Fun (and Profit) With Actual Tractor Beams


Once again, everything I wanted to know about the future I learned by watching Star Trek,…

Scientists successfully created (albeit on a small scale) an actual demonstration of a tractor beam.

For those of you who are not trekkies, the notion behind a ‘tractor beam’ was that some sort of energy beam would emanate from a spaceship onto an object – say, an asteroid – and either move it aside or pull it along; and all this without cables! Pretty cool, but that’s just science fiction, right?

Wrong. A group of physicists have built their own tractor beam in the lab by using an optical beam to pull a 30 micrometer silica sphere suspended in water (okay, so it’s something you can just see with the naked eye, but the demonstration proved that a tractor beam can actually exist).

Nothing magical or off the wall: just a working example of a Bessel Beam. A Bessel Beam is a field of electromagnetic, acoustic or even gravitational radiation whose amplitude is described by the Bessel function. A true Bessel beam is non-diffractive – which means that as the beam propagates, it does not diffract and spread out – like sound or light normally does – and, in fact, can be focused down to a small spot.

The applications are tremendous: moving heavy objects at will, offering potentially greater savings and worker safety; the construction industry, along with moving services and a host of others would benefit from this advancement.

Sounds great, but before you rush out to the store to get your own tractor beam, hold on: there’s a whole lot more work to be done. As reported in PhysOrg:

…the tiny tractor beam may not be scalable — at least not for the foreseeable future. The creation of a space-based tractor beam like the one portrayed in Star Trek would require a tremendous amount of energy — enough to destroy the object that it’s trying to pull in. But that said, the breakthrough indicates that a similar device might be possible by using a less energy intensive energy source.

And of course, you know what that means: it’s going to be a awhile before we’ll be carrying our own pocket version of Bessel / Tractor Beams on our key chains, going to the nearest sports bar and using your beam to get a bottle of beer or doing some other cheap parlour tricks (Ah, what the future brings: I can just see the sexual harassment lawsuits growing in leaps and bounds,...).

The Ruffner and Grier paper was published in Physical Review Letters and can be found here: http://prl.aps.org/abstract/PRL/v109/i16/e163903

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