On 04 Jun 2016, at 01:28, Bruce Kellett wrote:
On 4/06/2016 4:16 am, Brent Meeker wrote:
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).
Sure, Bell's theorem only rules out local hidden variables. If you
simulate non-local hidden variables (i.e., get the separated
experimenters to communicate non-locally), then of course you can
reproduce the quantum correlations. But I was under the impression
that the computationalist goal was to eliminate non-locality.
Separated experimenters, with as much computing power as necessary,
cannot simulate the quantum correlations by performing only local
computations.
You can simulate the whole (multiversial) structure, and the observers
will find that from their perspective, Bell's inequality are violated.
From outside, we can see (like Everett saw) that it is just a case of
self-duplication FPI. (Which brings us back to the preceding thread of
course).
Bruno
Bruce
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