Wednesday, 2 May 2012

Remote heating

Scientists have discovered that when electric current is run through carbon nanotubes, objects nearby heat up while the nanotubes themselves stay cool, like a toaster that burns bread without getting hot. Understanding this phenomenon could lead to new ways of building computer processors that can run at higher speeds without overheating, dissipating their heat elsewhere.

It seems like an ordinary morning at first, but when you go to the kitchen for breakfast, something is wrong. Your toast is burned but the toaster is cold. The switch on the stove is set to "HI" and the teapot is whistling, but the burner isn't hot. As you check your e-mail on your laptop, the surface of the kitchen table it sits on gets warmer and warmer, but the computer isn't overheating--in fact, it's cool to the touch.

In an electron microscopy facility at the A. James Clark School of Engineering at the University of Maryland, Kamal Baloch and John Cumings were having exactly that kind of morning. They ran their experiments over and over, and the result was always the same: when they passed an electrical current through a carbon nanotube, the substrate below it grew hot enough to melt metal nanoparticles on its surface, but the nanotube itself seemed to stay cool, and so did the metal contacts attached to it.

This might not seem so strange at first glance--after all, food cooked in a microwave oven gets hot while the oven itself stays close to room temperature. The problem is that Baloch and Cumings weren't intentionally generating a microwave field. They were only passing a direct electrical current through the nanotube, which should have caused it to heat up. The data were telling them a story that didn't seem to make any sense--one about a plugged-in toaster that could burn bread without getting hot.

No comments:

Post a Comment