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Gathering/absorbing Hawking radiation and generating a net surplus of useful energy (not counting what you feed into the black hole) would violate the Second Law of Thermodynamics.

Created by orthonormal on 2015-08-18; known on 2016-01-01

  • orthonormal estimated 80% on 2015-08-18
  • orthonormal said “(Disagreement with a friend, to be resolved only when a physicist we both trust explicitly answers it.)” on 2015-08-18
  • JoshuaZ said “Are you allowed to keep adding matter into the black hole? ” on 2015-08-18
  • JoshuaZ estimated 20% and said “If you are, this essentially just becomes an efficient method of converting mass to energy. No 2nd Law violation there. ” on 2015-08-18
  • PseudonymousUser estimated 5% on 2015-08-20
  • orthonormal said “JoshuaZ, yes, I’m claiming that it cannot be an efficient method of converting mass to energy. My friend’s argument was that you could feed a black hole and use the Hawking radiation as spacecraft thrust.” on 2015-08-20
  • orthonormal changed the deadline from “on 2016-01-01” and changed their prediction from “Gathering Hawking radiation and generating a net surplus of useful energy would violate the Second Law of Thermodynamics.” on 2015-08-20
  • orthonormal said “Changed the prediction to fit my friend’s proposal better. This change should make the claim strictly stronger.” on 2015-08-20
  • JoshuaZ said “I don’t think he’s correct either precisely! Turning that energy into thrust would be very difficult. Maybe if you had a bellshaped area you kept the blackhole and used an electrically charged blackhole to keep it where it should be. ” on 2015-08-20
  • JoshuaZ said “Usable as an energy source != usable as a thrust source.” on 2015-08-20
  • So8res estimated 10% and said “My estimate ignores the “not counting what you feed in” clause, as I don’t understand it. My claim is that you can build a black hole, feed it matter, reflect/absorb radiation, and thus generate thrust.” on 2015-08-20
  • kallman estimated 15% and said “I don’t know about violating the Second Law, but there’s a number of reasons why it’s improbable to be a feasable means of locomotion (especially if you’re dragging the black hole along for the ride…)” on 2015-08-22