Chinese physicists reckon they've figured out the tech behind a staple of science fiction: the tractor beam. Fudan University's Jun Chen and team found a way to create a backward pulling force from a forward propagating laser beam, basically turning the photons into a tiny tractor beam.
When we say tiny, we really mean it; this isn't going to snatch a Klingon Bird of Prey out of the sky and drag it into your cargo bay. Currently, the system will only work if the momentum in the direction of propagation is sufficiently small - basically beams that simply glance off an object - and if the photos can simultaneously excite several multipoles within the particle.
That excitation causes the beam to scatter and, if it's at the right angle, work against the direction of momentum. Space capture isn't the scientists' end goal, however; they believe the system could be useful for manipulating particles at the nano level.
[via Technology Review]