The ground-floor lobby of the Sackler Gallery is now home to a peculiar kind of shipwreck: the 50-foot-long hull of a massive wooden fishing boat, run aground on a wide white beach of gleaming porcelain knickknacks.

The imposing installation stands guard in the museum's narrow lobby, creating a bottleneck for those wishing to enter. Face to face -- face to hull, really -- visitors confront some of the favorite ideas of contemporary Chinese-born artist Cai Guo-Qiang: clashes of culture, of past and present, and of tradition and innovation. One half of a two-part show called "Cai Guo-Qiang: Traveler," now on view at the Sackler and the Hirshhorn Museum, the shipwreck piece introduces us to an artist steeped in contradictions and intent on bridging gaps between them.

The pockmarked, rust-colored hundred-year-old hull, dredged from the coast of Japan, imposes on our space with a menace akin to that of sculptor Richard Serra's steel walls. The ship is marooned on an equally imposing, if bizarre, white "ground": a massive pile of broken porcelain -- several tons in all -- including slivers and shards of dinner plates and coffee cups alongside hundreds of Barbie doll-size Buddhist statues. The effect is something like that of visiting a china shop, post-bull.

Cai, now a New Yorker, incorporates the porcelain as a nod to his Chinese roots -- the ceramics were made near the artist's home town of Quanzhou; the figurines represent Guanyin, a bodhisattva whom the artist reveres. At the same time, he turns tradition on its head: Showing cheapskate figurines by the jillions challenges the accepted notion that a museum should house sacred objects, shown a few at a time.

Cai's reverence for history and penchant for iconoclasm helped generate this unusual two-part exhibition. In talks with Sackler curators, he decided to address both sides of his identity by straddling two institutions: The Hirshhorn's ongoing "Directions" exhibition series hosts cutting-edge artists; the Sackler's rooms show Asian art. Cai counts himself a member of both camps. The Sackler installation represents a break from the norm for Cai, who is best known for working in gunpowder. He stages exploding pyrotechnic shows that often last just a few minutes. Like the works of Christo and Jeanne-Claude, the projects are ephemeral installation art in a civic or landscape context. Vulnerable to vagaries of weather and the volatility of his medium, Cai's ambitious projects fail as often as not.

The works are political but with a benevolent, peacemaking bent. The fireworks coordinated for New York's Central Park last year, though mostly extinguished by rain, served as both a tribute to the park on its birthday and a fiery resurrection for the terrorism-scarred city. A daytime piece for a Southern California air show last month, which used smoke instead of fireworks, injected peaceful aerial landscape painting into a show of military might. The artist also reaches for the broadest possible audience, going so far as to dedicate pyrotechnic works to extraterrestrials, hoping his fireworks can be viewed from the heavens.

At the Hirshhorn, the single-room gallery show "Unlucky Year: Unrealized Projects from 2003-2004" assembles nine studies -- for cities such as Paris, London and Washington -- that were never carried out. The implication of the title is that bad luck explains why these projects were never completed.

Truth be told, Cai isn't unlucky. He's a dreamer.

Hirshhorn visitors can pick up a booklet the artist made to accompany the show, detailing plans for each project and explaining why it didn't happen. A common theme emerges: Cai asks the impossible. In a post-Sept. 11 world, he requests that, for the project "Bird of Light," planes travel alongside bursts of fireworks during an air show. For "Movement Cultivates Vitality," he wants pyrotechnics to be launched near major rail lines. For "Building Chinese Tower in Paris," he asks -- gasp -- that officials of France and China cooperate.

It's easy to write Cai off as slightly bananas, yet there's something sweet about his refusal to account for reality. And, when the installations don't pan out, he is left with a series of surprisingly quiet, peaceful images. Drawings are made from a series of small-scale gunpowder explosions on massive pieces of paper. Cai has managed to control the explosives' destructiveness by suffocating the blasts with rocks and cardboard. The mini-explosions that travel his fuses carve burred lines onto paper without destroying it. (Yet, as a video screening in the Hirshhorn lobby shows, the situation can get tense as assistants scurry to put out rogue flames after each piece is lit.) The lines could be etcher's marks writ large. Some projects, such as "Movement Cultivates Light," end up looking like lovely landscapes where a stand of trees hugs a ridge. Others look a bit like the skeletal outlines of the building where the project is sited, as in a design for an escalator project for Paris's Pompidou Center.

Such quiet, beautiful drawings make a stark contrast to the aggressive properties of gunpowder. Yet fireworks and light shows connote benign desires -- to be wowed and mystified -- alongside destructive ones. Like star showers and eclipses, they evoke childlike wonderment. Cai is a poet, for certain.

Cai Guo-Qiang: Traveler, at the Smithsonian's Arthur M. Sackler Gallery, on the Mall at 1050 Independence Ave. SW, and at the Hirshhorn Museum and Sculpture Garden, on the Mall at Seventh Street and Independence Avenue SW, to April 24. Both museums open daily from 10 a.m. to 5:30 p.m. Call 202-633-1000, or visit www.si.edu. Admission is free.

Small-scale gunpowder explosions carve burred lines onto pieces of paper in Cai's proposal for Expo 2005 in Japan.Doll-size Buddhist statues and shards of plates form a beach for Cai's hull.