Harry Potter's Invisibility Cloak: Mirage Effect Created in Lab

Oct. 5, 2011 — -- It's hard to write about the experiment done at the University of Texas at Dallas without invoking Harry Potter and his invisibility cloak — but after you look at the video above, you'll probably agree it's 1) mesmerizing and 2) more realistic than the movie.

It's not a special effect. It's an experiment in photothermal deflection ("the mirage effect" to physicists), and it was done with nanotechnology.

If you're not into nanotechnology, read on anyhow. This isn't that complicated, at least in concept.

You know how, if you're driving down a highway in Florida or Arizona on a sunny summer day, the road far ahead can look wet as it shimmers in the heat? That mirage is created by photothermal deflection — the heat is bending the light rays, creating the impression that there's a puddle up ahead.

Pretty weird, but it's a natural effect — and you can't exactly turn it on or off.

In the lab, Ali Aliev and his colleagues did nature one better. They took carbon nanotubes — cylindrical molecules with a remarkable ability to conduct heat — and warmed them electrically. In a container of water, they were able to bend the light around them, making the sheet of material "disappear." By turning the heat on and off, they could make the sheet reappear … and disappear … and reappear … and disappear again.

Take that, Harry. Your cloak was invisible all the time.

They say life imitates art, and in this case, science does too. Reporting in the journal Nanotechnology, Aliev and his co-authors say, "The remarkable performance of nanotube sheets suggests possible applications as photo-deflectors and for switchable invisibility cloaks."

(Citation for the academically-inclined: Aliev A et al 2011 Nanotech. 22 435704.)