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Keyword: generalrelativity

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  • Astronomy Picture of the Day -- Two Black Holes Dancing in 3C 75

    09/27/2014 9:50:48 PM PDT · by SunkenCiv · 22 replies
    NASA ^ | September 28, 2014 | (see photo credit)
    Explanation: What's happening at the center of active galaxy 3C 75? The two bright sources at the center of this composite x-ray (blue)/ radio (pink) image are co-orbiting supermassive black holes powering the giant radio source 3C 75. Surrounded by multimillion degree x-ray emitting gas, and blasting out jets of relativistic particles the supermassive black holes are separated by 25,000 light-years. At the cores of two merging galaxies in the Abell 400 galaxy cluster they are some 300 million light-years away. Astronomers conclude that these two supermassive black holes are bound together by gravity in a binary system in part...
  • Stephen Hawking stuns physicists by declaring ‘there are no black holes’—says there are GREY ones

    01/25/2014 12:03:14 AM PST · by Olog-hai · 35 replies
    Daily Mail (UK) ^ | 15:59 EST, 24 January 2014 | Mark Prigg
    Stephen Hawking has shocked physicists by admitting “there are no black holes”. In a paper published online, Professor Hawking instead argues there are “grey holes”. “The absence of event horizons means that there are no black holes—in the sense of regimes from which light can't escape to infinity,” he says in the paper, called Information Preservation and Weather Forecasting For Black Holes.He says that the idea of an event horizon, from which light cannot escape, is flawed. He suggests that instead light rays attempting to rush away from the black hole’s core will be held as though stuck on a...
  • Meet the Indian who took on Stephen Hawking

    08/02/2004 10:16:56 PM PDT · by CarrotAndStick · 97 replies · 5,002+ views
    Rediff.com ^ | August 03, 2004 10:06 IST | Rediff.com
    An Indian theoretical physicist who questioned the existence of black holes and thereby challenged Stephen Hawking of Britain at last feels vindicated. But he is sad. Abhas Mitra, at the Bhabha Atomic Research Centre (BARC) in Mumbai, was perhaps the first and the only scientist who had the guts to openly challenge Hawking of Cambridge University who is regarded by many as the modern-day Einstein. For over 30 years Hawking and his followers were perpetuating the theory that black holes -- resulting from gravitational collapse of massive stars -- destroy everything that falls into them preventing even light or information...
  • A surge of attacks against classical GR (General Relativity)

    10/01/2014 1:02:17 PM PDT · by EveningStar · 9 replies
    The Reference Frame ^ | September 29, 2014 | Luboš Motl
    ... Well, even 90 years isn't enough, it seems, so right now, we are entering new waters – the denial of some basic results of general relativity, our modern theory of gravity that has been around and available to everyone since 1916. So in the last week, hundreds of publications informed their readers that it's been "mathematically proven" that the big bang theory is wrong and the black holes don't exist. These nutty claims boil down to some papers by a crackpot named Ms Laura Mersini-Houghton (no, I really, really won't accept her doctorate) who had previously claimed that she...
  • The First Test That Proves General Theory of Relativity Wrong

    02/20/2014 3:47:32 PM PST · by Kevmo · 290 replies
    Softpedia.com ^ | March 24th, 2006, 12:39 GMT · | By Vlad Tarko
    http://news.softpedia.com/news/The-First-Test-That-Proves-General-Theory-of-Relativity-Wrong-20259.shtml According to Einstein's theory of general relativity, a moving mass should create another field, called gravitomagnetic field, besides its static gravitational field. This field has now been measured for the first time and to the scientists' astonishment, it proved to be no less than one hundred million trillion times larger than Einstein's General Relativity predicts. According to Einstein's theory of general relativity, a moving mass should create another field, called gravitomagnetic field, besides its static gravitational field. This field has now been measured for the first time and to the scientists' astonishment, it proved to be no less than...
  • Astronomy Picture of the Day -- Spin up of a Supermassive Black Hole

    03/12/2013 7:07:02 PM PDT · by SunkenCiv · 24 replies
    NASA ^ | March 12, 2013 | (see photo credit)
    Explanation: How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein's General Theory of Relativity, which predicts several amazing and unusual things. Perhaps its most easily testable prediction, though, is that matter entering a maximally rotating black hole should be last seen orbiting at near the speed of light, as seen from far away. This prediction...
  • New data support Einstein on accelerating universe

    04/03/2012 1:00:38 AM PDT · by U-238 · 59 replies
    Science News ^ | 2/2/2012 | Elizabeth Quill
    Einstein is still the boss, say researchers with the BOSS project for measuring key properties of the universe. BOSS, for Baryon Oscillation Spectroscopic Survey, has measured the distance to faraway galaxies more precisely than ever before, mapping the universe as it existed roughly 6 billion years ago, when it was only 63 percent of its current size. The findings suggest that the mysterious “dark energy” causing the universe to expand at an accelerating rate was foreseen by Einstein, the researchers reported April 1 at the American Physical Society meeting. To keep the universe in a static state, Einstein added a...
  • Einstein's Gravity Protects Earth [Celestial Mechanics Porn]

    07/05/2009 5:28:04 AM PDT · by Lonesome in Massachussets · 26 replies · 989+ views
    Sky and Telescope Website ^ | July 1, 2009 | Johannes Hirn
    If the universe obeyed Newton's laws of gravity, there would be about a 60% chance that Mercury would head toward the Sun or Venus during the Sun’s lifetime. But according to a new study, corrections to Newton's laws using Einstein's theory of gravity (general relativity) lower these chances to about 1%. That’s good news, because if Mercury had a near miss with Venus or the Sun, it could wreak havoc on Earth.
  • Three cosmic enigmas, one audacious answer [bye-bye to black holes?]

