Laser physicists from Australia have just built a reversible "tractor beam" capable of moving tiny particles.

This tractor beam--the world's first-ever--has moved particles one fifth of a millimeter in diameter to a distance of 20 centimeters. It's a long way off from the tractor beams in science fiction shows like Star Trek or Star Wars, but it's a good start.

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Wieslaw Krolikowski of Australian National University (ANU) said this feat is about 100 times further than previous experiments.

These experiments conducted at the University of Saint Andres relied heavily upon the motion of photons to propel particles on a microscopic level.

The ANU experiments, on the other hand, used the laser a little bit differently. Rather than working on photon momentum, scientists used heat instead.

A laser beam is hollow. It's bright around the edges and dark within its center. It can repel and attract objects.

The energy from the laser hits the particles and travels across its surface. It's then absorbed, creating hotspots on the surface.

Air particles that collide with the hot spots heat up and shoot away from the surface, causing the particles to recoil in the opposite direction.

To move and steer the particle, the team controls the polarization of the laser beam to heat up the desired portion of the particle's surface.

"We have devised a technique that can create unusual states of polarization in the doughnut shaped laser beam, such as star-shaped (axial) or ring polarized (azimuthal)," said Dr. Cyril Hnatovsky of ANU.

This allows scientists to move smoothly from one polarization to another, thereby stopping the particle or reversing its direction.

This technology is versatile and could be used to help control atmospheric pollution. It can also be used to retrieve tiny, delicate, and dangerous particles for sampling.

TagsTractor beam, Star Trek, Star Wars, Australian National University, Cyril Hnatovsky