(*10th july 1856 ; + 7th january 1943)

was an inventor and a mechanical and electrical engineer. He is often cited as one of the most important contributors to the birth of commercial electricity and is well known for many revolutionary developments in the field of electromagnetism. Tesla's patents and theoretical work formed the basis of modern alternating current (AC) electric power systems, including the polyphase system of electrical distribution and the AC motor.

He was born an ethnic Serb in the village of Smiljan, Croatian Military Frontier, in the territory of today's Croatia, and later became an American citizen. Much of his early work pioneered modern electrical engineering and most of his discoveries were of groundbreaking importance. During his years in the USA, Tesla's fame rivaled that of any other inventor or scientist in history, but because of his eccentric personality and his seemingly unbelievable statements about possible scientific and technological developments, Tesla was ostracized and considered a mad man. The unit measuring magnetic field B (the tesla), was named after him, as well as the Tesla effect of wireless energy transfer to wirelessly power electronic devices which Tesla demonstrated on a low scale with incandescent light bulbs.

Aside from his work on electromagnetism and electromechanical engineering, Tesla contributed in varying degrees to the establishment of robotics, remote control, radar and computer science, and to the expansion of ballistics, nuclear physics, and theoretical physics. In 1943, the Supreme Court of the United States credited him as being the inventor of the radio.

Early years

Tesla was born to Serbian parents in the village of Smiljan, Austrian Empire near the town of Gospić, found in the territory of modern day Croatia. He was the fourth of five children. Tesla later studied electrical engineering at the Austrian Polytechnic in Graz. During that time he studied the uses of alternating current. Some sources say he received Baccalaureate degrees from the university at Graz. However, the university claims that he did not receive a degree and did not continue beyond the first semester of his third year. In December 1878 he left Graz and broke all relations with his family. His friends thought that he had drowned in Mura. He went to Maribor, where he was first employed as an assistant engineer for a year. He suffered a nervous breakdown during this time. Tesla engaged in reading many works, memorizing complete books, supposedly having a photographic memory. Tesla related in his autobiography that he experienced detailed moments of inspiration. He suffered a peculiar affliction in which blinding flashes of light would appear before his eyes, often accompanied by hallucinations. Much of the time the visions were linked to a word or idea he might have come across; just by hearing the name of an item, he would involuntarily envision it in realistic detail.

United States and France

In 1882 he moved to Paris, France, to work as an engineer for the Continental Edison Company, designing improvements to electric equipment brought overseas from Edison's ideas. In the same year, Tesla conceived the induction motor and began developing various devices that use rotating magnetic fields for which he received patents in 1888. On 6 June 1884, Tesla first arrived in the US in New York City with little besides a letter of recommendation from Charles Batchelor. In the letter to Thomas Edison, Batchelor wrote, "I know two great men and you are one of them; the other is this young man." Edison hired Tesla to work for his Edison Machine Works. Tesla's work for Edison began with simple electrical engineering and quickly progressed to solving some of the company's most difficult problems.

In 1886, Tesla founded his own company, Tesla Electric Light & Manufacturing. The initial financial investors disagreed with Tesla on his plan for an alternating current motor and eventually relieved him of his duties at the company. Tesla worked in New York as a common laborer from 1886 to 1887 to survive and raise money for his next project. In 1887, he constructed the initial brushless alternating current induction motor, which he demonstrated to the American Institute of Electrical Engineers in 1888. In the same year, he developed the principles of his Tesla coil and began working with George Westinghouse at Westinghouse Electric & Manufacturing Company's Pittsburgh labs. Westinghouse listened to his ideas for polyphase systems which would allow transmission of alternating current electricity over long distances.

In April 1887, Tesla began investigating X rays using his own single terminal vacuum tubes. This device differed from other early X-ray tubes in that it had no target electrode. The modern term for the phenomenon produced by this device is bremsstrahlung (or braking radiation). We now know that this device operated by emitting electrons from the single electrode through a combination of field electron emission and thermionic emission. Once liberated, electrons are strongly repelled by the high electric field near the electrode during negative voltage peaks from the oscillating HV output of the Tesla Coil, generating X rays as they collide with the glass envelope. By 1892, Tesla became aware of the skin damage that Wilhelm Röntgen later identified as an effect of X rays.