    03/09/2006 8:34:42 PM PST · by snarks_when_bored · 103 replies · 2,349+ views
    New Scientist ^ | March 9, 2006 | Zeeya Merali
    Three cosmic enigmas, one audacious answer 09 March 2006 Exclusive from New Scientist Print Edition Zeeya Merali DARK energy and dark matter, two of the greatest mysteries confronting physicists, may be two sides of the same coin. A new and as yet undiscovered kind of star could explain both phenomena and, in turn, remove black holes from the lexicon of cosmology. The audacious idea comes from George Chapline, a physicist at Lawrence Livermore National Laboratory in California, and Nobel laureate Robert Laughlin of Stanford University and their colleagues. Last week at the 22nd Pacific Coast Gravity Meeting in Santa Barbara,...
  • Honoring Einstein and one man who proved him right

    07/17/2005 10:35:09 AM PDT · by Lonesome in Massachussets · 14 replies · 486+ views
    June 30, 2005 ^ | Rocco B. Colella
    A Lexington man's contribution to Albert Einstein's theory of relativity was celebrated last week at the Westford observatory where the theory was put to the test 40 years ago. About 100 invited guests at the Massachusetts Institute of Technology's Haystack Observatory in Westford listened as Dr. Irwin Shapiro discussed the fourth test of Einstein's general theory of relativity. Einstein published three of his famous articles in 1905, including the theory of relativity. The World Year of Physics is commemorating the centennial anniversary of Einstein's most accomplished year, along with remembering Shapiro's experiment.
  • Gödel and Einstein: Friendship and Relativity

    12/21/2004 7:47:50 PM PST · by snarks_when_bored · 37 replies · 1,030+ views
    The Chronicle Review ^ | December 17, 2004 | Palle Yourgrau
    Gödel and Einstein: Friendship and RelativityBy PALLE YOURGRAU In the summer of 1942, while German U-boats roamed in wolf packs off the coast of Maine, residents in the small coastal town of Blue Hill were alarmed by the sight of a solitary figure, hands clasped behind his back, hunched over like a comma with his eyes fixed on the ground, making his way along the shore in a seemingly endless midnight stroll. Those who encountered the man were struck by his deep scowl and thick German accent. Speculation mounted that he was a German spy giving secret signals to enemy...
  • After 45 Years (and $700 Million), a Gravity Experiment Takes Flight

    04/13/2004 10:00:41 PM PDT · by neverdem · 9 replies · 557+ views
    NY Times ^ | April 13, 2004 | DENNIS OVERBYE
    Even its critics admit that it was a great idea in 1959. It was then that three Stanford scientists, dangling their legs in a university swimming pool, agreed to team up on an ambitious effort to peer deep into the heart of the strangeness that is Albert Einstein's legacy. Now 45 years and $700 million later, their dream has materialized as a van-size assemblage of plumbing, electronics and quartz, known unpoetically as Gravity Probe B, sitting atop a rocket at Vandenberg Air Force Base in California. It is to be launched into orbit next Monday on an 18-month mission. When...
  • Time Trip - questions and answers (How widely accepted is the theory that we can travel in time?)

    12/25/2003 8:12:15 PM PST · by Momaw Nadon · 91 replies · 2,512+ views
    BBC ^ | Friday, December 26, 2003 | BBC
    The Future According to Professor Paul Davies "Scientists have no doubt whatever that it is possible to build a time machine to visit the future". Since the publication of Einstein’s Special Theory of Relativity in 1905, few, if any, scientists would dispute that time travel to the future is perfectly possible. According to this theory, time runs slower for a moving person than for someone who is stationary. This has been proven by experiments using very accurate atomic clocks. In theory, a traveller on a super high-speed rocket ship could fly far out into the Universe and then come back...
  • Cassini Proves Einstein Right — So Far

    10/03/2003 5:21:23 AM PDT · by Lonesome in Massachussets · 46 replies · 367+ views
    Sky and Telescope Website ^ | October 2, 2003 | Govert Schilling
    [The Cassini spacecraft will reach Saturn in July 2004 and should send the small Huygens probe into the hazy atmosphere of Titan in January 2005. On its way there, Cassini flew nearly behind the Sun from Earth's point of view two years ago, offering a chance for a highly precise test of general relativity. Courtesy NASA/JPL.] Albert Einstein still rules. His 1915 theory of gravity, the general theory of relativity, has just passed its most stringent test by far. Extremely precise measurements of the radio link between Earth and NASA’s Cassini spacecraft, bound for Saturn, match general relativity's predictions extraordinarily...