Transistor
The tiny solid-state switch invented at Bell Labs in 1947 that replaced the vacuum tube and became the building block of all electronics.
On December 16, 1947, two physicists at Bell Laboratories in New Jersey pressed a pair of gold contacts onto a sliver of germanium and watched a faint electrical signal come out about a hundred times stronger than it went in. John Bardeen and Walter Brattain had built the first working transistor. A week later they demonstrated it to their supervisors, one of whom called it a magnificent Christmas present. It was arguably the most important invention of the twentieth century, and almost no one outside the lab noticed at the time.
A switch with no moving parts
The device the transistor replaced was the vacuum tube. Tubes could amplify a signal or switch a current, but they were fragile glass bottles that ran hot, burned out like light bulbs, and guzzled power. The early computer ENIAC used about 18,000 of them, filled a room, and needed constant repair as tubes failed.
A transistor does the same jobs, amplify and switch, using a solid piece of semiconductor and no moving parts at all. Apply a small voltage to a control terminal, and it governs a much larger current flowing through the device, the way a tap controls a flow of water. That is the whole trick: a tiny signal steering a big one, or a switch snapping cleanly between on and off, which is all a computer needs to store the ones and zeros of binary. William Shockley, who led the group and was furious at being left off the first patent, soon devised a sturdier design, and the three men shared the 1956 Nobel Prize in Physics.
From one to billions
The transistor's real power was that it could be shrunk, mass-produced for pennies, and wired together. Within a decade engineers learned to etch many transistors onto one slab of silicon, the integrated circuit. Then thousands, then millions, then billions, combined into the microprocessor. A modern smartphone holds well over ten billion transistors and far more computing power than all the machines that guided Apollo to the Moon.
Geography followed the technology. In 1956 Shockley left Bell Labs and moved to Mountain View, California, near where he grew up, to start his own company. His abrasive management backfired: eight of his most talented recruits, among them Gordon Moore and Robert Noyce, quit in 1957 to found Fairchild Semiconductor, whose offspring seeded Intel, AMD, and much of the region. Shockley was a brilliant physicist who later disgraced himself promoting racist theories, but by planting the transistor in a valley of apricot orchards, he accidentally gave the place its future name: silicon.
Every object with a chip inside it, every phone, car, pacemaker, satellite, and guided missile, traces back to that winter afternoon when a signal came out of a lump of germanium louder than it went in.