When Anwar Ghuloum came to work at Intel in 2002, the company was supreme among chip makers, mainly because it was delivering processors that ran at higher and higher speeds. "We were already at three gigahertz with Pentium 4, and the road map called for future clock speeds of 10 gigahertz and beyond," recalls Ghuloum, who has a PhD from Carnegie Mellon and is now one of the company's principal engineers. In that same year, at Intel's developer conference, chief technology officer Pat Gelsinger said, "We're on track, by 2010, for 30-gigahertz devices, 10 nanometers or less, delivering a tera-instruction of performance." That's one trillion computer instructions per second.

But Gelsinger was wrong. Intel and its competitors are still making processors that top out at less than four gigahertz, and something around five gigahertz has come to be seen, at least for now, as the maximum feasible speed for silicon technology.