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Tractor Beam Me Up

Have scientists created a real-life prototype of a tractor beam, that glowing shaft of green light that the folks on the Starship Enterprise use to seize hold of enemy vessels? I'm a sucker for any innovation that brings us a step closer to gallivanting around the universe, boldly going where no one has gone before. But this tractor beam won't be coming standard on next year's spaceships. That's because it works by heating up the air around the tiny particle it's trying to move. In the vacuum of space, that's a deal-breaker.

The new tractor beam was built by researchers at the Australian National University, and it can manipulate tiny (0.1 millimeter) carbon-coated glass beads from more than five feet away. Scientists have long been using devices called optical tweezers to move even smaller objects, right down to  the size of single atoms, but the new beam extends the maximum distance over which particles can be prodded a thousand-fold. It also operates in plain air, unlike optical tweezers. Compared to a delicate  tweezer, the new tractor beam looks like a pair of overgrown kitchen tongs.

How do the tongs work? A hollowed-out laser beam called a vortex beam, bright at the edges but dark in the center, grabs hold of an object--preferably something very lightweight that doesn't conduct heat well, like the carbon-covered bead. The laser heats up the air surrounding the bead, while the unilluminated gutter in the center of the beam stays cool, suspending the glass bead inside the beam. Because the laser light flows in one direction, it also gives the bead a little shove along the beam's path. With two beams, set face to face, one could manipulate the speed and position of a particle at will.

Why would you want to do that? Scientists are still brainstorming possible applications, like assembling tiny devices and safely transporting hazardous materials--provided, that is, that the laser doesn't cook everything it touches. No, it's not "boldly going where no one has gone before." Let's just say it's "boldly manipulating tiny things over meter-scale distances." Engage.

User Comments:

Still, pretty cool.

...manipulate the position and speed of a particle.... I wonder if we could use this to find a hole in Heizenburg's Uncertainty Principal.

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