Tesla demonstrated "the transmission of electrical energy without wires" depending upon electrical conductivity as early as 1891. The Tesla effect is a term for an application of this type of electrical conduction (that is, the movement of energy through space and matter). On 30 July 1891 at the age of 35, he became a citizen of the United States. Tesla established his 35 South Fifth Avenue laboratory in New York during this same year.

At the 1893 World's Fair, the World's Columbian Exposition in Chicago, an international exposition was held which for the first time devoted a building to electrical exhibits. It was a historic event as Tesla and George Westinghouse introduced visitors to AC power by using it to illuminate the Exposition. On display were Tesla's fluorescent lamps and single node bulbs. Tesla also explained the principles of the rotating magnetic field and induction motor by demonstrating how to make an egg made of copper stand on end in his demonstration of the device he constructed known as the "Egg of Columbus".

At the age of 41, he filed the first basic radio patent. A year later, he demonstrated a radio-controlled boat to the US military, believing that the military would want things such as radio-controlled torpedoes. Tesla had developed the "Art of Telautomatics", a form of robotics, as well as the technology of remote control. In 1898, he demonstrated a radio-controlled boat to the public during an electrical exhibition at Madison Square Garden. This device had an innovative coherer and a series of electronic logic gates. In 1899, Tesla moved and started research in Colorado Springs, Colorado, where he had enough room for his high-voltage, high-frequency experiments. Upon his arrival he told reporters that he was conducting wireless telegraphy experiments transmitting signals from Pikes Peak to Paris. Tesla's diary contains explanations of his experiments concerning the ionosphere and the ground's telluric currents via transverse waves and longitudinal waves. At his lab, Tesla proved that the earth was a conductor, and he produced artificial lightning. Tesla also investigated atmospheric electricity, observing lightning signals via his receivers. Reproductions of Tesla's receivers and coherer circuits show an unpredicted level of complexity. Tesla researched ways to transmit power and energy wirelessly over long distances. He transmitted extremely low frequencies through the ground as well as between the Earth's surface and the Kennelly–Heaviside layer. He received patents on wireless transceivers that developed standing waves by this method. In his experiments, he made mathematical calculations and computations based on his experiments and discovered that the resonant frequency of the Earth was approximately 8 Hertz (Hz). In the 1950s, researchers confirmed that the resonant frequency of the Earth's ionospheric cavity was in this range.

In the Colorado Springs lab, Tesla observed unusual signals that he later thought may have been evidence of extraterrestrial radio communications coming from Venus or Mars. He noticed repetitive signals from his receiver which were substantially different from the signals he had noted from storms and earth noise. Specifically, he later recalled that the signals appeared in groups of one, two, three, and four clicks together. Tesla had mentioned before this event and many times after that he thought his inventions could be used to talk with other planets. There have even been claims that he invented a "Teslascope" for just such a purpose. It is debatable what type of signals Tesla received or whether he picked up anything at all. Research has suggested that Tesla may have had a misunderstanding of the new technology he was working with, or that the signals Tesla observed may have simply been an observation of a non-terrestrial natural radio source such as the Jovian plasma torus signals.

Later years

In 1900, with US$150,000, Tesla began planning the Wardenclyffe Tower facility. The tower was finally dismantled for scrap during World War I. Newspapers of the time labeled Wardenclyffe "Tesla's million-dollar folly". In 1904, the US Patent Office reversed its decision and awarded Guglielmo Marconi the patent for radio, and Tesla began his fight to re-acquire the radio patent. On his 50th birthday in 1906, Tesla demonstrated his 200 hp (150 kW) 16,000 rpm bladeless turbine. On Tesla's seventy-fifth birthday in 1931, Time magazine put him on its cover. The cover caption noted his contribution to electrical power generation. Tesla received his last patent in 1928 for an apparatus for aerial transportation which was the first instance of VTOL aircraft.