A tractor beam, able to move real-life objects, has been developed at The Australian National University (ANU). Unlike the tractor beams on Star Trek, however, this one uses water, and was tested in a small tank.
Water is controlled by the device using wave generators. In laboratory experiments, developers found they could control the movement of both firm objects, as well as liquids like oil. These floating targets are able to move counter to the direction of wave travel.
"We have figured out a way of creating waves that can force a floating object to move against the direction of the wave. No one could have guessed this result," Horst Punzmann, of the Research School of Physics and Engineering, and head researcher on the project, said.
Ping-pong balls and other objects have been tested in the water tank. Investigators are able to move the target in the tank by controlling the frequency of waves striking the object.
Examination of the waves in the pool revealed that, under ideal conditions, they can create currents in water. Different plungers in the tank allowed researchers to create various patterns of flowing liquid.
"We found that above a certain height, these complex three-dimensional waves generate flow patterns on the surface of the water. The tractor beam is just one of the patterns, they can be inward flows, outward flows or vortices [whirlpools]," Michael Shats of ANU, and one of the lead researchers on the project, told the press.
This is the first time a device of its kind, with an action much like a science fiction tractor beam, has ever been developed.
In Star Trek, tractor beams are said to run on gravitons - the sub-atomic particles postulated to carry the force of gravity between bodies of matter. They are used not just in towing other vehicles and cargo, but have also been employed as makeshift weapons.
Oil spills could possibly be contained with this new-real world device, limiting damage from industrial spills and accidents. Objects floating in the water can also be moved by the new invention. The invention would need to be scaled up for use in real-life situations, and would be subject to natural waves and currents.
Study of the water tracking gun could provide researchers with information about how rip at beaches form.
Although the experiment itself was simple, the mathematics behind the finding remain a mystery.
"It's one of the great unresolved problems, yet anyone in the bathtub can reproduce it. We were very surprised no one had described it before," Punzmann said.