Transistor

In December 1947 John Bardeen, Walter Brattain, and William Shockley at Bell Labs demonstrate a transistor, a solid piece of semiconductor that switches and amplifies like a vacuum tube. The tube was glass, hot, large, and fragile. The transistor is small and, once manufactured well, reliable.

The contribution is a switch you can pack. A computer of tubes fills a room and fails often. A computer of transistors shrinks every generation. Radios, hearing aids, and then chips all depend on this. Without it, the microprocessor does not exist and a robot's controller stays a cabinet.

The 1947 device is a point-contact transistor, awkward to make. Shockley's junction transistor and later silicon planar manufacturing are what industry actually builds. The Nobel Prize in 1956 is for the effect, not for a finished product.

Bell Labs required a license that spread the invention. That licensing is part of why the transistor becomes an industry instead of a single company's secret.