wedrifid comments on A problem with Timeless Decision Theory (TDT) - Less Wrong

36 Post author: Gary_Drescher 04 February 2010 06:47PM

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Comment author: loqi 05 February 2010 04:37:20AM *  0 points [-]

Gary postulated an infallible simulator, which presumably includes your entire initial state and all pseudorandom algorithms you might run. Known quantum randomness methods can only amplify existing entropy, not manufacture it ab initio. So you have no recourse to coinflips.

EDIT: Oops! pengvado is right. I was thinking of the case discussed here, where the random bits are provided by some quantum black box.

Comment author: wedrifid 05 February 2010 05:38:01PM 0 points [-]

EDIT: Oops! pengvado is right. I was thinking of the case discussed here, where the random bits are provided by some quantum black box.

Does putting the 'quantum' in a black box change anything?

Comment author: loqi 05 February 2010 07:09:25PM *  0 points [-]

Not sure I know which question you're asking:

  1. A black box RNG is still useless despite being based on a quantum mechanism, or
  2. That a quantum device will necessarily manufacture random bits.

Counterexamples to 2 are pretty straightforward (quantum computers), so I'm assuming you mean 1. I'm operating at the edge of my knowledge here (as my original mistake shows), but I think the entire point of Pironio et al's paper was that you can verify random bits obtained from an adversary, subject to the conditions:

  • Bell inequality violations are observable (i.e., it's a quantum generator).
  • The adversary can't predict your measurement strategy.

Am I misunderstanding something?

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