Tractor Beams Are a Reality!

But They Don't Work in Space ...

by Mark Newton

 

When it comes to fighting space battles, I can imagine nothing more annoying than getting caught in a tractor beam - just ask Han Solo or Captain Picard. I mean, it's simply bad sport in my opinion.Although tractor beams usually only exist within the massive expanse of science fiction, they may soon be coming to a galaxy near you! Scientists at the Australian National University have actually managed to build a tractor beam which can move objects!

OK, before you get too excited by imagining giant lasers moving planets, I should stress the tractor beam is currently only able to move particles which are about one fifth of a millimeter in diameter. However, they were able to move them 20 centimeters (7.8 inches), which is actually rather impressive as far as I'm concerned. Lead researcher Wieslaw Krolikowski is certainly proud of his work, telling the Guardian:

Demonstration of a large scale laser beam like this is a kind of holy grail for laser physicists.

How Does It Work?
The beam is able to attract or repel objects by utilizing a single hollow laser beam which is described as "bright around the edges and dark in its center."
The laser is used to transfer energy across the surface of the object, this energy is then absorbed resulting in hotspots on the surface. Air particles which collide with these hotspots heat up and jump away from the surface - causing the particle to repel in the opposite direction.
What Can It Be Used For?

Well, in its current form, I wouldn't expect it to be much use for towing space cruisers. Indeed, the fact it requires air to function means it would not work in the vacuum of space - which might disappoint many.However, the researchers have hypothesized that their creation could be used for controlling atmospheric pollution or for the retrieval of tiny of dangerous particles for sampling.
What's Next?
It seems that following this initial demonstration, the tractor beam team are eager to scale up the experiment to move bigger objects for longer distances. Co-researcher Vladlen Shvedov claimed:

Because lasers retain their beam quality for such long distances, this could work over meters. Our lab just was not big enough to show it.