luminiferous ether

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pages: 208 words: 70,860

Paradox: The Nine Greatest Enigmas in Physics by Jim Al-Khalili

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Albert Einstein, Albert Michelson, anthropic principle, Arthur Eddington, butterfly effect, clockwork universe, complexity theory, dark matter, Edmond Halley, Edward Lorenz: Chaos theory, Ernest Rutherford, Henri Poincaré, invention of the telescope, Isaac Newton, luminiferous ether, Magellanic Cloud, Olbers’ paradox, Schrödinger's Cat, Search for Extraterrestrial Intelligence, The Present Situation in Quantum Mechanics, Wilhelm Olbers

So, in the direction of travel of the car, the sound waves are moving away from it more slowly than they are moving away at right angles to it. This is because the speed at which the sound waves move ahead of the car is the difference between the speed of the waves in air and the speed of the car. Michelson and Morley applied this principle to light waves. They devised an ingenious experiment—one which they were convinced would be the first to confirm and detect the existence of the luminiferous ether. They began by assuming that the Earth is moving through the ether as it orbits the Sun, which it does at about 100,000 kilometers per hour. In their laboratory experiment they measured, with incredible accuracy, the time it took two light beams to travel along two different paths of equal distance, one in the direction of the Earth’s motion as it orbited the Sun and the other at right angles to it.

This means that there are no experiments we could perform that would tell us whether we were truly standing still or moving. The second postulate was the revolutionary one, although it sounds quite innocent at first. Einstein stated that light does indeed have the wavelike property that its speed is independent of the speed of its source (just like the sound waves from a moving car). Yet at the same time, and unlike sound waves, light does not require a medium to pass through; the luminiferous ether does not exist and light waves can move across truly empty space. So far, so good; no paradox here—and nothing, you might think, in either of these innocuous postulates that you might have difficulty subscribing to. They certainly don’t sound like statements that lead to a revolutionary view of space and time. But they do. Each postulate is, on its own, innocent. It is when the two are combined that we see how profound Einstein’s ideas were.


pages: 492 words: 149,259

Big Bang by Simon Singh

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Albert Einstein, Albert Michelson, All science is either physics or stamp collecting, Andrew Wiles, anthropic principle, Arthur Eddington, Astronomia nova, Brownian motion, carbon-based life, Cepheid variable, Chance favours the prepared mind, Commentariolus, Copley Medal, cosmic abundance, cosmic microwave background, cosmological constant, cosmological principle, dark matter, Dava Sobel, Defenestration of Prague, discovery of penicillin, Dmitri Mendeleev, Edmond Halley, Edward Charles Pickering, Eratosthenes, Ernest Rutherford, Erwin Freundlich, Fellow of the Royal Society, fudge factor, Hans Lippershey, Harlow Shapley and Heber Curtis, Harvard Computers: women astronomers, Henri Poincaré, horn antenna, if you see hoof prints, think horses—not zebras, Index librorum prohibitorum, invention of the telescope, Isaac Newton, John von Neumann, Karl Jansky, Louis Daguerre, Louis Pasteur, luminiferous ether, Magellanic Cloud, Murray Gell-Mann, music of the spheres, Olbers’ paradox, On the Revolutions of the Heavenly Spheres, Paul Erdős, retrograde motion, Richard Feynman, Richard Feynman, scientific mainstream, Simon Singh, Solar eclipse in 1919, Stephen Hawking, the scientific method, Thomas Kuhn: the structure of scientific revolutions, unbiased observer, V2 rocket, Wilhelm Olbers, William of Occam

Confronted with this apparent paradox, scientists began to wonder if a vacuum was really empty. The jar had been evacuated of air, but perhaps there was something remaining inside, something that provided the medium for conveying light. By the nineteenth century, physicists had proposed that the entire universe was permeated by a substance they termed the luminiferous ether, which somehow acted as a medium for carrying light. This hypothetical substance had to possess some remarkable properties, as pointed out by the great Victorian scientist Lord Kelvin: Now what is the luminiferous ether? It is matter prodigiously less dense than air – millions and millions and millions of times less dense than air. We can form some sort of idea of its limitations. We believe it is a real thing, with great rigidity in comparison with its density: it may be made to vibrate 400 million million times per second; and yet be of such density as not to produce the slightest resistance to any body going through it.

