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.
Bruce
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