The last thing two University of Toronto researchers want to hear is a Klingon joke. It seems to be the only point of reference lay people have when discussing their latest discovery: an invisibility cloak.

George Eleftheriades, an electrical and computer engineering professor, and his graduate student, Michael Selvanayagam, can hide a metal cylinder from radar detection, or make it appear bigger, smaller or even look like plastic.

The results of their work were published in the journal Physical Review X on Tuesday.

“We came up with a different way of cloaking,” an excited Eleftheriades said. “We can make things invisible or we can camouflage them. Let me explain.”

To understand how cloaking works, think about how radar works: When a radio wave is sent out and hits, say, a metal cylinder, it bounces off and a small part of the wave’s energy returns to its source, leaving a telltale signature of the object it has encountered.

In 2006, Duke University researchers discovered how to alter the way the radio wave behaves by using metamaterials — like a thick, glossy coating that bends waves.

Now think of that radio wave as being sent out and, rather than hitting the cylinder, flowing around it, like river water rushing by a tree stump. No bounce-back. No scatter. Like there’s nothing there.

“But to cloak a tank with metamaterials, the shell covering the tank would be almost as big as the tank,” Eleftheriades said in his lab, which looks more like a large dorm room with old machinery and bright lights.

So the student and the professor took a different approach. They covered the cylinder with antennae that cancel out incoming radio waves.

“It’s a similar concept to noise-cancelling headphones that send out sound waves to cancel out incoming sound waves,” Selvanayagam said.

Of course, that was only theoretical.

They had to demonstrate their invisibility cloak. So, like any good student, Selvanayagam built one out of odds and ends for only $2,000. The researchers set up their apparatus, about the size of a pool table, and lovingly dubbed it “the active cloak machine.”

In the centre is a metal cylinder similar in size and shape to a deep-dish pizza. Around its outer circumference are 12 antennae, attached using Styrofoam and masking tape.

A gaggle of wires powers the beast and records its results.

When radio waves are fired at the cylinder, the antennae fire waves back, essentially nullifying the waves.

What do the results show? Nothing. Like there’s nothing there.

The duo’s research has potential military applications, which they believe aren’t far from reality. The antennas they used are old technology. There are nanoantennas, Selvanayagam said, that could fit into a slim, flat or malleable sleeve that could be used to simply cover an object.

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A true invisibility cloak isn’t far off. Rather than employing radio antennas to counter radio waves, there are optical antennas that can hide infrared — as in heat — patterns, following a similar concept.

“But I wouldn’t call it invisibility; it would be more like a chameleon, adapting to whatever is around you so you can hide in plain sight,” Selvanayagam said.

“The only thing holding us back is money,” Eleftheriades gazing upon their metal, wire and Styrofoam masterpiece.