By pushing into a new dimension, engineers at IBM have nearly doubled the number of transistors they can fit on a microchip—the sort of device that animates your computer—cramming nearly 100 billion of them into a square centimeter. Announced yesterday, the advance continues a historic but slowing trend known as Moore’s Law that since the 1960s has seen the number of transistors on a chip double roughly every 2 years. But it underscores how engineers can no longer simply shrink transistors. To realize the increase, IBM researchers stacked them.