3 ms·

I see you're joking, but I believe it's theoretically possible to extract more power from a pseudorandom stream if you can predict it (that is, if you have a ke

I see you're joking, but I believe it's theoretically possible to extract more power from a pseudorandom stream if you can predict it (that is, if you have a key to decrypt) under certain conditions. It's related to Maxwell's demon: if the signal were exciting a large rod, a flat low energy spectrum would roughly correspond to small thermal fluctuations of the rod, which are bounded by some Carnot-like efficiency. If you can perfectly predict the fluctuations though, you can set up a system of oscillating rods coupled additively to it to absorb it's power such that their sum approximates the Fourier spectrum of the rod. This allows you to extract work from the rod as if it were a sinusoidal signal, which does not have to obey the Carnot limit. In practice this effect should be small though (for the case of Wi-Fi power).

jacquesm 11y ago
That's super interesting, thank you for this comment.
- darkmighty 11y ago
  Well thanks for the compliment. But note that thermodynamics is a delicate subject, that was too simple an argument to be exact. I'm still planning to figure out the details of this kind of problem myself. From my light reading it seems the theories for this subject were fully developed only recently actually, namely non-equilibrium thermodynamics and information-theoretic thermodynamics. What I mentioned is a natural extension of information-theoretic arguments to computational hardness assumptions; they're the same assumptions that allow safe encryption methods in spite of them being 'broken' in an information-theoretic sense (which doesn't consider computer limitations). Without those limitations only variants of the one-time pad are secure and public key crypto (which relies on integer factorization hardness) is impossible. Some basic readings if you're interested: https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progress https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progr... https://en.wikipedia.org/wiki/Computational_hardness_assumption https://en.wikipedia.org/wiki/Computational_hardness_assumpt...

jacquesm 11y ago

That's super interesting, thank you for this comment.

darkmighty 11y ago
Well thanks for the compliment. But note that thermodynamics is a delicate subject, that was too simple an argument to be exact. I'm still planning to figure out the details of this kind of problem myself. From my light reading it seems the theories for this subject were fully developed only recently actually, namely non-equilibrium thermodynamics and information-theoretic thermodynamics. What I mentioned is a natural extension of information-theoretic arguments to computational hardness assumptions; they're the same assumptions that allow safe encryption methods in spite of them being 'broken' in an information-theoretic sense (which doesn't consider computer limitations). Without those limitations only variants of the one-time pad are secure and public key crypto (which relies on integer factorization hardness) is impossible. Some basic readings if you're interested: https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progress https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progr... https://en.wikipedia.org/wiki/Computational_hardness_assumption https://en.wikipedia.org/wiki/Computational_hardness_assumpt...