A viewer floats through a mysterious, semitransparent landscape, like a diver underwater. Breathing in, the person rises through the bare branches of a huge tree. As the person enters the branches, their empty twigs suddenly become covered with leaves. The viewer then breathes out and drifts down, down, into the rocky soil on which the tree stands. Now the viewer gazes upward into the tree's roots.

This was the experience of people who entered a room containing an art installation called Osmose, a French word meaning "flows through." Osmose, designed by Canadian artist Char Davies and first exhibited in 1995, is one of many examples of art that uses virtual reality. Viewers of Osmose wore head-mounted displays as well as devices, invented by Davies, that fitted around their chests and sensed their breathing...