Even a simple electric current generates a magnetic field. An alternating current oscillating at a high voltage produces electromagnetic waves. Many inventors joined the race to make use of these waves, discovered by Heinrich Hertz in 1888, for wireless communication or other purposes.
Tesla was fascinated by high-frequency waves. Putting them to work, he was able to:
- Light lamps filled with neon gas. This new kind of lighting needed no glowing filament; the gas itself gave off the light.
- Cause vacuum tubes to glow from a distance, with no direct connection to the source of the waves.
- Heat a bar of metal to a very high temperature.
- Travel 50 miles (80 kilometers) to West Point, N.Y., and still detect waves generated in his New York City laboratory.
Many inventors contributed to the development of radio, but Guglielmo Marconi was awarded the Nobel Prize for the invention in 1909. Tesla resented the lack of recognition for his own fundamental and original contributions, which he had patented well before Marconi's first prototypes. In 1943, several months after Tesla's death, the U.S. Supreme Court finally recognized that Tesla's patented inventions were the basis of Marconi's initial achievement [source: PBS].
Tesla saw another use for the waves. He thought they would allow him to transmit electrical energy on a large scale without wires. He moved to Colorado Springs in 1898 and built large coils, now known as Tesla coils, which generated massive voltages. With them, he was able to generate man-made lightning. He lit 200 bulbs from a distance of 25 miles (40 km) and experimented with ways to send energy through the air or earth [source: Redshaw].
Returning to New York a year later, he convinced the banker J.P. Morgan to back him in a system that would create wireless communication around the world, allowing the broadcast of news, mail, even pictures. Tesla also continued to dream of transmitting electric power. He built a laboratory called Wardenclyffe on Long Island. There, he constructed a 187-foot-high (57-meters-high) wooden tower and drove steel pipes hundreds of feet into ground. As expenses mounted, Morgan backed out of the project. Deeply in debt, Tesla was forced to destroy the tower and abandon the laboratory in 1905. For the rest of his life, he remained convinced that wireless power transmission was feasible.
In the meantime, Tesla had used the electromagnetic waves to create a radio-controlled boat. He found that at very high voltages his homemade vacuum tubes gave off rays that could penetrate solid matter, and he was among the first to experiment with X-rays, creating what he called "shadowgraphs" [sources: Vujovic, Hrabak et al.]. Over time, Tesla's investigation of high-frequency waves formed the basis of innovations ranging from microwave ovens to cathode ray television picture tubes.
Tesla had taken his inventive genius in a different direction than contemporaries like Edison. His exploration of the unknown territory of high-frequency electricity and radio waves forged a path for many inventors who followed him.