Is The Death Star’s Tractor Beam Possible?

Tractor beams have been a prominent feature in science fiction literature, comics, and films since the 1930s, popular for their captivating ability to attract an object to another from a distance. While the concept may seem light years away, researchers have had some success in replicating the method on a microscopic level since the 90s.

Last month saw a breakthrough in tractor beam research, with laser physicists at the Australian National University (ANU) demonstrating a working reversible tractor beam that can not only attract but also repel objects.

Thought to be the first long-distance tractor beam in the world, the laser physicists at ANU succeeded in moving particles one fifth of a millimetre in diameter a distance of up to 20 centimetres. It is believed that this distance is around 100 times further than any previous experiment.

‘Hollow’ laser beam technology

Up until now, tractor beam experiments have harnessed the energy of light particles or photons to create motion, but the device constructed by ANU uses the energy of the laser as it heats the particles and the air around them.

The recent research used a ‘hollow’ laser beam, which is dark at its centre and bright around the edges, to manoeuvre tiny hollow glass spheres about a fifth of a millimetre wide. Energy from the laser hits the glass sphere particles trapped at the dark centre of the beam, creating surface hotspots on them.

Upon colliding with the hotspots, air particles heat up and bounce away from the surface, causing a backfire motion in the opposite direction on the surface of the glass spheres. The laser physicists at ANU were then able to manipulate the glass spheres by changing the laser beam’s polarisation to move the position of the hotspots on their surface.

Co-author of the project at ANU, Dr Cyril Hnatovsky, said "We have devised a technique that can create unusual states of polarisation in the doughnut shaped laser beam, such as star-shaped or ring polarised."

"We can move smoothly from one polarisation to another and thereby stop the particle or reverse its direction at will."

Dr Vladlen Shvedov, Dr Hnatovsky’s co-author continued, “Because lasers retain their beam quality for such long distances, this could work over metres. Our lab just was not big enough to show it,” said co-author, Dr Vladlen Shvedov.

Speaking of the project, Professor Wieslaw Krolikowski from the Research School of Physics and Engineering said “Demonstration of a large scale laser beam like this is a kind of holy grail for laser physicists.”

So, is the Death Star’s tractor beam possible? Someday perhaps. But for now, only if the Millennium Falcon is shrunk down to the size of a particle.

What’s next for lasers?

We’ve covered several stories about the impact of laser on our everyday lives. For example, surgery to remove brain tumours could be easier and safer for patients due to the use of guiding surgery with lasers. Or even the diagnosis of bacterial meningitis could soon be made quicker due to the development of a new test that makes use of lasers. 

Image Source: Death Star