The first locomotive, however, ran out of fuel seven years ago, and there is no clear technology-driven alternative leading sector, like biotechnology, that can inspire similar exuberance, rational or otherwise. The second locomotive began sucking fumes two years ago, and is now coasting to a halt, which means that the third – the US as importer of last resort – is losing speed as well: the weak dollar accompanying the housing finance crash makes it unprofitable to export to the US.