There is no shortage of technologies proposed to eventually replace silicon, from ways to use complex organic molecules as transistors to "quantum computing" (see "Beyond Silicon," TR May/June 2000). But carbon nanotubes are emerging as a leading candidate. Not only are they the right size, with the right electronic properties, but their compatibility with existing semiconducting materials raises the prospect that, over the next decade, it may be possible to gradually integrate them with conventional silicon technology. That could give nanotubes the inside track, since most chip makers are no more anxious than Rueckes to overthrow existing manufacturing techniques.