"It takes a formidable amount of computing power to process visual scenes," says Furber. Kinect's party trick costs 12 watts. But something smart enough to get around on its own – say, as smart as a squirrel – might need 10,000 watts.
Squirrel-bot's power bill makes him impractical – not to mention the hefty power cord he'd have to drag around. But people are working on more efficient computers that could nudge technology in that direction.
"Reducing the power by a factor of 100 to 1,000 is not impossible," says Eric Pop, a nanotechnologist at the University of Illinois in Urbana-Champaign. "We don't know how to do it today, but it's not impossible."
Professor Pop is working on one possible approach: Fabricate chips with new materials that conduct electricity more effectively. Better conductivity means less electricity is converted into heat – so less is needed to power the chip.
One material, called graphene, consists of a sheet of carbon atoms connected in a hexagonal, chicken-wire pattern. Graphene transistors might consume a tenth to a hundredth the power that current transistors use.
Pop is also investigating a second option for building transistors, called carbon nanotubes, in which the carbon sheet is rolled into a tube a thousandth as wide as a red blood cell. He has built simple chips containing 100 to 1,000 graphene or nanotube transistors. He can induce the nanotubes to emit different wavelengths of light – suggesting that they could also form low-power computer screens or electronic billboards.