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  1. Standard memberDeepThought
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    09 Apr '19 22:16
    @humy
    Other than the difficulty in getting there I don't see why not. The probe would need to be proof against significant tidal forces though.
  2. Standard memberDeepThought
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    09 Apr '19 22:27
    @sonhouse
    It's multiples of the Schwartzschild radius that matter, this happens really close to the event horizon so you'd need to be far closer.

    I was going on what it said in the Wikipedia article, so good spot. The spectrum is blackbody, which means some of the emitted particles will have very high energy at large distances from the black hole. There'll be a few very hard gamma rays. The thing with ultra-relativistic electrons is that we don't need a huge flux to be able to detect them.
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    10 Apr '19 06:04
    @deepthought said
    @humy
    Other than the difficulty in getting there I don't see why not. The probe would need to be proof against significant tidal forces though.
    Thanks for that conformation.
    I will now work on my personal plans to get there...
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    10 Apr '19 06:135 edits
    I have just one more question:
    If you put a space station in orbit around a black hole so that it is constantly arbitrarily close to the event horizon (and design it to deal with the tidal forces), can Hawking radiation be sufficiently intense there to make it practical for the space station to constantly collect it (via solar panels?) to keep the space station sustainably powered up? Can the space station be so positioned so the intensity of radiation it gets from it is, say, about 1/10 of the solar constant currently radiation on Earth!? (I think that power density but not much lower should make it practical)
  5. Standard memberDeepThought
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    10 Apr '19 18:091 edit
    @humy said
    I have just one more question:
    If you put a space station in orbit around a black hole so that it is constantly arbitrarily close to the event horizon (and design it to deal with the tidal forces), can Hawking radiation be sufficiently intense there to make it practical for the space station to constantly collect it (via solar panels?) to keep the space station sustainably powe ...[text shortened]... rently radiation on Earth!? (I think that power density but not much lower should make it practical)
    Interesting question. I'm not sure, different accelerated frames see different particle contents due to the Unruh Effect (see Wikipedia). It might have to be hovering. An orbit is an inertial frame so it could be it sees the same flux as the asymptotic observer, but blue shifted due to orbital speed. Give me a couple of days and I'll see if I can unravel it.
  6. Standard memberDeepThought
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    11 Apr '19 05:45
    @humy said
    I have just one more question:
    If you put a space station in orbit around a black hole so that it is constantly arbitrarily close to the event horizon (and design it to deal with the tidal forces), can Hawking radiation be sufficiently intense there to make it practical for the space station to constantly collect it (via solar panels?) to keep the space station sustainably powe ...[text shortened]... rently radiation on Earth!? (I think that power density but not much lower should make it practical)
    I should have thought of this earlier. The orbit is not possible, the last circular orbit is at 1.5 Schwartzschild radii, the so called photon sphere - assuming an uncharged non-rotating black hole. So to maintain the orbit you've specified would require power and the spacestation would be in an accelerated frame.
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    11 Apr '19 12:37
    @deepthought said
    I should have thought of this earlier. The orbit is not possible, the last circular orbit is at 1.5 Schwartzschild radii, the so called photon sphere - assuming an uncharged non-rotating black hole. So to maintain the orbit you've specified would require power and the spacestation would be in an accelerated frame.
    but could my idea still work with an elliptical orbit without the space station having to create its own acceleration by powering some kind of propulsion system?
  8. Standard memberDeepThought
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    11 Apr '19 12:53
    @humy said
    but could my idea still work with an elliptical orbit without the space station having to create its own acceleration by powering some kind of propulsion system?
    Elliptical orbits are possible. I've been meaning to try to understand the Unruh effect for a while so I'll give it some thought.
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