Tractor beams are not just for alien space ships. Scientists at the Australian National University have figured out how to create a tractor beam effect in water. Using wave generators, they were able to control “beams” of water and move a floating ping-pong ball in different directions.
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Their technique could be used on a larger scale to confine oil spills, manipulate floating ocean trash or other objects or explain rip tides at the beach.
“We have figured out a way of creating waves that can force a floating object to move against the direction of the wave,” project leader Horst Punzmann said in a press release. He and his team published their research in the latest issue of Nature Physics.
The wave generator is a horizontal device with little plungers on the underside that vibrate to create ripples on the water’s surface. Punzmann and his team showed that different shaped plungers created different swirling patterns on the water. Some plungers created inward flows, drawing the ping pong ball toward the wave generators, other plungers created outward flows, pushing the ball away.
Oddly, there is no mathematical theory to explain the movement produced in these experiments.
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“We realized that particle motion on the surface, determined by waves, is far too complex to handle by any existing theory,” Michael Shats, the paper’s senior author, told the BBC.
Credit: Australian National University