- Video report by ITV News Science Editor Tom Clarke
It's not physics. It's magic.
Or at least, that's what you can't avoid thinking when you first walk up to the Multimodal Acoustic Trap Display in the corner of a lab at the University of Sussex.
Switch on the darkened box and a polystyrene bead instantly levitates in mid air and hovers as static as if it's glued in place. Gesture with your finger and it follows you around. Another gesture and the bead oscillates so rapidly that LED light bouncing off it produces a 3D hologram-like image floating in space.
A crudely drawn but very "real" butterfly flaps in front of my nose. I can reach around it even cup it in my hands -- provided I leave enough of a gap to let the sound waves get through.
"It's not magic, it's ultrasound," insists its co-inventor Dr Diego Martinez Plasencia.
A bank of tiny speakers above and below the bead blast it with ultrasonic sound waves. We can't hear them, but they are powerful enough to levitate and then manipulate the bead or other lightweight objects like droplets of liquid.
Controlled in real time by computer these "ultrasonic tweezers" could form the basis of new 3D displays for home entertainment or advertising but also manipulate reactive liquids or even human tissues for laser-like precision without a human physically touching any or the objects.
There have been many advances in virtual reality, holograms and 3D displays since Star Wars' Princess Leia first floated onto our screens in hologram form in 1977 begging the last of the Jedi's for help.
But this latest research published in the journal Nature claims to be the first where a 3D or "volumetric" display can respond to touch and produce sound.
And the "touch" element is really neat. Because the bead which creates the display is held aloft by ultrasonic waves, they can be concentrated in space to create the feel of a virtual button.
Tap it, and the display changes.
It's a bit hit and miss, but the concept opens up a range of interactive possibilities that were, not that long ago, the stuff of Sci-Fi