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From: Extropians@extropy.org
Subject: Extropians Digest #94-10-270 - #94-10-274
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Extropians Digest Mon, 17 Oct 94 Volume 94 : Issue 289
Today's Topics:
cats and coyotes [1 msgs]
Challenge to Uploaders [1 msgs]
Interface-ing messages ? [1 msgs]
SCI: Many-Worlds FAQ [1 msgs]
Searle's popgun [1 msgs]
Administrivia:
Note: I have increased the frequency of the digests to four times a day.
The digests used to be processed at 5am and 5pm, but this was too infrequent
for the current bandwidth. Now digests are sent every six hours: Midnight,
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setting your digest size smaller such as 20k. You can do this by addressing
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::digest size 20
-Ray
Approximate Size: 25806 bytes.
----------------------------------------------------------------------
From: freeman@netcom.com (Jay Reynolds Freeman)
Date: Sun, 16 Oct 1994 21:59:37 -0700
Subject: [#94-10-270] cats and coyotes
> [Phil G. Fraering comments on cats and coyotes]
The consensus from experienced cat owners will probably be that
the best solution is to keep cats indoors. Birds and small mammals
will appreciate it, too.
Before you become an ardent coyote-hater, seek carefully for reports
of feral dogs, or of dogs running amok. I'm not saying there is cause to
rule coyotes out, only that feral dogs should be considered a possibility.
There might be a possibility of legal recourse if a pet dog were running
wild and killing other pets.
-- Jay Freeman
------------------------------
From: dasher@netcom.com (Anton Sherwood)
Date: Mon, 17 Oct 1994 00:05:59 -0700
Subject: [#94-10-271] Searle's popgun
Tim Starr claims:
> Just as socialists quit talking about pure socialism and start talking about
> "market socialism" when confronted with Mises' impossibility proof, so do
> AI advocates stop talking about strong AI and start talking about something
> else when confronted with Searle's Chinese Room argument . . .
I missed something. What is the Chinese Room alleged to prove, other than
that if such a Room can be made, vitalism is empirically indistinguishable
from mechanism? Perhaps I don't understand what "strong AI" means.
> Searle pointed out the irrefutable fact that mere syntactic operations per-
> formers lack a key ingredient of the mind: semantic capability. . . .
What is that, if not a subtle kind of symbol-manipulation for a particular
purpose?
Anton Sherwood *\\* +1 415 267 0685 *\\* DASher@netcom.com
------------------------------
From: price@price.demon.co.uk (Michael Clive Price)
Date: Mon, 17 Oct 1994 13:38:19 GMT
Subject: [#94-10-272] SCI: Many-Worlds FAQ
Nick Szabo writes:
> My point here was orthogonal to many-worlds, I suspect. I was
> disputing the alleged "proofs" of Eberhard et. al. that information
> can't be transmitted FTL in EPR, despite FTL transmission of
> correlated states.
The disproof of FTL signalling is orthogonal to many-worlds, as Nick
says, although I find it easiest to see this from that view point.
Many-worlds is a local theory, without FTL (ignoring gravity), which
reproduces all the experimental results of normal quantum theory. It
therefore follows, no matter which interpretation we hold, that no FTL
signalling is possible.
> These proofs rely on the assumption that the EPR
> source is random:
I don't think the randomness or pseudo-randomness of the source is
relevant and in fact confuses the issue by leading folks to start
thinking in classical terms of the source having a definite, though
unknown or hidden, state prior to measurement of the EPR photons. This
is what Bell, Aspect and other showed was not possible.
It is true that the no FTL property of physics is only an assumption,
but it is an assumption consistent with all known facts, including all
the pseudo-paradoxes of quantum theory, so we have no reason for
dropping it.
Here is my many-worlds FAQ entry on EPR, which may or may not be
relevant to the issue that Nick is addressing:
********************
Q28 Does the EPR experiment prohibit locality?
------------------------------------------
The EPR experiment is widely regarded as the definitive gedanken
experiment for demonstrating that quantum mechanics is non-local or
incomplete. We shall see that it implies neither.
The EPR experiment was devised, in 1935, by Einstein, Podolsky and Rosen
to demonstrate that quantum mechanics was incomplete [E]. Bell, in
1964, demonstrated that any hidden variables theory, to replicate the
predictions of QM, must be non-local [B]. QM predicts strong
correlations between separated systems, stronger than any local hidden
variables theory can offer. Bell encoded this statistical prediction
in the form of some famous inequalities that apply to any type of EPR
experiment. Eberhard, in the late 1970s, extended Bell's inequalities
to cover any local theory, with or without hidden variables. Thus the
EPR experiment plays a central role in sorting and testing variants of
QM. All the experiments attempting to test EPR/Bell's inequality to
date (including Aspect's in the 1980s [As]) are in line with the
predictions of standard QM - hidden variables are ruled out. Here is
the paradox of the EPR experiment. It seems to imply that any physical
theory must involve faster-than-light "things" going on to maintain
these "spooky" action-at-a-distance correlations and yet still be
compatible with relativity, which seems to forbid FTL.