He once nostalgically referred to the ‘beloved old ether, which is now abandoned, though I personally still cling a little to it’. The crisis of the non-existent ether was magnified because it was supposed to have been responsible for carrying both the electric and magnetic fields as well as light. The dire situation was nicely summarised by the science writer Banesh Hoffmann: First we had the luminiferous ether, Then we had the electromagnetic ether, And now we haven’t e(i)ther. So, by the end of the nineteenth century Michelson had proved that the ether did not exist. Ironically, he had built his career on a whole series of successful experiments relating to optics, but his greatest triumph was the result of a failed experiment. His goal all along had been to prove the existence of the ether, not its absence.


pages: 257 words: 80,100

Time Travel: A History by James Gleick

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Ada Lovelace, Albert Einstein, Albert Michelson, Arthur Eddington, augmented reality, butterfly effect, crowdsourcing, Doomsday Book, index card, Isaac Newton, John von Neumann, luminiferous ether, Marshall McLuhan, Norbert Wiener, pattern recognition, Richard Feynman, Richard Feynman, Schrödinger's Cat, self-driving car, Stephen Hawking, telepresence, wikimedia commons

Was the ether necessary? Or was it possible to think purely of an electrodynamics of moving bodies, through empty space? We know now that the speed of light in empty space is constant, 299,792,458 meters per second. No rocket ship can overtake a flash of light or reduce that number in the slightest. Einstein struggled (“psychic tension”; “all sorts of nervous conflicts”) to make sense of that: to discard the luminiferous ether, to accept the speed of light as absolute. Something else had to give. On a fine bright day in Bern (as he told the story later), he talked it over with his friend Michele Besso. “Next day I came back to him again and said to him, without even saying hello, ‘Thank you. I’ve completely solved the problem.’ An analysis of the concept of time was my solution.” If light speed is absolute, then time itself cannot be.


pages: 654 words: 204,260

A Short History of Nearly Everything by Bill Bryson

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Albert Einstein, Albert Michelson, Alfred Russel Wallace, All science is either physics or stamp collecting, Arthur Eddington, Barry Marshall: ulcers, Brownian motion, California gold rush, Cepheid variable, clean water, Copley Medal, cosmological constant, dark matter, Dava Sobel, David Attenborough, double helix, Drosophila, Edmond Halley, Ernest Rutherford, Fellow of the Royal Society, Harvard Computers: women astronomers, Isaac Newton, James Watt: steam engine, John Harrison: Longitude, Kevin Kelly, Kuiper Belt, Louis Pasteur, luminiferous ether, Magellanic Cloud, Menlo Park, Murray Gell-Mann, out of africa, Richard Feynman, Richard Feynman, Stephen Hawking, supervolcano, Thomas Malthus, Wilhelm Olbers

There, in the 1880s, a physicist of early middle years named Albert Michelson, assisted by his friend the chemist Edward Morley, embarked on a series of experiments that produced curious and disturbing results that would have great ramifications for much of what followed. What Michelson and Morley did, without actually intending to, was undermine a longstanding belief in something called the luminiferous ether, a stable, invisible, weightless, frictionless, and unfortunately wholly imaginary medium that was thought to permeate the universe. Conceived by Descartes, embraced by Newton, and venerated by nearly everyone ever since, the ether held a position of absolute centrality in nineteenth-century physics as a way of explaining how light traveled across the emptiness of space. It was especially needed in the 1800s because light and electromagnetism were now seen as waves, which is to say types of vibrations.

At a stroke, in a simple formula, Einstein endowed geologists and astronomers with the luxury of billions of years. Above all, the special theory showed that the speed of light was constant and supreme. Nothing could overtake it. It brought light (no pun intended, exactly) to the very heart of our understanding of the nature of the universe. Not incidentally, it also solved the problem of the luminiferous ether by making it clear that it didn't exist. Einstein gave us a universe that didn't need it. Physicists as a rule are not overattentive to the pronouncements of Swiss patent office clerks, and so, despite the abundance of useful tidings, Einstein's papers attracted little notice. Having just solved several of the deepest mysteries of the universe, Einstein applied for a job as a university lecturer and was rejected, and then as a high school teacher and was rejected there as well.


pages: 442 words: 110,704

The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars by Dava Sobel

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Albert Einstein, card file, Cepheid variable, crowdsourcing, dark matter, Dava Sobel, Edmond Halley, Edward Charles Pickering, Ernest Rutherford, Harlow Shapley and Heber Curtis, Harvard Computers: women astronomers, index card, invention of the telescope, Isaac Newton, John Harrison: Longitude, luminiferous ether, Magellanic Cloud, pattern recognition, QWERTY keyboard, Ralph Waldo Emerson, Solar eclipse in 1919, V2 rocket

