Tesla’s Other Obsession: The Experiments That Made His Colleagues Genuinely Scared

Nikola Tesla is one of those historical figures who has been so thoroughly absorbed by internet mythology that separating what he actually did from what people claim he did requires some effort. He was genuinely extraordinary. He was also, at various points in his career, running experiments that terrified his assistants, alarmed his neighbors, knocked out the power for half a city, and sent police officers to his door.

The Device He Could Fit in His Coat Pocket

In 1898, an earthquake shook a neighborhood in lower Manhattan. Police and ambulances responded. Buildings shook, windows cracked, people ran into the street. The cause was a machine the size of a large alarm clock, which Tesla had clamped to a steel pillar in his laboratory at 46 East Houston Street.

He described it himself years later in a quote I keep coming back to: “I was experimenting with vibrations. I had one of my machines going and I wanted to see if I could get it in tune with the vibration of the building. I put it up notch after notch. There was a peculiar cracking sound. I asked my assistants where the sound came from. They did not know. I put the machine up a few more notches. There was a louder cracking sound. I knew I was approaching the vibration of the steel building. I pushed the machine a little higher. Suddenly all the heavy machinery in the place was flying around. I grabbed a hammer and broke the machine. The building would have been about our ears in another few minutes.”

Police arrived to investigate the earthquake. By the time they reached his lab, Tesla had already smashed the device with a hammer. He reportedly greeted them with: “Gentlemen, I am sorry. You are just a trifle too late to witness my experiment.”

Colorado Springs and the Lightning That Knocked Out the City

In 1899, Tesla relocated to Colorado Springs with a small team of assistants to run high-voltage experiments he could not safely conduct in New York. His assistants were told they were working on wireless telegraphy. They were not fully informed about everything else Tesla had in mind.

He built the largest Tesla coil in history, nearly 50 feet in diameter. He used it to generate artificial lightning bolts over 130 feet long, producing thunder audible 15 miles away. Local residents reported electrified butterflies, sparks appearing on horses’ hooves, and flames jumping from water pipes and faucets. Ball lightning reportedly floated through the laboratory. One night, Tesla believed he had detected radio signals from outer space through his transmitter.

Then one evening he ran an experiment that overloaded the local power plant’s generator, blew out the transformer, and cut electricity to the entire city of Colorado Springs. The power company refused to restore his supply until he repaired the generator at his own expense.

His assistants, who had signed up for telegraphy research, were by this point experiencing something significantly beyond that.

The Plan to Transmit Power to the Entire Planet

What Tesla was actually trying to do in Colorado was not just generate lightning for its own sake. He had become convinced that the Earth itself could function as an electrical conductor. By understanding the planet’s resonant frequency and using the right equipment, he believed he could transmit electrical power wirelessly to any point on the globe.

This became Wardenclyffe Tower, the massive transmitter he built on Long Island from 1901 to 1906 with funding from J.P. Morgan. The plan was to broadcast electricity through the Earth and the upper atmosphere so that anyone, anywhere, could access power for free by simply sticking a rod in the ground.

Morgan pulled the funding when he asked Tesla how anyone would charge customers for electricity delivered this way and Tesla could not give him a satisfactory answer. The tower was eventually demolished for scrap during World War I. Tesla spent the rest of his life trying to revive the project and never succeeded.

The Teleforce Weapon He Called a Peace Ray

In his later years, from roughly the 1930s until his death in 1943, Tesla regularly announced to reporters that he had designed a weapon he called the teleforce device. He described a beam that could project a stream of charged particles in a straight line through the air, powerful enough to shoot down aircraft at 250 miles and stop an army in its tracks. He insisted it was a defensive weapon and that its existence would make war impossible because no country could attack without being annihilated first.

On top of that, he offered the plans to multiple governments, including the United States, the United Kingdom, Canada, and the Soviet Union. The Soviet Union reportedly paid him $25,000 for a portion of his research in 1935, though what they received and what they did with it remains genuinely unclear.

After Tesla died alone in his hotel room in January 1943, government agents went through his papers. The FBI was involved. The exact contents of those papers have never been fully disclosed. Whether the teleforce weapon was real science, wishful thinking, or something in between, the people who showed up to collect his notes clearly considered the question worth taking seriously.