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Black Holes

  1. Nov 12, 2005 #1
    It's easy enough for us to change matter into energy, take a wood log and burn it, but is there any way we know to change energy to matter?

    What if black holes were doing it?

    Catching and compacting energy and assembling it into a particle that has no gravity (or maybe has anti-gravity?) so it can float free from the black hole.

    I know this is highly speculative and it would be an unknown particle, one that we would have trouble detecting.
  2. jcsd
  3. Nov 12, 2005 #2
    yes, you could change energy into matter/antimatter pairs, and if they annilate each other the same amount of energy will be released in gamma rays
  4. Nov 12, 2005 #3
    well, it is not that easy to change matter into energy, while burning a log of wood you are not changing matter into energy but rather, what you are doing is releasing the energy traped in various chemical bonds.
    And yes it is possible to create matter from raw energy. But in black holes case is not so, they suck in matter and release energy.
  5. Nov 12, 2005 #4
    Okay, release, not change.

    But don't black holes also collect light? Maybe all particles (EMR and matter) are converted to something else that somehow escape the black hole?

    Like huge garbage disposals.
  6. Nov 12, 2005 #5


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    You are sort of correct. Check around for what you can find on Hawking radiation.
  7. Nov 12, 2005 #6


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    In 1974, Professor Hawking had an idea. He said black holes eventually transmit information about all the matter they swallow into radiation to be spewed out of the black hole. Hawking predicted that a black hole radiates thermally like a hot coal, with a temperature inversely proportional to its mass. For a solar-mass black hole, the temperature is around a millionth of a degree Kelvin - negligible. A black hole of 1012 Kelvins though, is hot enough to emit both massless, and massive particles, such as photons, electrons, and positrons. The thermal energy and hot coal were only analogies, what really happens is that the black hole “evaporates”, and disappears when all of the energy is converted and spewed to, now named in his honor, Hawking radiation. Previously, according to classical general relativity, neither matter nor information could flow from the interior of a black hole to an outside observer, and quantum mechanics though, allows matter and energy to radiate from black holes. Stephen Hawking was in the news in July 2004 for presenting a new theory on the quantum nature of black holes which goes against his own long-held belief about their behavior.

    Because the emission of Hawking radiation is energy, the mass of the hole decreases the longer it lives, unless its being fed. As it shrinks, it gets steadily hotter, it sends out increasing amounts of Hawking radiation, emitting increasingly energetic particles and shrinking faster and faster. When it shrivels up to a mass of about 106 kilograms, the game’s up: within a second, it explodes with about the energy of a million-megaton nuclear bomb. The total time for a black hole to evaporate away is proportional to the cube of its initial mass. For a solar-mass sized-hole, the lifetime is an unobservably long 1064 years. For a 1012 kilogram one, it is about 1010 years - about the estimated present age of the universe.
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