The defining event of young Nikola’s childhood was the day he witnessed the death of his older brother Dane in a riding accident. In the years following the tragedy, Tesla (the son and grandson of Serbian Orthodox priests) began seeing visions of the air around him “filled with tongues of living flame.” As an adolescent Tesla learned to exercise his willpower to control the visions, but in later life he would spend much of his time feeding and, he claimed, mystically communicating with New York City’s pigeons.

After graduating from university, Tesla worked for Edison’s electric company in Paris, but traveled to the United States in 1884 in the hopes of working directly for Edison, the leading figure in the race to deliver electric lighting and power to consumers. Tesla quickly gained a job as an engineer at Edison’s headquarters, impressing the “Wizard of Menlo Park” with his hardworking ingenuity. After Edison casually mentioned that he would pay $50,000 for an improved direct current (DC) generator design, Tesla worked nights until he came up with a solution. Edison refused to pay up, claiming he had been joking. Soon after, Tesla quit to form his own electric company. While he searched for backers to support his research into alternating current, Tesla took a job digging ditches for $2 a day to make ends meet.

Twain and Tesla became friends in the 1890s, thanks in part to Twain’s lifelong fascination with technology and new inventions. Visiting Tesla’s lab late one night, Twain posed for one of the first photographs to be lit by incandescent light. In 1895, Tesla and photographer Edward Ringwood Hewett invited Twain back to the lab to pose for another photo, this one lit using an electrical device called a Crookes tube. When Tesla reviewed the resulting photographic negative, he found it splotchy and spotted and decided it was ruined. It was only weeks later, after German scientist Wilhelm Röntigen announced his discovery of what he called “X-radiation” produced by Crookes tubes, that Tesla realized the photograph of Twain had been ruined by the X-ray shadows of the camera’s metal screws.

At the height of the Spanish-American War in 1898, one of Tesla’s side projects was a miniature boat that could be started, stopped and steered with rudimentary radio signals. When he filed a patent for the device, the U.S. Patent Office refused to believe that it could work, and so dispatched an agent to Tesla’s Manhattan lab for a demonstration. Tesla also showed his boat to a string of other important visitors, including J.P. Morgan and William K. Vanderbilt. He told the New York Post that his invention, which would allow battles to be fought without putting humans at risk, would render warfare itself obsolete. “Battle ships will cease to be built,” he predicted, “and the most tremendous artillery afloat will be of no more use than so much scrap iron.”

During the summer of 1899 Tesla set up a field laboratory in Colorado Springs, Colorado, to the possibilities of using high-altitude stations to transmit information and electric power over long distances. One July day, while tracking lightning storms, Tesla’s equipment picked up a series of beeps. After ruling out solar and terrestrial causes, he concluded that the signals must be from another planet. The following Christmas, in response to the American Red Cross’s request for a prediction of the greatest scientific achievement of the coming century, Tesla wrote, “Brethren! We have a message from another world, unknown and remote. It reads: one… two… three…” In 1996 scientists published a study replicating Tesla’s experiment and showing that the signal was in fact caused by the moon Io passing through Jupiter’s magnetic field.

In 1901 Tesla convinced financier J.P. Morgan to invest $150,000 in a new venture—a powerful laboratory at Wardenclyffe, on the northern shore of Long Island, that would be the new center for Tesla’s work on long-distance radio and electric power transmission. Stanford White, the country’s leading architect and Tesla’s longtime friend, designed a single-story lab with classical proportions, backed by a giant, 185-foot tall tower. The tower, which could be seen as far away as New Haven, Connecticut, stood atop an elaborate grounding system Tesla designed to help his transmitter “get a grip on the earth so that the whole of this globe can quiver.” A shaft nearly as deep as the tower was tall linked the transmitter to a series of 16 underground horizontal steel pipes, each 300 feet in length.

When funds ran out before the Wardenclyffe tower could be completed, Tesla begged Morgan for additional funding, but was rebuffed. Although some biographers speculate that Morgan cut off funds once he realized that Tesla’s plan to provide wireless power was unlikely to be profitable, the key factor for Morgan was likely his concern about getting caught up in a rash of market speculation surrounding radio projects. In July of 1903, after a particularly blunt rejection arrived from Morgan, Tesla cranked up his equipment, sending lightning streaking from the Wardenclyffe tower until after midnight. A year later, after another heartfelt request for funding spurred a one-word answer from Morgan (“No”), Tesla wrote back accusing the pious Episcopalian Morgan of being a Muslim fanatic.

Although for decades he had been a part of New York’s high society, age and poverty left Tesla more and more isolated. He lived alone in a succession of ever-cheaper hotels and often preferred the company of pigeons to people. Nevertheless, he kept one element of his days as a renowned showman-inventor, in the form of popular press conferences he held every July 10 to celebrate his birthday. When he turned 79 he announced his invention of a pocket-sized oscillator that could destroy the Empire State Building. A year later he held forth on his secret for longevity: toe-wriggling.

The defunct lab at Wardenclyffe was eventually turned over to the owners of the Waldorf-Astoria in partial payments for Tesla’s debts. Decades later, the managers of the Governor Clinton hotel were given a similar piece of Tesla collateral: a wooden case the inventor said contained a working model of his potentially war-ending particle weapon. Tesla’s “death beam” (he was insistent that it was not, as the press reported, a “death ray”) would be able to stop any invading army, thus making warfare pointless. When he turned over the box containing the model, Tesla warned the hotel’s employees that they must never open it. They fearfully complied, hiding the box in a storeroom. After his death in 1943 the box was pried open and found to contain nothing but harmless old electrical components.