On Friday, 3 June 2016, Bruce Kellett <[email protected]> wrote:
> On 3/06/2016 4:39 pm, Brent Meeker wrote: > > Scott Aaronson's blog on his debate with Roger Penrose is probably of > interest to the list: > > * “Can computers become conscious?”: My reply to Roger Penrose* > *June 2nd, 2016* > > > *A few weeks ago, I attended the Seven Pines Symposium on Fundamental > Problems in Physics outside Minneapolis, where I had the honor of > participating in a panel discussion with Sir Roger Penrose. The way it > worked was, Penrose spoke for a half hour about his ideas about > consciousness (Gödel, quantum gravity, microtubules, uncomputability, you > know the drill), then I delivered a half-hour “response,” and then there > was an hour of questions and discussion from the floor. Below, I’m sharing > the prepared notes for my talk, as well as some very brief recollections > about the discussion afterward. (Sorry, there’s no audio or video.) I > unfortunately don’t have the text or transparencies for Penrose’s talk > available to me, but—with one exception, which I touch on in my own > talk—his talk very much followed the outlines of his famous books, The > Emperor’s New Mind and Shadows of the Mind. *Read the rest at > http://www.scottaaronson.com/blog/ > > > This is interesting, and I would like to spend more time on it, but one > thing struck me as I was leafing through.... > > "The third place where I part ways with Roger is that I wish to maintain > what’s sometimes called the Physical Church-Turing Thesis: the statement > that our laws of physics can be simulated to any desired precision by a > Turing machine (or at any rate, by a probabilistic Turing machine). That > is, I don’t see any compelling reason, at present, to admit the existence > of any physical process that can solve uncomputable problems. And for me, > it’s not just a matter of a dearth of evidence that our brains can > efficiently solve, say, NP-hard problems, let alone uncomputable ones—or of > the exotic physics that would presumably be required for such abilities. > It’s that, even if I supposed we could solve uncomputable problems, I’ve > never understood how that’s meant to enlighten us regarding consciousness." > > This relates to my current obsession with the universal applicability of > Bell's theorem (and other inequalities such as that of CHSH). Consider the > statement of the Church-Turing thesis: "the statement that our laws of > physics can be simulated to any desired precision by a Turing machine (or > at any rate, by a probabilistic Turing machine)". This is not true for > Bell-type experiments on entangled particle pairs. To be more precise, the > correlations produced from measurements on entangled pairs at spacelike > separations cannot be reproduced by any computational process. A recent > review (arXiv: 1303.2849, RMP 86 (2014) pp419-478) points out that > violations of the Bell inequalities can be taken as clear confirmation the > separated experimenters making the measurements had not communicated: if > they had communicated during the experiment then the inequalities would be > satisfied. The corollary is that there is no possible local computational > algorithm (not involving recourse to the effects of quantum entanglement) > that can produce correlations that violate the Bell inequalities. In other > words, the laws of physics cannot be simulated to any desired precision by > a Turing machine. (I don't think solving NP problems has anything much to > do with it.....) > > This is where one looks for a non-Turing-emulable aspect of physics. This > may or may not undermine AI, but it certainly sinks mathematical universe > proposals such as those by Tegmark or Marchal. > A simpler example of non-computability is true (as opposed to pseudo-) randomness. If quantum mechanics is correct, true randomness is a feature of the universe. But while a computer cannot be programmed to give a true random number, an observer in a deterministically branching virtual world will experience true randomness because there is no way he - or even an omnipotent being - can know which branch he will end up in. This has been discussed at length by Bruno with his duplication thought experiments, and also by Tegmark. -- Stathis Papaioannou -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
