch Alilenas twins, who sing and talk in unison.

Japanese movie moguls are at their most inventive with Attack of the Mushroom People, which finds a group of tourists shipwrecked on a desert island, attacked by fungus and turned into giant toadstools. (Day of the Triffids and Attack of the Killer Tomatoes are other alternatives for those who fear vegetables.)

A veritable mutant menagerie awaits movie goers -- irradiated ants, conservationist frogs and trained piranha. The last were created by filmmaker John Sayles, a genius-grant winner who wrote the screenplays for both Alligator and Piranha. In the first, a giant alligator named Ramone finally eats a cadillac to interest the upper classes in the destruction of the masses. In the second, the government has trained killer fish to attack the North Vietnamese.

Sayles, who made non-sf movies such as Return of the Secaucus Seven, also wrote and directed the estimable race parable Brother From Another Planet, in which a black alien is shipwrecked on Ellis Island and makes his way to Harlem.

This low-budget effort (currently viewable on cable and video) serves as a parody of the genre as do the current, clever, new wave sf comedies -- Repo Man in which Emilio Estevez flies off into the heavens in an old sedan, and Android, one of the most charming robot movies ever made, with Klaus Kinski as a mad roboticist.

Four androids come back to earth to meet their maker in Ridley Scott's brilliant and beautiful Blade Runner, available on video and worth viewing with an eye to its dazzling effects. Scott's Alien, which has been called a cancer parable by some critics, is also one of the scariest films of all times. A monster invades the body of a crew member, growing larger and larger, finally usurping command of the ship.

Time is not on our side and moviemakers like to explore its infinite impossibilities. Woody Allen's Sleeper is the delightful tale of a health food store owner who wakes up in 2173 to learn that smoking is good for you.

Time Bandits, more sf from Terry Gilliam, is a top-notch time-travel tale, with Craig Warnock as a kid who escapes his dull suburban parents by traveling through time with a gang of thieving dwarves.

Of course, there's Back to the Future, still playing at a few theaters, and the film adaptation of H.G. Wells' The Time Machine, with turn-of-the-century type Rod Taylor exploring the future after a couple of world wars and a 1966 atomic blast.

Sigmund Freud meets Sherlock Holmes in the psychological '70s, in The Seven Percent Solution, a handsome and entertaining adventure story.

We can all prepare ourselves for the worst -- the future probably -- and for whatever befalls us, or falls on us, through science-fiction viewing. The most inspirational options include The War of the Worlds, an early germ warfare movie in which Earth is attacked by Martians who eventually succumb to the common cold; the heroic Star Wars triology; the evolutionary, revolutionary 2001; and last year's glowing Starfighter. Live long and prosper. May the force be with you.