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Black holes responsible for missing ET?

  1. May 20, 2008 #1
    Scientists are hoping to create tiny black holes here on earth, which they are pretty sure will evaporate almost immediately due to Hawking radiation. While they consider the risk to be almost nonexistent, I can envision some scientist saying "cool -- wonder if we can make a little bigger one".

    My question is how big would one have to be before it was a danger to the planet, and is it theoretically possible to make such a one in a lab? If so, I can imagine every advanced civilization eventually trying this experiment and ultimately destroying themselves.

    If that is the case it could explain why we have not heard from any advanced civilizations.
  2. jcsd
  3. May 20, 2008 #2
    One thing wrong with your theory: Not even the dumbest idiot would say "Cool, let's make a bigger one."

    We know how to make a bigger one and whether or not we can, once we make a smaller one.

    It's kind of like with atomic bombs. We know we can make them huge, but we don't need to test them to see how big they are. We've done that a few times, but we're not going to test one that could destroy all of Texas.
  4. May 20, 2008 #3
    For starters, you can legitimately doubt that BH creation will occur. The scenarios in which BH will occur and be detectable are considered exotic. So it is extremely unlikely that BH creation will occur anyway. Second, it is extremely unlikely that Hawking evaporation can go wrong. I just can't make a list of all the things that could destroy the planet and that are more likely than "BH are created and they do not evaporate almost instantaneously". Believing BH will be produced and not evaporate is from this point of view schizophrenia : how could the theory be right on the unlikely, improbable prediction (BH created) and wrong on the robust prediction (evaporation) ? Again to be clear : creation is not expected to occur, whereas evaporation not occuring would be a cataclysm in our understanding of physics. But let us admit this insane scenarion anyway... So, third, even considering this crazy scenario where BH are created and they do not evaporate, they would be so incredibly tiny that they can simply not interact with the environement. They would just fly away and that's it. Already at this point we are far away discussing impossible things, please realize this. But let us push on just for fun. Let us assume that besides being created, and not evaporating, they do not fly away. Let us assume that they just sit aroung here. How long will it take them to interact with the environment and start growing bigger, to the point that we could actually be scared ? Much, much, much more than the expected lifetime of our Sun.

    They do, and for good reasons. Physicists calculate and measure probabilities much smaller than a few parts in a billion. If that kind of things were an human attribute, it would be improbable to happen in the entire population of Earth. When we say "negligible", we mean it.
    No way. That would require a bigger machine.
    Theoretically, anything is possible if you have enough time and money. But practically, I do not think we would have any clue hot to make a macroscopic BH. Franckly if we could, it would be worth to make one in orbit around the Sun and experiment with it. If we had the slightest clue how to do that, even in one hundred years from now, you would have quite a few people working on making this happen.
    No, definitely if we destruct ourselves, we have plenty of other ways which are zillion times more likely. Sorry for your theory. But sleep quietly about LHC destrying the world. Think about next time you take your car, which probabilities are the most relevant to spend one's time to evaluate. :smile:
    Last edited: May 20, 2008
  5. May 20, 2008 #4
    Well put humanino, but I can still see the hilarious public hysteria thats coming if anyone ever decides to try. I'm picturing Y2k times a million :rolleyes:
  6. May 23, 2008 #5
  7. Aug 5, 2008 #6
    Safety of world is also based on assumption, that mini black holes
    will evaporate via Hawking radiation. You can find doubts about
    existence of this radiation in Wikipedia. But I have noticed following.
    There is contradiction in Hawking's original paper
    [S. W. Hawking, Commun. math. Phys., 43, 199 (1975),
    (downloadable from Wikipedia)].
    Namely on page 207 is written:
    "no particles on j^{-}" but on page 208 is written:
    "the wave would propagate... out on j^{-}".
    In the "particle description" the wave function corresponds
    to particles. So on page 208 there are particles on j^{-}.
    Last edited: Aug 5, 2008
  8. Aug 5, 2008 #7
    Suppose mini black hole (BH) is created and suppose the Hawking radiation
    isn't working (see doubts in Wikipedia).
    Haw fast this black hole will destroy the Earth?
    Under gravitational attraction BH will fall towards center of the planet.
    Soon BH drops into liquid magma. Because it is liquid, then
    the event horizon will be under pressure. So, particles of magma will be like
    free falling into BH, constantly crossing the event horizon. Because time of free fall
    into BH is very limited, soon the all magma will be sucked into BH.
    The Earth core without support of magma will crush together.
    Even if BH somehow remains on the surface of the planet,
    the event horizon will be under pressure of the Earth atmosphere.
    So, like in case of the magma, the air will very soon disappear.
  9. Aug 6, 2008 #8


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    A black hole created from the mass of 10 protons won't magically have an extremely large gravitational pull just because it's called a 'black hole'.

    If a black hole were created, and if somehow everyone was wrong about black hole radiation, and if this black hole were created completely at rest on earth (as otherwise it would just leave pretty damn fast), then its gravitational pull would be so incredibly tiny that it would be undetectable by anything except LHC detectors.
  10. Aug 6, 2008 #9


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    Staff Emeritus
    Science Advisor

    The entire premise of this thread 'scientists are hoping to create black holes' is wrong. This is not philosophy, thus this thread is done.
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