Let's examine the EPR experiment in more detail.
So what did EPR propose? The original proposal was formulated in terms
of correlations between the positions and momenta of two once-coupled
particles. Here I shall describe it in terms of the spin (a type of
angular momentum intrinsic to the particle) of two electrons. [In this
treatment I shall ignore the fact that electrons always form
antisymmetric combinations. This does not alter the results but does
simplify the maths.] Two initially coupled electrons, with opposed
spins that sum to zero, move apart from each other across a distance of
perhaps many light years, before being separately detected, say, by me
on Earth and you on Alpha Centauri with our respective measuring
apparatuses. The EPR paradox results from noting that if we choose the
same (parallel) spin axes to measure along then we will observe the two
electrons' spins to be anti-parallel (ie when we communicate we find
that the spin on our electrons are correlated and opposed). However if
we choose measurement spin axes that are perpendicular to each other
then there is no correlation between electron spins. Last minute
alterations in a detector's alignment can create or destroy correlations
across great distances. This implies, according to some theorists, that
faster-than-light influences maintain correlations between separated
systems in some circumstances and not others.
Now let's see how many-worlds escapes from this dilemma.
The initial state of the wavefunction of you, me and the electrons and
the rest of the universe may be written:
|psi> = |me> |electrons> |you> |rest of universe>
on in on
Earth deep Alpha
space Centauri
or more compactly, ignoring the rest of the universe, as:
|psi> = |me,electrons,you>
And
|electrons> = (|+,-> - |-,+>)/sqrt(2)
represents a pair electrons, with the first electron travelling
towards Earth and the second electron travelling towards Alpha
Centauri.
|+> represents an electron with spin in the +z direction
|-> represents an electron with spin in the -z direction
It is an empirically established fact, which we just have to accept,
that we can relate spin states in one direction to spin states in other
directions like so (where "i" is the sqrt(-1)):
|left> = (|+> - |->)/sqrt(2) (electron with spin in -x direction)
|right> = (|+> + |->)/sqrt(2) (electron with spin in +x direction)
|up> = (|+> + |->i)/sqrt(2) (electron with spin in +y direction)
|down> = (|+> - |->i)/sqrt(2) (electron with spin in -y direction)
and inverting:
|+> = (|right> + |left>)/sqrt(2) = (|up> + |down>)/sqrt(2)
|-> = (|right> - |left>)/sqrt(2) = (|down> - |up>)i/sqrt(2)
(In fancy jargon we say that the spin operator in different directions
form non-commuting observables. I shall eschew such obfuscations.)
Working through the algebra we find that for pairs of electrons:
|+,-> - |-,+> = |left,right> - |right,left>
= |up,down>i - |down,up>i
|me> represents me on Earth with my detection apparatus. I shall assume
that we are capable of either measuring spin in the x or y direction,
which are both perpendicular the line of flight of the electrons. After
having measured the state of the electron my state is described as one
of either:
|me[l]> represents me + apparatus + records having measured
x-axis spin and recorded the x-axis spin as "left"
|me[r]> ditto with the x-axis spin as "right"
|me[u]> ditto with the y-axis spin as "up"
|me[d]> ditto with the y-axis spin as "down"
Similarly for |you> on Alpha Centauri. Notice that it is irrelevant
*how* we have measured the electron's spin. The details of the
measurement process are irrelevant. To model the process it is
sufficient to assume that there is a way, which we have further assumed
does not disturb the electron. (The latter assumption may be relaxed
without altering the results.)
To establish familiarity with the notation let's take the state of the
initial wavefunction as:
|psi>_1 = |me,left,up,you>
/ \
/ \
first electron in left second electron in up state
state heading towards heading towards you on
me on Earth Alpha Centauri
After the electrons arrive at their detectors, I measure the spin
along the x-axis and you along the y-axis. The wavefunction evolves
into |psi>_2:
local
|psi>_1 ============> |psi>_2 = |me[l],left,up,you[u]>
observation
which represents me having recorded my electron on Earth with spin left
and you having recorded your electron on Alpha Centauri with spin up.
The index in []s indicates the value of the record. This may be held
in the observer's memory, notebooks or elsewhere in the local
environment (not necessarily in a readable form). If we communicate our
readings to each other the wavefunctions evolves into |psi>_3:
remote
|psi>_2 ============> |psi>_3 = |me[l,u],left,up,you[u,l]>
communication
where the second index in []s represents the remote reading communicated
to the other observer and being recorded locally. Notice that the
results both agree with each other, in the sense my record of your
result agrees with your record of your result. And vice versa. Our
records are consistent.
