In the 1940s electronics ran on vacuum tubes. Tubes were bulky, hot, fragile and power-hungry; a radio held a handful, a computer thousands — and one was always about to burn out. The ENIAC computer used 17,468 tubes and required roughly one replacement every day.

At Bell Telephone Laboratories in New Jersey, the physicist William Shockley led a postwar semiconductor research group. John Bardeen and Walter Brattain handled the experimental work. On 16 December 1947, two gold contacts arranged like the prongs of a fork on top of a germanium crystal amplified a small input signal roughly a hundredfold — the first "point-contact transistor" had worked. A formal demonstration to management took place on 23 December. The name was coined in early 1948: "transfer-resistor" → "transistor."

Within weeks Shockley designed the more robust and manufacturable "junction transistor." The three shared the 1956 Nobel Prize in Physics. The same year Shockley moved to California and founded his own company; the eight engineers who later left him (the "traitorous eight") went on to found Fairchild Semiconductor, then Intel, then Silicon Valley itself. A single invention reshaped an entire geography.

The first transistor fit in a hand. A modern computer chip holds hundreds of billions of transistors at sizes around 5 nanometres — smaller than a virus. Moore's Law predicted a doubling of transistor count every two years for decades; the engine of that law first ran on a single day at Bell Labs in December 1947. Smartphones, the internet, artificial intelligence, satellites, modern medical devices — all rest on that small piece of germanium that filled the gap left by the vacuum tube.