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Questions about black holes for a fictional story

  1. Apr 13, 2009 #1
    The short version: Is it possible to engineer anything useful with black holes in our universe?

    The long version:

    I'm working on making the backstory for a fiction I've been thinking about, and I'd like to get a better understanding of theoretical black hole physics for that story.

    The way I understand black holes so far is that they have a position, a mass, a rotation vector (including speed), and a charge. They also eject (hawking) radiation effectively as heat, as a way of expressing entropy thanks to quantum particle interactions. The rate this hawking radiation escapes is fairly static compared to the mass of the black hole, meaning that small black holes can lose their entire mass quickly compared to larger black holes which can take longer to lose all their mass than the heat death of the rest of the universe.

    My questions:

    1. Can hawking radiation be directional at all, or is it only expressed as a temperature around a black hole with completely random output?

    2. (related to 1) Is it possible for hawking radiation to impart any kind of velocity on a black hole, or are the effects of the radiation completely isolated from what is inside the event horizon?

    3. Is it possible for any quantum tunneling or similar effects to target anything inside a black hole? Put in other words, if quantum particles involved in a black hole's interactions can force something out of the black hole, can a similar effect started out of a black hole have an effect inside?

    4. Is there any theoretical use for hawking radiation? If a black hole can act as a "heat battery" outliving the rest of the output of the universe, could that long-stored heat energy purchased at great expense be used to lengthen the theoretical lifespan of the presence of solid matter in the universe, even if entropy takes it's toll the entire time? Would it ever be enough energy to maintain an orbit around a large black hole for any amount of matter?

    5. Is there a maximum possible value for the charge a black hole can hold? Would this be enough for two or more long-lasting black holes to hold eachother out of range of their respective event horizons for a long period of time? Or would the same effect prevent further charged particles from entering the event horizon in the first place?

    Basically, I'm wondering how a society/intelligence that was thinking about the extremely long term could possibly use black holes as engines to "refresh" matter and thus information for the maximum amount of time. Are black holes a viable way of "paying" entropy in order to stay in the game of existence longer than would otherwise be possible? Can one "aim" a black hole's facing or position using any outside effect, or are they totally isolated from anything we can affect behind the event horizon?

    Thanks for any input!

    Ryan Fenton
  2. jcsd
  3. Apr 14, 2009 #2


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  4. Apr 14, 2009 #3
    Thanks for the link!

    Hmmm... That method requires too much matter still in existence - I'm looking for a possible plausible way to extend the existence of matter in the universe, using the extremely long-lasting radiation from super-massive black holes, which should outlast the existence of matter by several orders of magnitude.

    Ryan Fenton
  5. Apr 14, 2009 #4


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  6. Apr 14, 2009 #5
    Entertaining, certainly. I'm thinking more along the lines of those in that tale who view the black hole as a black box - a giant lens that used to reflect the light of the stars, already burnt out. What aspects can be used as a tool, or what prevents that? I'm trying to rule out anything prevented by entropy, or the laws of black hole physics to start - but I'm no trained physicist.

    One thing that tale likely got wrong though was the meaningfulness of the information coming out of the hawking radiation. It's my understanding that such an act is effectively boiling matter and pulling single bits of radiation out at a time, at random - any matter than had gone in would long ago mixed together like in a (bose-einstein) condensate, all on top of eachother, then pulled apart piecemeal.

    Ryan Fenton
  7. Apr 15, 2009 #6
    Our science and understanding of Black Holes are limited at best, for now, but in the future we might find some kind of use for them. Remember, this is far into the future, we might not even find a way to use them for anything at all, but it is nice to draem =)
  8. Apr 15, 2009 #7
    Indeed, and it is nice to be able to craft tales as accurately as possible to inspire further exploration and wonderlust for what is possible.

    Ryan Fenton
  9. Apr 16, 2009 #8


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    I think you could weave a tail about the tidal tails left by a black hole. How would sentient beings interpret those effects as they evolved"
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