How will this work in an unfixed domain? A domain with no walls, as some of their visualisations seem to use the walls to generate the field.

I thought rip currents (known popularly as rip "tides") were pretty well understood, and it has nothing to do with this "tractor beam" effect: http://en.wikipedia.org/wiki/Rip_current

Great, now do the same trick with sound pressure waves in air!

That's been done too! (different lab) https://www.youtube.com/watch?v=odJxJRAxdFU

What about gravity waves in spacetime? Now you're getting into star trek technology.

I bet that would make a deep rhythmic noise as it operated.

The key thing about this is that objects can be pulled towards the device, rather than pushed away.

So, uhm, where is the beam?

Url changed from http://www.engadget.com/2014/08/11/tractor-beam-for-water/, which points to this.

The new URL doesn't work though. Looking to find the typo.

Ah here it is: http://www.anu.edu/vision/videos/12091/

(no edu.au at the end)

Weird; that one worked for me. However, the other one works too, so I changed it. Thanks!