The combined eyes of Puerto Rican artists Jennifer Allora and Guillermo Calzadilla seem to be able to see into the fourth dimension. The artists have been collaborating since 1995, creating sculpture, performance art, and architecture that transform physical space. They have painted quotes of secret desires on flat rooftops that can be viewed by airplane passengers, transposed a painted tennis videogame board onto a real tennis court, and created office window blinds that can be opened or shut by passersby. More recently, they've turned to music as a way to transcend cultural boundaries. For their exhibit at the Walter and McBean Galleries at the San Francisco Art Institute, Allora and Calzadilla took traditional military music and fractured it, creating an opera that was performed by students from the San Francisco Conservatory of Music. In the midst of the gallery, a mountain of broken-apart foam and plaster looms like a snowy white ruin. Recent works in video complete the exhibit, mostly focusing on the artists' participation in protests on Vieques, the island off Puerto Rico that was used by the U.S. Navy as a weapons testing ground until 2003.