Seeds of change

摘要

One of the most useful pieces of equip-ment in science fiction is the tractor beam. This hypothetical device can be used for grasping hold of pieces of cargo, small spaceships and even asteroids without actually touching them. Pure fantasy, of course. But only because of the size of the things being moved. For, at the scale of molecules, or even living cells, scientists have been using tractor beams for years. The beams in question are lasers. And given the size of the objects being moved, they have become known as optical tweezers. But, cunning though they are, they have been able to move only one thing at a time-which is fine for research, but not much use commercially. That is about to change, though, for a Chicago-based firm called Arryx has found a way to control thousands of these tweezers simultaneously. It thinks the technology has big commercial possibilities, from cleaning blood to building computer memories. But the first application is particularly appropriate to a firm from a city built on the cattle industry: sorting bull semen.