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> I think there are more. Like radiation from evaporating black holes. Evaporating black holes? Yes, if you are willing to wait a very, very long time, and ha

> I think there are more. Like radiation from evaporating black holes. Evaporating black holes? Yes, if you are willing to wait a very, very long time, and have collectors over a large area. However, if you want to get stuff done before your protons evaporate, you could instead throw matter into a black hole, thus increasing its mass. The radiation given off by the accretion disc is substantial, and can be collected... over a large area. IIRC, the mass-to-energy efficiency is something like 40%, which is really good. They are a little difficult to set up however...

naasking 5y ago
I mean, we're talking about timescales and construction projects like Dyson spheres. It's entirely feasible that people with such technology could create microscopic black holes that evaporate quickly for these purposes. Hawking radiation at this scale is substantial.
- ansible 5y ago
  Ah, yes, I do recall reading about that somewhere. That is an interesting prospect, with a very high mass-to-energy efficiency. Of course it requires careful management of inflowing matter. And you can shut if down if needed by stopping the inflow, assuming you have enough stored energy to recreate the micro black hole sometime later.
  - naasking 5y ago
    You'll probably enjoy this video: https://youtu.be/EzZGPCyrpSU https://youtu.be/EzZGPCyrpSU Good channel too.
- kragen 5y ago
  A Dyson sphere is technically possible without any new physics with a few decades of work. By contrast, while we have the physics to analyze how black holes much smaller than a proton would behave, we have no plausible way to go about making one.
  - naasking 5y ago
    > A Dyson sphere is technically possible without any new physics with a few decades of work Not a chance. I disagree 100%. The materials science and orbital mechanics for coordination alone are way beyond our capabilities.
    - lsparrish 5y ago
      It's just a bunch of automated drones flying in formation. Trying to calculate their orbits ahead of time in any kind of detail would be a fool's errand, instead we'd just use solar light pressure to steer them as needed (they would be very thin, there's no point to making them thick). With really thin sails (0.78 g/m^2) they don't even need to orbit, as they can use light pressure to compensate for gravity (what Robert Forward termed a 'statite'). The light they reflect hits other sails on the other side, but this isn't a problem if they are distributed uniformly.
    - emteycz 5y ago
      Dyson sphere as conceived by Dyson himself is a swarm of orbiting objects, not a literal sphere around a star (that's Star Trek interpretation). We could start sending out solar panels to orbit the Sun today, and start adding space stations later this/next decade.
      - naasking 5y ago
        It doesn't count as a Dyson swarm until it captures a large percentage of the sun's output. As I said, that science and the computational power needed to coordinate those kinds of orbital mechanics are beyond us.
        kragen 5y ago
        You'll see.
        emteycz 5y ago
        It doesn't all have to be at a single distance from the Sun. Some objects can be as far as Earth is and other objects can be at Mars level, at Merkur level or wherever else. There's plenty of space for this to be too hard.
- deleted 5y ago
  [deleted]
marcosdumay 5y ago
I wonder how practical it is to sustain right-sized artificial black holes. Small ones should irradiate much more.
potiuper 5y ago
Existing proposals use a plumb bob mechanism or directed light traversing the ergosphere in analogy with sound amplification via linear or in this case rotational energy transfer rather than relying on the feasibility of a complete sphere to absorb any randomly directed radiation from the interior or accretion disk: https://news.ycombinator.com/item?id=30402679 https://news.ycombinator.com/item?id=30402679

naasking 5y ago

I mean, we're talking about timescales and construction projects like Dyson spheres. It's entirely feasible that people with such technology could create microscopic black holes that evaporate quickly for these purposes. Hawking radiation at this scale is substantial.

ansible 5y ago
Ah, yes, I do recall reading about that somewhere. That is an interesting prospect, with a very high mass-to-energy efficiency. Of course it requires careful management of inflowing matter. And you can shut if down if needed by stopping the inflow, assuming you have enough stored energy to recreate the micro black hole sometime later.
- naasking 5y ago
  You'll probably enjoy this video: https://youtu.be/EzZGPCyrpSU https://youtu.be/EzZGPCyrpSU Good channel too.
kragen 5y ago
A Dyson sphere is technically possible without any new physics with a few decades of work. By contrast, while we have the physics to analyze how black holes much smaller than a proton would behave, we have no plausible way to go about making one.
- naasking 5y ago
  > A Dyson sphere is technically possible without any new physics with a few decades of work Not a chance. I disagree 100%. The materials science and orbital mechanics for coordination alone are way beyond our capabilities.
  - lsparrish 5y ago
    It's just a bunch of automated drones flying in formation. Trying to calculate their orbits ahead of time in any kind of detail would be a fool's errand, instead we'd just use solar light pressure to steer them as needed (they would be very thin, there's no point to making them thick). With really thin sails (0.78 g/m^2) they don't even need to orbit, as they can use light pressure to compensate for gravity (what Robert Forward termed a 'statite'). The light they reflect hits other sails on the other side, but this isn't a problem if they are distributed uniformly.
  - emteycz 5y ago
    Dyson sphere as conceived by Dyson himself is a swarm of orbiting objects, not a literal sphere around a star (that's Star Trek interpretation). We could start sending out solar panels to orbit the Sun today, and start adding space stations later this/next decade.
    - naasking 5y ago
      It doesn't count as a Dyson swarm until it captures a large percentage of the sun's output. As I said, that science and the computational power needed to coordinate those kinds of orbital mechanics are beyond us.
      - kragen 5y ago
        You'll see.
      - emteycz 5y ago
        It doesn't all have to be at a single distance from the Sun. Some objects can be as far as Earth is and other objects can be at Mars level, at Merkur level or wherever else. There's plenty of space for this to be too hard.
deleted 5y ago
[deleted]

marcosdumay 5y ago

I wonder how practical it is to sustain right-sized artificial black holes. Small ones should irradiate much more.

potiuper 5y ago

Existing proposals use a plumb bob mechanism or directed light traversing the ergosphere in analogy with sound amplification via linear or in this case rotational energy transfer rather than relying on the feasibility of a complete sphere to absorb any randomly directed radiation from the interior or accretion disk: https://news.ycombinator.com/item?id=30402679 https://news.ycombinator.com/item?id=30402679