Working Tractor Beams, Not Just Sci Fi

The tractor beam in action suspends a small particle over an optics table.

You know that one scene in Star Wars where the Millennium Falcon is captured in Death Star’s tractor beam and is pulled in. Sure you do. Anyways that’s still not possible. But if you needed to move a couple of small particles say five feet; you can now do that.


Using only light, Australian researchers say they are able to move small particles almost five feet through the air. This is more than 100 times the distance achieved by existing optical “tweezers,” the researchers say.


Unlike the tractor beams in Star Wars, these ones work by shining a hollow laser beam at an object and taking advantage of air-temperature differences to move it around. The air around the particle heats up, but the hollow center of the beam stays cool. The heated air molecules keep the object balanced in the dark center. But a small amount of light sneaks into the hollow, warming the air on one side of the object and nudging it along the length of the laser beam. Researchers can change the speed and direction of the glass object by changing the lasers’ brightness.


To my surprise, moving particles with powerful lights is not a new technology. Researchers have long been using optical tweezers to pluck bacteria-sized particles and move them a few millimeters. The U.S. Secretary of Energy, Steven Chu, won his Nobel Prize for work with optical tweezers. But Andrei Rhode and colleagues at the Australian National University say their new laser device can move glass objects hundreds of times bigger than bacteria, and move them a meter and a half or more. Rhode says the 1.5-meter limit was only because of the size of the table where he placed his lasers; he thinks he can move objects up to 10 meters, or about 30 feet.


Evidently the tractor beam system needs heated air to work, so currently, it won’t work in space. So no Millennium Falcon grabbing beams yet.