On 6/3/2016 1:28 AM, Bruce Kellett 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.....)
If the world is a simulation, i.e. is being computed by a Turing
machine, then the computation can implement non-local hidden variables
and violate Bell's inequality in the simulated world (in fact all its
variables would be non-local since locality and spacetime would just be
computed phenomena).
Brent
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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