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Light and blackhole

  1. Mar 18, 2008 #1
    this may be very silly question but i want to confirm with you guys...Its been said when light goes into blackhole it cant escape but do we have any proof or observation for light entering a blackhole and disappearing..has anyone observed light entering blackhole and disappearing?
  2. jcsd
  3. Mar 18, 2008 #2
    Until recently, black holes were only a theoretical curiosity with no observational support. Now, the presence of black holes has been inferred in numerous studies from various high-energy phenomena such as quasars, X-ray binary systems and the motion of stars in the inner Galaxy. Nobody has ever directly observed the blackness of a black hole though, but the next generation of optical interferometric telescopes should be able to come close.
  4. Mar 18, 2008 #3


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    Well, one thing about black holes is that if you detect an extremely massive object and you can't see it, that's because it's a black hole. It's not so much the light going in and not coming back out that matters, but the fact that it isn't generating any itself. Before supernova: bright star. After supernova: nothing visible, but presence of a massive object still detectable.
  5. Mar 19, 2008 #4

    Do we have any solid proof or observations that there are heavy massive objects but not visible? how can we know that there is a massive object?
  6. Mar 19, 2008 #5

    George Jones

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    Observations of X-ray binaries provide evidence for black holes formed from stellar collapse. An X-ray binary, so named because it emits X-ray radiation, consists of a dark compact object orbited by a normal star.

    Pairs of stars often orbit each other in binary systems. If massive enough, one star of the pair may collapse, while the other member of the pair remains a normal star. A normal star orbiting closely around a black hole can transfer matter to the black hole. The temperature of the infalling matter increases as it approaches the black hole, until it glows strongly with X-rays that can often be detected easily by telescopes orbiting the Earth.

    So, X-ray binaries supply prime candidates for black holes, but dark compact objects other than black holes might also emit X-rays. However, a compact object more massive than about two solar masses has too much mass to be either a white dwarf or neutron star, and consequently must be a black hole. Observations of the normal star's orbital velocity give estimates for the masses of both objects in an X-ray binary. Compact objects in several observed X-ray binaries have masses that fall in range required for black holes.

    Comparatively new results published in 2003 seem to indicate that in certain systems, matter falls directly into a compact object without hitting a material surface. Since black holes do not have a material surface, this gives strong indirect evidence that the matter is falling into a black hole.

    Observations of the orbital motion of stars and other objects about the central cores of galaxies suggest strongly that supermassive objects reside in galactic cores. The small sizes of galactic cores suggest strongly that the supermassive objects must be black holes. Our own galaxy, the Milky Way, has a three million solar mass black hole in its core.
  7. Mar 19, 2008 #6
    Thank you all for explaining..
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