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Question on black holes

  1. Aug 2, 2009 #1
    I apologize i do not know if this question makes practical sense i am only a person interested in physics, Is it possible to calculate a rough estimate of all of the matter being absorbed by all known black holes in existence , and than to even more generally estimate the amount of UNKNOWN black holes in the universe (probably impossible) and the matter they may be consuming To see if it has a chance of having any affect at all on the calculations that were done to estimate how much matter was in the universe and if there would be a big crunch or an ever expanding universe.
  2. jcsd
  3. Aug 3, 2009 #2


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    The calculation certainly is possible, and I will sketch it out rather than give an actual calculation:

    Knowing the rough percentage of stars which form are in the mass limit that will form a black hole, one can calculate the average black hole formation. Since black holes that form alone will likely never accrete appreciable amounts of matter, only that fraction of those in binary systems will. Certainly, judging by what we see happening in neutron star binaries (and some black hole binaries) the rate of accretion could be estimated. This would give a rough amount of how much matter has been consumed by black holes.

    However, this is wholly irrelevant to your question because the mass that is consumed by black holes stays in our universe and still contributes to the fate of the universe problem by virtue of its gravity just like everything else.
  4. Aug 4, 2009 #3
    I agree with Nabeshin. When calculating how much matter there is in the universe, we are already including the matter contained in black holes. For example, when figuring out how much matter we have in our galaxy, we look at stars to see how fast they are orbiting the center of the galaxy. This speed depends on the gravity of matter that is both seen (e.g. stars) and unseen (e.g. black holes and dark matter). So, from the speeds of stars at a variety of distances from the center of the galaxy, we can deduce how much matter--seen and unseen--the galaxy has. Similarly, when figuring out the average matter density of the universe, the effect of black holes is included.
  5. Aug 19, 2009 #4
    Ahh see that is what interests me in physics so much, a month later after asking the question i finally realize that the question I asked wasnt the question i had at all. The REAL question i had was weather or not matter consumed by a black hole of ANY type leaves our universe in any REAL sense, and weather the laws of the conservation of matter as i understand them to be vanish when it comes to a black hole. Without this question my question could not be answered, and with this question my question seems rather ignorant to the laws of physics

    Anyways thank you both for your answers, i do understand now (to the best of my ability)
    I shall continue to learn :)
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