Karl Jansky

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pages: 492 words: 149,259

Big Bang by Simon Singh

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, Johannes Kepler, John von Neumann, Karl Jansky, Kickstarter, 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, scientific mainstream, Simon Singh, Solar eclipse in 1919, Stephen Hawking, the scientific method, Thomas Kuhn: the structure of scientific revolutions, unbiased observer, Wilhelm Olbers, William of Occam

The universe in fact is a botched job, but I suppose we shall have to make the best of it.’ Radio astronomy was opening up a new window onto the universe, discovering entirely new objects and providing critical evidence in the Big Bang versus Steady State debate. Regrettably, Karl Jansky, the father of radio astronomy, received virtually no credit during his lifetime for inadvertently inventing the radio telescope and for making the first radio observations of the sky. He passed away in 1950 at the age of just forty-four. It was only in the decade after his death that radio astronomy would establish itself as a truly major discipline within astronomy. However, Karl Jansky was eventually immortalised. In 1973 the International Astronomical Union recognised his contribution by naming the unit of radio flux in his honour. This unit, the jansky, is used by radio astronomers to indicate the strength of any radio source.

The radio link could carry one call at a time at a rate of $75 for the first three minutes—equivalent to almost $1,000 at today’s prices. AT&T was anxious to keep a grip on this lucrative market by offering a high-quality service, so it asked Bell Laboratories to undertake a survey of the natural sources of radio waves, which were interfering with long-distance radio communication by causing a background crackling noise. The task of surveying these annoying radio sources fell to Karl Jansky, a twenty-two-year-old junior researcher who had only just graduated in physics from the University of Wisconsin, where his father had been a lecturer in electrical engineering. Radio waves, like waves of visible light, are part of the electromagnetic spectrum. However, radio waves are invisible and have wavelengths that are much longer than those of visible light. Whereas the wavelengths of visible light are less than a thousandth of a millimetre, radio wavelengths vary from a few millimetres (microwaves) to a few metres (FM radio waves) and a few hundred metres (AM radio waves).

Jansky, however, was determined to get to the bottom of the mystery and spent several more months analysing the baffling interference. Gradually, it emerged that the hiss came from a particular region of the sky and that it peaked every 24 hours. Actually, when Jansky looked at his data more carefully, he found that the peak came every 23 hours and 56 minutes. Almost a full day between peaks, but not quite. Figure 92 Karl Jansky makes adjustments to the antenna that was designed to detect natural sources of radio waves. The Ford Model T wheels are part of the turntable that allowed the antenna to rotate. Jansky mentioned the curious time interval to his colleague Melvin Skellet, who had a Ph.D. in astronomy and who was able to point out the significance of the missing four minutes. Each year the Earth spins on its axis 3651/4 times, and each day lasts 24 hours, so one year consists of 3651/4 × 24 = 8,766 hours.

pages: 476 words: 118,381

Space Chronicles: Facing the Ultimate Frontier by Neil Degrasse Tyson, Avis Lang

Albert Einstein, Arthur Eddington, asset allocation, Berlin Wall, carbon-based life, centralized clearinghouse, cosmic abundance, cosmic microwave background, dark matter, Gordon Gekko, informal economy, invention of movable type, invention of the telescope, Isaac Newton, Johannes Kepler, Karl Jansky, Kuiper Belt, Louis Blériot, low earth orbit, Mars Rover, mutually assured destruction, orbital mechanics / astrodynamics, Pluto: dwarf planet, RAND corporation, Ronald Reagan, Search for Extraterrestrial Intelligence, SETI@home, space pen, stem cell, Stephen Hawking, Steve Jobs, the scientific method, trade route

Yes, he is somewhat stronger than your average astrophysicist, but astrophysicists can now “see” into every major part of the electromagnetic spectrum. Lacking this extended vision, we would be not only blind but ignorant, because many astrophysical phenomena reveal themselves only in certain “windows” within the spectrum. Let’s peek at a few discoveries made through each window to the universe, starting with radio waves, which require very different detectors from those found in the human retina. In 1931 Karl Jansky, then employed by Bell Telephone Laboratories and armed with a radio antenna he himself built, became the first human to “see” radio signals emanating from somewhere other than Earth. He had, in fact, discovered the center of the Milky Way galaxy. Its radio signal was so intense that if the human eye were sensitive only to radio waves, then the galactic center would be one of the brightest sources in the sky.

