Nikola Tesla

By Lin Yue

Every time you flip a switch, you are using Nikola Tesla's invention. Born on July 10, 1856, in Smiljan, in what is now Croatia, Tesla was the prophet of alternating current — the form of electricity that won the war of currents and still flows through every grid on earth.

The insight struck him in 1882, while walking in a Budapest park reciting Goethe's Faust: a rotating magnetic field, generated by two alternating currents out of phase, could drive a motor with no commutator, no brushes, no sparking contacts — a motor with essentially one moving part. The induction motor was born in his head before it existed in metal. Working for Edison's company in New York in 1884, Tesla found Edison wedded to direct current and uninterested in his ideas; he quit, dug ditches for a time to survive, and in 1887 filed the patents for the polyphase AC system: generator, transformer, transmission line, motor — a complete architecture for generating electricity far from where it was used and delivering it at high voltage with minimal loss.

George Westinghouse bought the patents in 1888 and bet his company on them. The 1893 Chicago World's Fair — the "White City" blazing with a quarter-million Tesla-powered lamps — was AC's coming-out party. The decisive victory came at Niagara Falls: in 1895 the Adams power station began sending alternating current to Buffalo, twenty miles away, something Edison's direct current could never have done economically. Tesla's system, not Edison's, became the skeleton of the electric age.

The Tesla coil of 1891 — a resonant transformer producing spectacular high-frequency, high-voltage discharges — became the standard tool of early radio research and still lives in every plasma globe and spark-gap classroom demo. Tesla's later years were tragic: the Wardenclyffe tower on Long Island, his dream of wireless power transmission, collapsed for lack of funding; he died alone and nearly penniless in a New York hotel on January 7, 1943. But the grid outside his window ran on his patents. It still does.

The War of the Currents made Tesla famous and Westinghouse rich — and then nearly ruined them both. In the Panic of 1907, Westinghouse faced bankruptcy, strangled by the royalties owed on Tesla's AC patents, which would have made Tesla one of the richest men in the world. Legend holds that Tesla walked into Westinghouse's office and tore up the contract, freeing the company. The story is likely embellished, but the financial fact is real: Tesla surrendered a fortune and spent the rest of his life chasing the next miracle. There were genuine wonders along the way: in 1898 he demonstrated a radio-controlled boat at Madison Square Garden — the birth of remote control — and his high-frequency experiments laid groundwork for X-rays and radio. But the big bets failed. The Wardenclyffe Tower (1901–1906), funded briefly by J.P. Morgan, was meant to transmit power wirelessly around the globe; when Morgan realized there was no way to meter and bill it, the money stopped. Tesla spent his final decades in New York hotels, feeding pigeons in Bryant Park, filing patents nobody bought. In 1915 newspapers reported he would share the Nobel Prize with Edison; the prize never came. He died owing the Hotel New Yorker $3,000, and the FBI seized his papers the next day.

Impact on civilization

Tesla's polyphase system is the single most load-bearing invention of the industrial age. Direct current could light a neighborhood; only alternating current could electrify a continent. By making long-distance transmission economical, AC made giant power stations viable, which made cheap electricity abundant, which made the second industrial revolution possible: electric motors in factories, streetcars, subways, elevators — the entire twentieth-century city is a Tesla artifact. The induction motor, his other great gift, remains the workhorse of industry: billions of them run pumps, fans, compressors, and appliances worldwide, with the same basic geometry he sketched in 1882. Wireless research, radio, and eventually radar all passed through his high-frequency experiments. The modern world runs on alternating current because one man saw a rotating field in a Budapest park and refused to let it go.

Alternating current also made rural electrification possible: high-voltage lines could economically reach farms and villages that direct current could never have served, ending the isolation of country life in the twentieth century. The induction motor — cheap, rugged, brushless — became the invisible laborer of civilization, embedded by the billions in everything from refrigerator compressors to subway trains. When engineers in the 2020s design motors for electric cars, they still start from Tesla's rotating field.