Einstein Albert

Albert Einstein Magnificent Scientific Letter in English Re: Nature of Light and Special Relativity

ALBERT EINSTEIN, Typed Letter Signed, to George Aristotle Solounias, September 18, 1952, Princeton, New Jersey. On Einstein's embossed stationery; with envelope. 1 p., 8.5" x 11".

Complete Translation

September 18, 1952

Mr. George Aristotle Solounias

4, Hill Street

Athens 1, GREECE

Dear Sir:

1) Your considerations about the Michelson experiment presuppose that the classical rule of composition of velocities would hold. That rule does, however, not conform with other experimental facts.

2) Your proposition concerning interference experiments is not workable for the reason that light coming from different sources does not interfere.

3) The hypothesis of dependence of light velocity from the motion of the source is not compatible with observations on double-stars. (De Sitter)

Sincerely yours,

A.Einstein.

Albert Einstein.

Historical Background

By the late-nineteenth century, scientists had long believed that just as waves move in the water and sound waves move in the air, light waves also needed a substance in which to move. In the eighteenth century, scientists named this substance "aether" and believed it filled the vacuum of space. In 1887, Albert A. Michelson and Edward Morley developed a device called an interferometer to attempt to prove the existence of aether by measuring the "aether wind" through which the earth moved. They proposed to measure the speed of light traveling in different directions to see what effect the aether wind had on different beams of light. Their results that there were no substantial differences in the speed of light puzzled scientists, who responded with new theories to explain the results of Michelson-Morley experiment.

In 1905, Albert Einstein developed his special theory of relativity, using the Lorentz factor (the factor by which time, length, and mass change for an object moving at speeds close to the speed of light), developed by Hendrik Lorentz (1853-1928). Einstein explained the results of the Michelson-Morley experiment by considering the measurement of the speed of light to be a constant by definition, or a law of nature. Considering the speed of light to be a constant led to revisions in the concepts of space and time.

In special relativity, an object's mass (m), total energy (E), and momentum (p) are related by the speed of light constant (c) according to the equation:

E2 = p2c2 + m2c4

If an object is at rest (p=0), the equation simplifies to the familiar:

E0 = mc2

Albert Einstein fled Nazi Germany in 1932, and in 1933, he emigrated to the United States, where he joined the faculty of the Institute for Advanced Study in Princeton, New Jersey.

On September 7, 1952, George A. Solounias wrote to Einstein from Athens, Greece. He asserted that the "Michelson-Morley experiment proves directly that the speed of light is not constant and it depends on the motion of the emitting source" and provided reasons for his conclusion. Solounias provided an example of two men on a ship traveling the same distance, one vertically, the other horizontally in the direction the ship is sailing. Observers on shore and on the deck see that the men cover different distances. Solounias asserted that the Michelson-Morley experiment is the same with the substitution of the men by beams of light and the ship by the Earth. "But Science," Solounias continued, "in explaning theoretically Michelson-Morley experiment, assumes that, if earth's motion in the direction O B, is added to that of the light beams emitted from O towards the mirrors A and B, the resulting velocities of these beams would be unequal and consequently they would cover the equal distances OA and OB in unequal intervals of time. Therefore, the beams would reach the mirrors A and B not simultaneously and then we should observe fringes of interference."

Solounias rejected this conclusion in part: "But this thought is erroneous for the following reasons. We put the supposition that the earth's motion is added to that of the light and consequently that the resulting velocities will be unequal. That is correct; but it is not correct – after this supposition – the admittance that the two beams of light with the unequal velocities have to cover ‘the equal distances O A and O B.' In fact, they have to cover not the equal distances O A and O B but the unequal distances O A' and O B' – resulting by the combination of the motion of the earth and that of the light – with the correspondingly unequal velocities O A' and O B'; and since the difference of the courses of the beams is covered exactly and correspondingly by the difference of the velocities of these beams, they reach the mirrors simultaneously, and we don't observe fringes of interference during the performance of Michelson-Morley experiment."

Solounias went on to suggest some laboratory experiments that could illustrate the same idea. He concluded, "Please, let me hope that you will be very kind to write to me your opinion on my theoretical explanation of Michelson-Morley experiment. As to the different problems arising by accepting this explanation, I believe that you will confront them effectively."

Einstein responded on September 18 with this letter. In it, Einstein referenced the work of Willem de Sitter on double stars. In 1913, de Sitter described the de Sitter effect and used it to support the special theory of relativity against the competing 1908 emission theory of Walther Ritz that posited a variable speed of light. De Sitter argued that if Ritz's theory were true, a star in a double-star system would emit light at different speeds at different parts of its orbital path, creating "slow" and "fast" light that would present a scrambled image. De Sitter observed no cases of such behavior, leading him to conclude that Ritz's theory was incorrect.