Immersed now in her astronomy self-education, she found the lens for the new telescope preoccupied her as no figurine or chandelier ever had. “I bought [Charles] Young’s Elements of Astronomy,” she told Pickering, “after reading in a newspaper that it was adapted to the humblest capacity—Well there is in ‘every lowest depth a lower deep’ and I fear to fall into it. “Young calls the vast spaces between the stars a vacuum,” Miss Bruce continued, while another book she read by philosopher John Fiske “speaks of it as the luminiferous ether. I shall hold on to Young.” Pickering obligingly provided her with all the Harvard Observatory’s publications, from volumes of the Annals to offprints of his research reports. “Your paper on Variable Stars of Long Periods,” she said in a thank-you note, “I at once read and with admiration— not of the Tables but of the simple goodness of heart shown in the detailed directions to unskilled amateurs how to become useful aids to Science.”


pages: 478 words: 131,657

Tesla: Man Out of Time by Margaret Cheney

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AltaVista, dematerialisation, fudge factor, invention of radio, luminiferous ether, Menlo Park

Anyone who expects a source of power from transformation of these atoms is talking moonshine.”3 Perhaps it rankled Tesla to hear one of the “new physics” quips being attributed to Professor Sir William Bragg, co-winner of the 1915 Nobel Prize that for a time he had thought to be his. God runs electromagnetics on Monday, Wednesday, and Friday by the wave theory, said Bragg; and the devil runs it by quantum theory on Tuesday, Thursday, and Saturday. Tesla’s thoughts in later life were tending more and more toward a unifying physical theory. He believed that all matter came from a primary substance, the luminiferous ether, which filled all space, and he stoutly maintained that cosmic rays and radio waves sometimes moved more swiftly than light. The younger scientists, most of whom were affiliated with universities, were just beginning to perceive what a garden of earthly delights government-sponsored research could be. Oddly enough it was to be Edison, creator of the modern industrial research laboratory, who threw a spanner into their dreams.


pages: 478 words: 142,608

The God Delusion by Richard Dawkins

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Albert Einstein, anthropic principle, Any sufficiently advanced technology is indistinguishable from magic, Ayatollah Khomeini, Brownian motion, cosmological principle, David Attenborough, Desert Island Discs, double helix, en.wikipedia.org, experimental subject, Fellow of the Royal Society, gravity well, invisible hand, John von Neumann, luminiferous ether, Menlo Park, meta analysis, meta-analysis, Murray Gell-Mann, Necker cube, Peter Singer: altruism, phenotype, placebo effect, planetary scale, Ralph Waldo Emerson, Richard Feynman, Richard Feynman, Schrödinger's Cat, Search for Extraterrestrial Intelligence, stem cell, Stephen Hawking, Steven Pinker, the scientific method, theory of mind, Thorstein Veblen, trickle-down economics, unbiased observer

Steve Grand, in Creation: Life and How to Make It, is almost scathing about our preoccupation with matter itself. We have this tendency to think that only solid, material ‘things’ are ‘really’ things at all. ‘Waves’ of electromagnetic fluctuation in a vacuum seem ‘unreal’. Victorians thought that waves had to be waves ‘in’ some material medium. No such medium was known, so they invented one and named it the luminiferous ether. But we find ‘real’ matter comfortable to our understanding only because our ancestors evolved to survive in Middle World, where matter is a useful construct. On the other hand, even we Middle Worlders can see that a whirlpool is a ‘thing’ with something like the reality of a rock, even though the matter in the whirlpool is constantly changing. In a desert plain in Tanzania, in the shadow of Ol Donyo Lengai, sacred volcano of the Masai, there is a large dune made of ash from an eruption in 1969.


pages: 782 words: 245,875

The Power Makers by Maury Klein

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Albert Einstein, Albert Michelson, Augustin-Louis Cauchy, British Empire, business climate, invention of radio, invention of the telegraph, Isaac Newton, James Watt: steam engine, Louis Pasteur, luminiferous ether, margin call, Menlo Park, price stability, railway mania, the scientific method, trade route, transcontinental railway, working poor

His second line of inquiry was experimental and resulted in nine points that summarized his own theory of electrodynamics.32 In January 1821 Ampère first introduced his notion of molecular currents, which led him to formulate a new theory of matter in which such currents were an integral part not merely of magnetism but of all molecular processes. In devising this theory he resorted to the luminiferous (“light-carrying”) ether as the agent bringing matter and electricity together. Few things baffled or divided scientists more than this mysterious substance. As described by Augustin-Jean Fresnel, a French physicist who argued that light consisted of waves, the luminiferous ether was a gaslike substance through which both light and solids somehow moved. A French mathematician, Augustin-Louis Cauchy, worked out a mathematical basis for the properties of ether that made Fresnel’s theory at least plausible if not satisfying to scientists.33 The wave theory of light required that ether be perfectly elastic and offer no resistance to a body passing through it. To these demands Ampère added a new chemical wrinkle: The ether was not simple but compound in nature and could “only be considered, in the generally adopted theory of two electric fluids, as the combination of these two fluids in that proportion in which they mutually saturate one another.”