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Micro black holes, millions / billions of years?

  1. Mar 21, 2015 #1
    Hello,

    Always looking for answers to my questions,
    I had some answers like what micro black holes
    possibly created at the LHC (if it does not evaporate) would put millions or billions of years to be dangerous? I would like to know why

    Sorry if I come to you
    Ps : sorry for the way I did not have too many ideas !!
     
  2. jcsd
  3. Mar 21, 2015 #2

    phinds

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    I do not understand your question.

    Micro black holes are believed to evaporate almost immediately and none are known to have been created at the LHC.

    I have no idea what you are asking about billions of years.

    Please try to restate your question in a more coherent way.
     
  4. Mar 21, 2015 #3
    Hello,

    You're part of a website response I got that
    talking about millions / billions of years ... sorry for that
    question, I had a hard time indeed formulate
    "Moreover, even a black hole mini" stable "might remain for billions of years without absorbing the Earth" and yet another part of response
    "a micro black hole would pass through the Earth and emerges on the other side without causing almost no damage. Because of its very small size. Smaller than an atom." (?)
     
  5. Mar 21, 2015 #4

    phinds

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    Well, if a micro black hole DID last for billions of years inside the Earth, what it did would depend on whether or not it was at the gravitational center. If it was at the gravitational center, then it would just stay there without eating the Earth. If it was off-center and oscillated back and forth through the center then it would hollow out the center. If it were oscillating in a large enough range, it would eat the entire Earth.

    All of that is rather silly, though, since it would NOT last for billions of years.

    Yes, if it approached the Earth from a large distance, it would just pass through the Earth, possibly with very minor accretion of matter right at the line through which it passed through, and then it would just keep going.
     
  6. Mar 21, 2015 #5
    Thank you for your answers, which helps to supplement my knowledge of this magnificent machine, besides, it normally reboot the 23March, at least for
    testing, and May 18 for the famous 6.5 TeV collisions ....
    Small subsidiary question, what would be the arXiv paper that might me
    learn about the LHC and the famous micro black holes?

    Another big thank you to you all and sorry if I ask too much questions ^^
     
  7. Mar 21, 2015 #6

    phinds

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    I don't know what papers might help you. Perhaps someone else will answer. If not, you could start a new thread with that question.
     
  8. Mar 21, 2015 #7

    wabbit

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    There are several papers discussing this, but you should note that they do not talk about ordinary black holes, the production of which would require if my memory is correct an accelerator about 1,000,000,000,000,000 times as powerful as LHC (actually one more zero I think but you get the idea), but about hypothetical black holes that might be produced (and immediately evaporate) if some exotic assumptions such as large additional spacetime dimensions were to hold (none were detected).

    Somewhere to start might instead be:
    http://press.web.cern.ch/backgrounders/safety-lhc.
     
  9. Mar 21, 2015 #8

    Borg

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    I believe that his question is a continuation of the questions in this thread - https://www.physicsforums.com/threads/the-lhc-will-climb-into-energy-some-questions.796413/

    It was explained that high energy collisions exceeding the energy of the LHC have been occurring naturally for billions of years. It was also explained that IF a micro black hole was created, it would evaporate almost immeadiately.

    Edit: fixed the link
     
    Last edited: Mar 21, 2015
  10. Mar 21, 2015 #9
    Borg thank you for your answer but I is not the link
    in question, it brings back to me Page subjects !!

    Can you repost the subject in question? thank you!
     
  11. Mar 22, 2015 #10

    mfb

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    That wouldn't make a large difference. Even if stationary, a stable black hole (something we cannot produce at the LHC) could grow - it would catch the electrons and nuclei close to it, no matter if moving or not.

    @Nitox33: Borg edited the link in case you didn't see it.
     
  12. Mar 22, 2015 #11

    phinds

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    But if it were oscillating in, say, a 100 mile radius back and forth through the center, wouldn't it eventually eat out that whole region, or is it that it would accumulate such a small amount on each pass that even over millions of years it would not eat out the 100 mile radius sphere at the center of the Earth?
     
  13. Mar 22, 2015 #12

    mfb

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    That depends on its size, something at the energy of the LHC would rarely catch an electron or hadron, not making "holes" at all. Either way, the core of earth might be solid, but not solid enough to maintain holes at that pressure. The atoms would quickly rearrange, so the black hole would always be surrounded by matter independent of its motion.
     
  14. Mar 22, 2015 #13

    phinds

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    Good point. So the issue becomes one of how much would it "eat". If it eats enough, then even a modest-radius oscillation would eventually eat the whole Earth, but more likely I would think, it would settle in before then and just sit at the center.
     
  15. Mar 22, 2015 #14

    mfb

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    Again: the motion would not matter. There are atoms at the center in the same way as there are atoms outside. It would continue to absorb matter at some size-dependent rate until the whole earth is a black hole (with a runaway reaction once it reaches the size of a nucleon - sufficient to rip apart every chemical bond in its vicinity and to absorb every incoming nucleus).
     
  16. Mar 22, 2015 #15

    phinds

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    Ah, got it. My idea of it sitting harmlessly at the center is clearly just wrong because the "center" would continue to compress from surrounding matter. I wasn't connecting the dots well. Thanks.
     
  17. Mar 22, 2015 #16
    Oh thank you I did not see, I can not help but think of all that, scared silly and company, thank you again for your answers anyway and I hope not
    being pushy with my questions!

    Have a good week!
     
  18. Mar 22, 2015 #17
  19. Mar 22, 2015 #18

    wabbit

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    By the way I asked not long ago here in pf about when we might hope to produce black holes experimentally (this would be really interesting, and not that scary really, as was said before tiny black holes would evaporate so fast they would never be detected directly, only the products of their instant disintegration would), and the answer was very discouraging : at the very best, being wildly optimistic, we will need to wait several hundred years before we reach that technological capability (and it won't be in accelerators, these are far too puny)
     
  20. Mar 22, 2015 #19

    mfb

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    Well, there are some models where the LHC energy is sufficient. Exotic, but not impossible. We'll know more in a few months. Black holes are easy to search for.
     
  21. Mar 22, 2015 #20

    wabbit

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    Ah yes sorry you're right, I always forget those. Not holding my breath but that sure would be some exciting news.
     
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