ANU has just posted this rather enlightening video showing off their ability to manipulate objects on water at a distance.

Physicists at The Australian National University (ANU) have created a tractor beam on water, providing a radical new technique that could confine oil spills, manipulate floating objects or explain rips at the beach.

The team, led by Dr Horst Punzmann, discovered they can control water flow patterns with simple wave generators, enabling them to move floating objects at will.
The team also experimented with different shaped plungers to generate different swirling flow patterns.

The surprisingly simple technique gives scientists a way of controlling things adrift on water in a way they have never had before, resembling sci-fi tractor beams that draw in objects.

Using a ping-pong ball in a wave tank, the group worked out the size and frequency of the waves required to move the ball in whichever direction they want.

Advanced particle tracking tools revealed that the waves do not push the ball along.