Anthony McCall, Serpentine Gallery, London

The only other time I have come across Anthony McCall's work was as part of a group show at the Hayward Gallery (Eyes, Lies and Illusions, 2004) where his Line Describing A Cone (1973) mesmerised the handful of people that stood with me and watched a point of light seemingly grow (with the aid of dry ice) like a geometric ghost into a cone that hovered in front of us. For some reason none of us thought about breaking the light or walking into the cone. We gazed at it as if it were merely a different kind of sculpture and stood behind a suggested, yet invisible barrier while the 16mm projector worked its magic on the darkened room.

McCall calls his work 'solid light' and it exists somewhere between avant-garde film, minimalist sculpture and immersive installation art. He gave up art in the 1970s to concentrate on book design but has recently returned to his light experimentation.

Line Describing A Cone is here again at McCall's first major retrospective alongside other slightly later works that utilise digital video projection to enable more precise and fluid geometric light patterns. The best thing about it though is that by taking the lead of the dozens of kids that are always around and about this gallery (its right in the middle of Kensington Gardens) and physically entering the artworks a whole new experience is realised.

By varying your position in relation to the projections you can create the illusion of walking through solids or of being partially dissolved by ethereal planes of light. It's part futuristic sci-fi, part ancient ritual, part 1980s rock video. And it's beautiful and exhilarating. Substantial work in the most transitory of mediums.