It looks like the aftermath of the Big Bang -- of the artistic universe in this case, after modern art rolled itself into a ball and exploded.

"Content: A Contemporary Focus" celebrates the first 10 years of the Hirshhorn Museum and the past 10 years of art.

For want of a better phrase, theyre calling the diversity of this period "post-Modernism." Instead of modernist Frank Stella's "What you see is what you see," what we're seeing now is art that communicates, begs for interpretation and reveals life. The medium is truly the message.

By now everyone has heard about the roomful of nickels at the Hirshhorn -- 50,000, each one topped with a matchhead. Row on row, they represent Soviet tanks, "The Reason for the Neutron Bomb." (Overlooking the expanse of mall, the expense of war.)

Overhead in thatsame room, a Times Square-type sign spells out a stream of "Truisms." To wit: "Confusing yourself is a way of staying honest . . . Dependence can be a meal ticket . . . Expiring for love is beautiful but stupid . . . ."

They're just truisms, but like much in this show, they make you think: Do I believe this? Should I be copying this down?

"Chaos is hell," says one, but this chaos, this quest for something new in art, may lead somewhere. Bold as brass. Nothing much you could ever hang on a wall, they have scope and some even have style.

The show can be happily explored on a purely participatory level: tapes of performances to watch, and a gray maze not to be entered if youre claustrophobic. Bumping along the narrow passages, eyes aching from unrelieved gray walls, your reaction is what it's all about. Also, a noisy, spinning wind-tunnel, "The Savage Sparkler," operates twice daily -- fluorescent lights, heating coils, fans, motors and all.

The art explores spiritualism, semiotics, society and psychology. In this plurality of images and ideas, a scattering of German expressionism (by Jorg Immendorff, Anselm Kiefer), an Andy Warhol piece and gruesome photographs (a conehead madonna and child a la Diane Arbus; corpses' heads that have been sketched over; abattoir art) hold down the walls around the installations: a mannequin getting out of bed to a headlight-sun; a phone-talk jukebox set among musical scores of life; a classical temple of a hundred columns falling into ruin; a lacquered pine lawn chair, just slightly oversized to tweak your perceptions.

A Buddha contemplating himself on TV has the ring of recognition. But be careful not to stub your toe on 96 pieces of "Bluestone" arranged in a semi-Stonehenge pattern.

"Missiles and Bunnies" takes up most of a room.

"I hope it speaks for itself," says artist Paul Thek.

It's an either-or, war-peace tableau. Bunnies hopping among missiles. Skyscrapers becoming building blocks becoming baby blocks. Birthday cake. Champagne.

Whose birthday is it?

"Yours," says Thek, who, putting the final touches on his installation, has one thing alone to communicate.

"The only important thing in the world today is nuclear danger. Art that doesn't explore that is really avoiding the point," says Thek.

"To hell with eternity," he says. "It's now I'm interested in."

In this last comment, Thek has captured the point most of the artists are making. For this truly is a show about today. CONTENT: A CONTEMPORARY FOCUS, 1974-1984 -- At the Hirshhorn Museum and Sculpture Garden through January 6, 1985.