Albert Abraham Michelson Biography

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World of Scientific Discovery on Albert Abraham Michelson

Born in Strelno, Prussia (now Strzelno, Poland), Michelson and his family moved to the United States in 1854, settling in California during the gold rush. While his father worked as a supplier for miners, Michelson attended high school in San Francisco.

Displaying an aptitude for science, Michelson applied to the United States Naval Academy in Annapolis, Maryland. Although he was initially rejected, Michelson journeyed to Washington, D.C., to appeal his case and, with a letter from his congressman in hand, went directly to President Ulysses S. Grant. Impressed with Michelson's tenacity, Grant arranged for his admittance to the Academy.

While showing little promise as a seaman, Michelson demonstrated an uncanny skill with precision instruments. After graduating in 1873, he was offered a position teaching physics and chemistry at the Naval Academy. Michelson focused his research on the nature of light. He was particularly interested in measuring the speed of light, a feat that Jéan Foucault had accomplished a few years earlier, but one which Michelson felt sure he could perform more accurately.

Funded with $2000 of his father-in-law's money, he improved upon Foucault's equipment and published his findings in 1879. Though his experiments gained him some recognition, he was by no means done with his investigation. His curiosity about the velocity of light had become an obsession, and he soon charted a path of research that would dominate the rest of his career.

Michelson devoted most of his energy toward attempting to prove the existence of ether, an invisible substance that many felt comprised space and through which the planets and light were thought to travel. Scientists who subscribed to the ether-drift theory claimed that light was an undulation, and that ether was the medium that carried it (much like waves in water). Michelson hypothesized that he could prove the existence of an ether wind by comparing the speed of two beams of light, one traveling across the direction of the ether wind's flow, one traveling against the ether. As the device generating the beams was rotated, both beams could successively be made to travel against the ether, and the variationsin velocity could be recorded, thus proving the existence of the ether. In order to conduct his experiment, Michelson constructed a device called an interferential refractometer that generated a beam of light and split it into the two perpendicular beams necessary for comparison.

The first ether-drift experiment, conducted in Berlin in 1881, produced absolutely no evidence of an ether wind. Though Michelson dubbed the experiment a failure, he remained convinced of the existence of ether. Realizing that his new device was unsurpassed in sensitivity and versatility, he spent the next few years perfecting the design. In 1887, after accepting a position at the Case School of Applied Science in Cleveland, Ohio, Michelson began to collaborate with Edward Morley of nearby Western Reserve College. The two redesigned the 1881 experiment using Michelson's newly constructed interferometer, which was many times more precise than his earlier apparatus. Over the course of five days in July, they conducted the now-famous Michelson-Morley experiment. The result of their exhausting research was, again, a complete lack of evidence that would support the ether theory.

Though the Michelson-Morley Experiment seemed fruitless at the time, it resulted in two major scientific advances. First, the experiment virtually disproved the old ether theory. Scientists who had once leaned toward an acceptance of this concept were now forced to re-examine their beliefs. New hypotheses were posed by such physicists as Hendrik Lorentz, forming the foundation upon which Albert Einstein postulated his special theory of relativity in 1905. Second, Michelson began searching for new applications for his interferometer. The device, he noted, could be used to record interference patterns of light, patterns that took the form of interference fringes on a photographic plate. Using the fringes of red cadmium light, Michelson measured the length of a meter in terms of wavelengths of light, paving the way for the use of wavelength as an international standard for measuring length. Michelson continued to conduct research using his interferometer throughout his life.

While in southern California, he applied his expertise to the field of astronomy, measuring the diameter of objects such as asteroids and small moons, and in 1920 he measured the diameter of the distant star Betelgeuse in the constellation Orion. In later years, he attempted, once again, to determine the precise speed of light. He conducted a number of experiments in the California mountains, measuring the time it took light to cross from one peak to another. The figure he derived--186,271 miles (17,699 km) per second--is within 11 miles (17 km) per second of today's best estimate. Though he never received a doctoral degree, Michelson was the first American recipient of the Nobel Prize for physics, which he received in 1907, and garnered a total of eleven major scientific honors.