As computer chips get smaller and faster, they become little electronic furnaces-and a lot of research goes into finding better ways to carry away the heat so the chip can do its work without melting. One new solution from the University of Pennsylvania: carbon nanotubes, each only one ten-thousandth the width of a human hair. Studied since their discovery in 1991 for their strength and electrical properties, nanotubes could be the world’s best heat conductors as well. Materials scientist John Fischer and physicist Alan Johnson measured the speed of sound waves traveling down the tubes as an indirect gauge of heat propagation and found it to be about 10,000 meters per second. Contrary to expectations, connections between tubes in a bundle did not slow the waves. This suggests that single tubes or bundles of aligned tubes could be used to carry heat away from computer chips.The University of Pennsylvania is seeking to license the application to device makers such as Advanced Micro Devices and Intel.