To be sure, the gadget had pluses. Not only could the transistor amplify electric current like a vacuum tube, it also used little power, didn't need to warm up, and was compact—a thimble-sized cylinder with a couple of protruding wires. But because its main ingredient was an expensive, hard-to-handle element called germanium, the transistor seemed likely to remain a laboratory curiosity.

What happened instead was total technological conquest. Scientists and engineers learned how to make it from abundant silicon, shrink it to microscopic size, and harness it for once-unimaginable powers of digital computing, control, communication, detection, and display. As costs plunged and performance soared, transistor-based circuits found their way into thermostats and sewing machines, power tools, children's toys and greeting cards, cameras and cell phones, fax machines and industrial robots, tractors and missiles. Home, office, factory, farm, and practically every other venue of human activity, within a few decades, became a kind of vast ecosystem of transistorized electronics.

The roots of the triumph reach deep. Germanium and silicon, along with a number of other crystalline materials, are semiconductors, so-called because they neither conduct electricity well, like most metals, nor block it effectively, as do insulators such as glass or rubber. Back in 1874 a German scientist named Ferdinand Braun identified a surprising trait of these on-the-fence substances: Current tends to flow through a semicon-ductor crystal in only one direction. This phenomenon, called rectification, soon proved valuable in wireless telegraphy, the first form of radio communication.

When electromagnetic radio waves traveling through the atmosphere strike an aerial, they generate an alternating (two-way) electric current. However, earphones or a speaker must be powered by direct (one-way) current. Methods for making the conversion, or rectification, in wireless receivers existed in the closing years of the 19th century, but they were crude. In 1899 Braun patented a superior detector consisting of a semiconductor crystal touched by a single metal wire, affectionately called a "cat's whisker." His device was popular with radio hobbyists for decades, but it was erratic and required much trial-and-error adjustment.