That's the notation established. Now let's see what happens in the more
general case where, again,:
|electrons> = (|+,-> - |-,+>)/sqrt(2).
First we'll consider the case where you and I have previously arranged
to measure the our respective electron spins along the same x-axis.
Initially the wavefunction of the system of electrons and two
experimenters is:
|psi>_1
= |me,electrons,you>
= |me>(|left,right> - |right,left>)|you> /sqrt(2)
= |me,left,right,you> /sqrt(2)
- |me,right,left,you> /sqrt(2)
Neither you or I are yet unambiguously split.
Suppose I perform my measurement first (in some time frame). We get
|psi>_2
= (|me[l],left,right> - |me[r],right,left>)|you> /sqrt(2)
= |me[l],left,right,you> /sqrt(2)
- |me[r],right,left,you> /sqrt(2)
My measurement has split me, although you, having made no measurement,
remain unsplit. In the full expansion the terms that correspond to you
are identical.
After the we each have performed our measurements we get:
|psi>_3
= |me[l],left,right,you[r]> /sqrt(2)
- |me[r],right,left,you[l]> /sqrt(2)
The observers (you and me) have been split (on Earth and Alpha Centauri)
into relative states (or local worlds) which correlate with the state
of the electron. If we now communicate over interstellar modem (this
will take a few years since you and I are separated by light years, but
no matter). We get:
|psi>_4
= |me[l,r],left,right,you[r,l]> /sqrt(2)
- |me[r,l],right,left,you[l,r]> /sqrt(2)
The world corresponding to the 2nd term in the above expansion, for
example, contains me having seen my electron with spin right and knowing
that you have seen your electron with spin left. So we jointly agree,
in both worlds, that spin has been conserved.
Now suppose that we had prearranged to measure the spins along different
axes. Suppose I measure the x-direction spin and you the y-direction
spin. Things get a bit more complex. To analyse what happens we need
to decompose the two electrons along their respective spin axes.
|psi>_1 =
|me,electrons,you>
= |me>(|+,-> - |-,+>)|you>/sqrt(2)
= |me> (
(|right>+|left>)i(|down>-|up>)
- (|right>-|left>)(|down>+|up>)
) |you> /2*sqrt(2)
= |me> (
|right>(|down>-|up>)i
+ |left> (|down>-|up>)i
- |right>(|down>+|up>)
+ |left> (|down>+|up>)
) |you> /2*sqrt(2)
= |me> (
|right,down> (i-1) - |right,up> (1+i)
+ |left,up> (1-i) + |left,down> (1+i)
) |you> /2*sqrt(2)
= (
+ |me,right,down,you> (i-1)
- |me,right,up,you> (i+1)
+ |me,left,up,you> (1-i)
+ |me,left,down,you> (1+i)
) /2*sqrt(2)
So after you and I make our local observations we get:
|psi>_2 =
(
+ |me[r],right,down,you[d]> (i-1)
- |me[r],right,up,you[u]> (i+1)
+ |me[l],left,up,you[u]> (1-i)
+ |me[l],left,down,you[d]> (1+i)
) /2*sqrt(2)
Each term realises a possible outcome of the joint measurements. The
interesting thing is that whilst we can decompose it into four terms
there are only two states for each observer. Looking at myself, for
instance, we can rewrite this in terms of states relative to *my*
records/memories.
|psi>_2 =
(
|me[r],right> ( |down,you[d]> (i-1) - |up,you[u]> (i+1) )
+ |me[l],left> ( |up,you[u]> (1-i) + |down,you[d]> (1+i) )
) /2*sqrt(2)
And we see that there are only two copies of *me*. Equally we can
rewrite the expression in terms of states relative to *your*
records/memory.
|psi>_2 =
(
( |me[l],left> (1-i) - |me[r],right> (i+1) ) |up,you[u]>
+ ( |me[r],right> (i-1) + |me[l],left> (1+i) ) |down,you[d]>
) /2*sqrt(2)
And see that there are only two copies of *you*. We have each been
split into two copies, each perceiving a different outcome for our
electron's spin, but we have not been split by the measurement of the
remote electron.
*After* you and I communicate our readings to each other, more than four
years later, we get:
|psi>_3 =
(
+ |me[r,d],right,down,you[d,r]> (i-1)
- |me[r,u],right,up,you[u,r]> (i+1)
+ |me[l,u],left,up,you[u,l]> (1-i)
+ |me[l,d],left,down,you[d,l]> (1+i)
) /2*sqrt(2)
The decomposition into four worlds is forced and unambiguous after
communication between the remote systems. Until the two observers
communicated their results to each other they were each unsplit by each
others' remote measurements, although their own local measurements had
split themselves. The splitting is a local process that is causally
transmitted from system to system at light or sub-light speeds. (This
is a point that Everett stressed about Einstein's remark about the
observations of a mouse, in the Copenhagen interpretation, collapsing
the wavefunction of the universe. Everett observed that it is the mouse
that's split by its observation of the rest of the universe. The rest
of the universe is unaffected and unsplit.)
