Non-stop art: why Doug Aitken is a man on a mission

He’s blown up his house, recorded the Earth’s tectonic plates, and worked with everyone from Tilda Swinton to Giorgio Moroder. Now the multimedia artist is taking over London’s Barbican. How does he find the time?I am standing in a crowded gallery in London, looking up at a sculpture on the wall. It is a simple enough piece, three ostentatiously large 3D letters made from bluish glass, but the word they spell out – NOW – seems to drown out everything in the vicinity. The pretentious ch