Scientists create a "water tractor beam"

Scientists create a "water tra...
Dr. Horst Punzmann and team leader Prof. Michael Shats, at the ANU wave tank
Dr. Horst Punzmann and team leader Prof. Michael Shats, at the ANU wave tank
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Dr. Horst Punzmann and team leader Prof. Michael Shats, at the ANU wave tank
Dr. Horst Punzmann and team leader Prof. Michael Shats, at the ANU wave tank

If you've ever tried to retrieve an object that's floating away in a lake or the ocean, then you'll know how frustrating it can be, trying to draw that item towards you. According to research recently conducted at The Australian National University (ANU), however, it's possible to move such objects in whichever direction you wish – as long as you can generate the right type of waves.

The research team experimented with a table tennis ball floating in a wave tank. By precisely manipulating the size and frequency of three-dimensional waves created by a wave generator, they were able to keep the ball in place, move it away from the generator, or even towards it – in the case of the latter, the ball was actually moving against the waves that were traveling out from the generator.

Although the scientists did establish that the waves generate flow patterns along the surface layer of the water, the actual mathematics behind the phenomenon are still not understood. "It's one of the great unresolved problems, yet anyone in the bathtub can reproduce it," said project leader Dr. Horst Punzmann. "We were very surprised no one had described it before."

It is hoped that if scaled up, their findings could be used in applications such as containing oil spills, retrieving drifting watercraft, or better understanding rip tides, in which swimmers are drawn away from the shore even though the waves are moving towards it.

A paper on the research was published today in the journal Nature Physics. The wave tank experiments can be seen in the video below.

Source: Australian National University

ANU Scientists create a Tractor Beam on water

Michael Erickson
I wonder if it is possible to generate gravitational waves and if so to effect movement of objects in space. There is a lot to explore in gravitation theory.
If they can do it reliably "in the wild" the applications for containing oil spills are obvious and exciting.
After many years of boating, I have never ceased to be amazed at all the different types of waves I have encountered. What is even more amazing is that many types of waves are usually present at the same time traveling in different directions. Their constructive and destructive interference often leads to very interesting effects ranging from nearly flat water one minute to enormous waves that suddenly appear and then disappear. Broad and rolling six foot waves on the ocean are so gentle compared to vicious six foot white caps on the Great Lakes that pound like a jackhammer. Even the shapes of the waves vary dramatically according to wind, current and water depth. They can even be reflected or deflected by solid objects. This article is interesting since I had often seen floating objects in the water moving opposite to the wind and waves. I usually thought it was the current or just an optical illusion. This is an interesting study but I suspect that effectively using this technology in the wild will be like listening to a violin at a shooting range.