When radio emissions from Saturn were discovered, for instance, it was simple enough for astronomers to hook up a radio receiver equipped with a speaker; the signal was then converted to audible sound waves, whereupon more than one journalist reported that “sounds” were coming from Saturn, and that life on Saturn was trying to tell us something. With much more sensitive and sophisticated radio detectors than were available to Karl Jansky, astrophysicists now explore not just the Milky Way but the entire universe. As a testament to the human bias toward seeing-is-believing, early detections of radio sources in the universe were often considered untrustworthy until they were confirmed by observations with a conventional telescope. Fortunately, most classes of radio-emitting objects also emit some level of visible light, so blind faith was not always required.

Wonders of the Universe by Brian Cox, Andrew Cohen

a long time ago in a galaxy far, far away, Albert Einstein, Albert Michelson, Arthur Eddington, California gold rush, Cepheid variable, cosmic microwave background, dark matter, Dmitri Mendeleev, Isaac Newton, James Watt: steam engine, Johannes Kepler, Karl Jansky, Magellanic Cloud, Mars Rover, Solar eclipse in 1919, Stephen Hawking, the scientific method, trade route

The Very Large Array (VLA) is a radio astronomy observatory consisting of 27 identical dishes, each 25 metres (82 feet) in diameter, arranged in a gigantic Y shape across the landscape. Although each dish works independently, they can be combined together to create a single antenna with an effective diameter of over 36 kilometres (22 miles). This allows this vast virtual telescope to achieve very high-resolution images of the sky at radio wavelengths. Radio astronomy has a history dating back to the 1930s, when the astronomer Karl Jansky discovered that the Universe could be explored not just through the visible part of the electromagnetic spectrum, but also through the detection of radio waves. Over a period of several months, Jansky used an antenna that looked more like a Meccano set than the VLA to record the radio waves from the sky. He initially identified two types of signal: radio waves generated by nearby thunderstorms, and radio waves generated by distant thunderstorms.

pages: 253 words: 80,074

The Man Who Invented the Computer by Jane Smiley

1919 Motor Transport Corps convoy, Alan Turing: On Computable Numbers, with an Application to the Entscheidungsproblem, Albert Einstein, anti-communist, Arthur Eddington, British Empire, c2.com, computer age, Fellow of the Royal Society, Henri Poincaré, IBM and the Holocaust, Isaac Newton, John von Neumann, Karl Jansky, Norbert Wiener, Norman Macrae, Pierre-Simon Laplace, RAND corporation, Turing machine, Vannevar Bush, Von Neumann architecture

In 1930, at the same time Atanasoff was working on his dissertation at the University of Wisconsin, Stibitz was working on his at Cornell University. Stibitz’s dissertation, like Atanasoff’s, involved extensive and tedious calculations. But Stibitz went to work for Bell Labs in New York City. Bell Labs, a joint enterprise belonging to Western Electric and AT&T, was in both the discovery business and the invention business. In 1932, Karl Jansky had detected radio noise that originated at the center of the Milky Way; in 1933, Bell Labs scientists had managed to transmit stereophonic sound over telephone wires (a symphony recorded in Philadelphia was transmitted to Washington, D.C.). Stibitz, whose doctorate was in applied mathematics, was surrounded by equipment as well as engineers. Like Atanasoff, Stibitz was known as a tinkerer. It was therefore not surprising to his colleagues that when in November 1937 he built his Complex Number Calculator, he named it the “Model K”; “K” stood for kitchen, because, he said, it was based on electromagnetic relays (not the same as the devices Zuse calls relays)—flashlight bulbs, a dry cell battery, and some metal strips he cut from a tin can—that he found and put together in his kitchen.