When all communication is complete the worlds have finally decomposed
or decohered from each other. Each world contains a consistent set of
observers, records and electrons, in perfect agreement with the
predictions of standard QM. Further observations of the electrons will
agree with the earlier ones and so each observer, in each world, can
henceforth regard the electron's wavefunction as having collapsed to
match the historically recorded, locally observed values. This
justifies our operational adoption of the collapse of the wavefunction
upon measurement, without having to strain our credibility by believing
that it actually happens.
To recap. Many-worlds is local and deterministic. Local measurements
split local systems (including observers) in a subjectively random
fashion; distant systems are only split when the causally transmitted
effects of the local interactions reach them. We have not assumed any
non-local FTL effects, yet we have reproduced the standard predictions
of QM.
So where did Bell and Eberhard go wrong? They thought that all theories
that reproduced the standard predictions must be non-local. It has been
pointed out by both Albert [A] and Cramer [C] (who both support
different interpretations of QM) that Bell and Eberhard had implicity
assumed that every possible measurement - even if not performed - would
have yielded a *single* definite result. This assumption is called
contra-factual definiteness or CFD [S]. What Bell and Eberhard really
proved was that every quantum theory must either violate locality *or*
CFD. Many-worlds with its multiplicity of results in different worlds
violates CFD, of course, and thus can be local.
Thus many-worlds is the only local quantum theory in accord with the
standard predictions of QM and, so far, with experiment.
[A] David Z Albert, _Bohm's Alternative to Quantum Mechanics_
Scientific American (May 1994)
[As] Alain Aspect, J Dalibard, G Roger _Experimental test of Bell's
inequalities using time-varying analyzers_ Physical Review Letters
Vol 49 #25 1804 (1982).
[C] John G Cramer _The transactional interpretation of quantum
mechanics_ Reviews of Modern Physics Vol 58 #3 647-687 (1986)
[B] John S Bell: _On the Einstein Podolsky Rosen paradox_ Physics 1
#3 195-200 (1964).
[E] Albert Einstein, Boris Podolsky, Nathan Rosen: _Can
quantum-mechanical description of physical reality be considered
complete?_ Physical Review Vol 41, 777-780 (15 May 1935).
[S] Henry P Stapp _S-matrix interpretation of quantum-theory_ Physical
Review D Vol 3 #6 1303 (1971)
***********************
Michael Price price@price.demon.co.uk
------------------------------
From: Leo Barnard
Date: Mon, 17 Oct 1994 16:23:47 +0100 (BST)
Subject: [#94-10-273] Interface-ing messages ?
Greetings....All my mail from the last week has been destroyed :-\
If any one sent any mailings regarding the Interface could they please
send me a new copy , Thankyou .
PS - I am currently organising an event to take place at the Brighton
Art & Technology conference taking place in March 1995 , If anyone is
interested or may have be able to contribute some enthusiasm to the event
please conntact me . There will be two days of general lectures and talks
and a third day which will be dedicated to people working in the field
and will be open to presentations,Installations demonstrations etc
B-)
Leo
lbarnard@gwent.ac.uk
Telematics Representative
------------------------------
From: John K Clark
Date: Mon, 17 Oct 1994 08:58:55 -0700
Subject: [#94-10-274] Challenge to Uploaders
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EdRegis@aol.comon Sun, 16 Oct 1994 in Message #94-10-260 wrote:
>Actually, I view the matter of definition as irrelevant to the
>issue. We know what consciousness is through personal experience
I agree with you about that.
>and we know enough about it, on the basis of that
>experience, to conclude that apples, for example, are not
>conscious
I disagree with you about that , we know nothing about the
personal experience of apples, or anything else. I believe that
apples are not conscious because they don't act conscious, but
then, I believe in the Turing test.
>The challenge is to show that these same computers, or their
>turbo-revved successors, will reproduce consciousness if and
>when they simulate minds
What's the difference between simulated music and real music,
simulated arithmetic and real arithmetic, simulated minds and
real minds?
>For my money, a computer's passing the Turing test, whatever
>else it may prove, doesn't prove the computer is
>conscious in the sense of what *we* experience as consciousness.
What's this "we" business? If your going to be consistent you'd
have to say I am conscious but the consciousness of other people
is unknown. Actually your correct, the Turing test doesn't
rigorously prove anything about consciousness it's just a rule
of thumb but one all of us use every day, even Searle. Nobody
can live their life thinking they are the only conscious being
in the universe.
John K Clark johnkc@well.sf.ca.us
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End of Extropians Digest V94 #289
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