Two months later, Solounias replied to Einstein's criticisms in this letter with additional suggested experiments. In response to Einstein's third point, Solounias wrote, "The fact that the hypothesis of dependence of light velocity from the motion of the source is not compatible with De Sitter's observations on double-stars, is not enough – this is my opinion – to deter, to prevent the performance of a direct experiment for the verification of the constancy or not of the velocity of light. Science is so full of Your theories of Relativity and its evolution is so much depended on them, that more than one direct experiments must be invented and performed for the verification of the dependence or not of light velocity from the motion of the source, especially, after the new-opposite-explanation of Michelson experiment, on which (experiment) You have founded your theory of Special Relativity."

He also reflected on the problem of whether light consisted of particles or waves: "The great difficulty which arises with the admittance of the new explanation of Michelson experiment lies – in my opinion – elsewhere. It is due to the fact that the phenomena of interference and diffraction, can be explained only by the hypothesis that light is transmitted by waves – it is weightless. But when – in the new explanation – we assume that the velocity of photons is added to that of the emitting source we probably admit that light is composed of material particles which obey to the law of composition of velocities. Then, it is obvious that we reject the wave character of light. Consequently, the phenomena of interference and diffraction and polarization too, supporting the wave character of light remain unexplained." He proposed resolving the "problem of the dual nature of light, in acting both as waves and as particles" by concluding that "Photons are material particles in waving motion. That is to say: When we illustrate light waves we merely draw the orbits of photons."

Solounias concluded that "This hypothesis is in accordance with all light phenomena," then boldly declared, "I think that this hypothesis is more convincing and less metaphysical than Your assumption that: ‘space has the physical property of transmitting waves' which You stated when You had been forced to oust the ‘enfant terrible' – ether – from the scientific books, when You had been obliged to assume the transmission of waves without a medium."

In response to a query in May 1953 from E. Noe about the Miller experiments relating to the Michelson and Morley experiment, Einstein employed one of his favorite aphorisms: "God is refined but he is not malicious." Einstein made the remark when he first visited Princeton University in 1921 and was told that a new experiment had upset his theory of relativity. He believed that the universe was orderly with predictable laws and generally rejected the unpredictability of quantum theory.



Albert Einstein (1879-1955) was born in the Kingdom of Wurttemberg in the German Empire to non-observant Ashkenazi Jewish parents. In 1894, the Einstein family moved to Italy. Einstein went to Switzerland to finish his secondary schooling, and graduated from the Swiss Federal Polytechnic in Zürich in 1900. In 1903, he married Mileva Maric (1875-1948), with whom he had two sons. In 1919, they divorced and he married his cousin Elsa Löwenthal. In 1905, he received a Ph.D. from the University of Zürich. From 1908 to 1932, he taught at a series of universities in Switzerland, the Austrian Empire, and the German Empire. As a theoretical physicist, he published ground-breaking papers as early as 1905 and developed the theory of relativity including the mass–energy equivalence formula, E = mc2. In 1922, he received the Nobel Prize in Physics for the discovery of the photoelectric effect. In January 1933, when Adolph Hitler came to power, Einstein was visiting the United States and remained here, becoming a citizen in 1940. A year earlier, he signed a letter to President Franklin D. Roosevelt warning that Germany could develop a nuclear bomb, and urging the U.S. to become involved in uranium research, thus beginning the "Manhattan project." Though he focused on the need to defeat Hitler during the war, afterwards he became known for efforts to further world peace. At the Institute for Advanced Study in Princeton, N.J., from 1933 until his death in 1955, he worked unsuccessfully to develop a unified field theory and to refute the accepted interpretation of quantum physics. Considered the father of modern physics and one of the most prolific intellects of history, Einstein published more than 300 scientific papers and over 150 non-scientific works.

George Aristotle Solounias (1901-1981) was born in Pythagoreio of Samos, Greece, and received a high school education. He worked as a writer and as a businessman for land developer and importer Gerassimos Panas in Athens; he retired in the mid-1960s. Solounias was largely self-educated and was an amateur astronomer. He submitted several papers to the Academy of Athens about gravity and the solar system, and he published Paul, or the Search of the Absolute Truth (A Philosophical Dialogue) (1938, Greek), The Error of Newton (1939, Greek), Is There Universal Gravity? (1941, Greek), and The Origin of the Solar System: A New Theory (English, 1973). In addition to Einstein, Solounias also corresponded with J. Robert Oppenheimer between 1949 and 1964. Solounias married elementary school teacher Ioanna Katsimatidou (1908-1964) in 1933, and they had three children: Sibyl, who was a housewife and worked in a bank; Aristotle, who became a well-known artist; and Nikos, who is a professor of anatomy and evolutionary biology at the New York Institute of Technology and a research associate at the American Museum of Natural History.

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