pages: 550 words: 154,725

The Idea Factory: Bell Labs and the Great Age of American Innovation by Jon Gertner

Albert Einstein, back-to-the-land, Black Swan, business climate, Claude Shannon: information theory, Clayton Christensen, complexity theory, corporate governance, cuban missile crisis, Edward Thorp, horn antenna, Hush-A-Phone, information retrieval, invention of the telephone, James Watt: steam engine, Karl Jansky, knowledge economy, Leonard Kleinrock, Metcalfe’s law, Nicholas Carr, Norbert Wiener, Picturephone, Richard Feynman, Robert Metcalfe, Sand Hill Road, Silicon Valley, Skype, Steve Jobs, Telecommunications Act of 1996, traveling salesman, undersea cable, uranium enrichment, William Shockley: the traitorous eight

The distinctions could be real enough. A discovery often describes a scientific observation of the natural world—the first observation of Jupiter’s moons, for example, or the isolation of a bacteria that causes a deadly plague. Also, a discovery could represent a huge scientific achievement but an economic dead end. In the early 1930s, for instance, at the Bell Labs radio facility in Holmdel, New Jersey, a young engineer named Karl Jansky created a movable antenna to research atmospheric noise. With this antenna, he observed a steady hiss emanating from the Milky Way. In this moment, Jansky had essentially started the field of radio astronomy—a discovery that paid a lasting dividend to his and Bell Labs’ renown. On the other hand, it never led to any kind of profitable telecommunications invention or device.28 John Bardeen, the most careful of men, referred to his transistor work as a “discovery” of “transistor action”; he and Brattain had effectively observed in their experiment how a current applied to a slightly impure slice of germanium could hasten the movement of microscopic holes inside and thus amplify a signal.

pages: 661 words: 169,298

Coming of Age in the Milky Way by Timothy Ferris

Albert Einstein, Albert Michelson, Alfred Russel Wallace, anthropic principle, Arthur Eddington, Atahualpa, Cepheid variable, Commentariolus, cosmic abundance, cosmic microwave background, cosmological constant, cosmological principle, dark matter, delayed gratification, Edmond Halley, Eratosthenes, Ernest Rutherford, Gary Taubes, Harlow Shapley and Heber Curtis, Harvard Computers: women astronomers, Henri Poincaré, invention of writing, Isaac Newton, Johannes Kepler, John Harrison: Longitude, Karl Jansky, Lao Tzu, Louis Pasteur, Magellanic Cloud, mandelbrot fractal, Menlo Park, Murray Gell-Mann, music of the spheres, planetary scale, retrograde motion, Richard Feynman, Search for Extraterrestrial Intelligence, Searching for Interstellar Communications, Solar eclipse in 1919, source of truth, Stephen Hawking, Thales of Miletus, Thomas Kuhn: the structure of scientific revolutions, Thomas Malthus, Wilhelm Olbers

Noteworthy Events: Kurt Gödel’s second incompleteness theorem indicates that the consistency of any system, including scientific systems, cannot be proved internally—i.e., that mathematics, and science are inherently open-ended. Time: 1932 Noteworthy Events: James Chadwick discovers the neutron. Noteworthy Events: Carl Anderson, without knowing of Dirac’s 1931 paper postulating its existence, discovers the positron. Noteworthy Events: Karl Jansky finds that the Milky Way emits radio waves, opening door on the science of radio astronomy. Time: 1935 Noteworthy Events: Hideki Yukawa predicts existence of the meson. Time: 1939 Noteworthy Events: Niels Bohr and John Archibald Wheeler develop the theory of nuclear fission. Noteworthy Events: Hans Bethe and Carl Friedrich von Weizsäcker independently arrive at theory of the carbon and proton-proton reactions in stars.