Are invisibility cloaks finally here?

 Nathan Landy, a Duke University graduate student, displays an experimental cloaking device that's being developed at Duke.

What in the name of Harry Potter is David Smith up to? It’s not possible to cloak things the way Harry does in some of his adventures, right? Making something invisible would defy the laws of science.

Well, maybe not.

Smith, who earned a doctorate in physics at the University of California San Diego, is a professor at Duke University, where he’s stirring attention with his efforts to cloak things with the use of common materials. Smith doesn’t make objects literally disappear. But the materials effectively make small things invisible to microwave energy.

It’s trippy research that Smith will discuss on Wednesday, February 27, during a free public lecture at UC San Diego. He’ll take to the podium at the Great Hall in the International House at 7 p.m., and explain how cloaking works and explore how it might be used to improve our lives. He gave us a preview of his talk during a recent phone call.

Q: Many people think of Harry Potter’s fictional invisibility cloak when the subject of invisibility comes up. Is this the kind of thing you’re working on?

A: Harry Potter’s magical cloak can seemingly make someone completely invisible to detection, whether they’re sitting still or moving around. We’re not trying to make people invisible. But we are working on a closely related concept that could help make things like your cellphone and certain electronic systems in automobiles work better and more reliably.

Our experiment involves microwaves, an electromagnetic form of energy. Humans can’t see microwaves, but they’re there and they can get blocked by objects. For example, if you’re sitting in an airport trying to use your cellphone your wireless signal might get blocked by the big column that helps hold up the roof of the terminal. That could disrupt your call, or it could make it hard to do something like call up Netflix on the Internet. We’re working on ways to make that column ‘invisible’ to microwaves. We do that by bending the microwaves around blockages.

Q: How do you do that?

A: We cloak objects with meta-materials. These materials cause the microwaves to go around objects. Think of water flowing in a stream. The water flows around things like rocks. In a similar way, microwaves go around things that would block their movement.

Q: And what are meta-materials?

A: They’re basically copper circuits that are placed on things like plastic and Teflon. The copper can be arranged in a pattern that causes microwaves to refract. We want to use meta-materials to cloak things that can become an obstruction. This is becoming increasingly important with things like automobiles because they’re taking on more and more electronic systems, from wireless Internet to collision-avoidance sensors. We might be able to cloak the grill on a car to prevent it from blocking the signals that come from the collision-avoidance system.

Q: It sounds like this would have a lot of applications for the military. Does it?

A: Yes. The military uses a lot of antennas and they are putting more and more of them together in smaller spaces. We might be able to cloak one antenna to prevent it from blocking the signal of another.


