On 25 Jan 2017, at 07:35, Brent Meeker wrote:
On 1/24/2017 8:05 AM, Bruno Marchal wrote:
On 23 Jan 2017, at 20:45, Brent Meeker wrote:
On 1/23/2017 3:23 AM, Bruno Marchal wrote:
On 21 Jan 2017, at 21:39, Brent Meeker wrote:
Phillip Ball's critique of MWI.
It can make sense in a non mechanist theory of mind, but ...
where is that theory? Where is the "Heisenberg cut". (I have not
yet complete the reading of that note, though).
The MWI is not born with Everett, but with the Einstein/Bohr
debate, and eventually with von Neuman collapse of the wave
theory. The collapse of the wave is just a very mysterious
happening, contradicting the SWE,
Born postulated the probability interpretation of the wave-
function in order to give it empirical content. It doesn't
"contradict" anything - it adds a way to get observables from the
SWE.
No problem with this. I am OK with interpreting Bohr that way, but
in his correspondence with Einstein, it is not clear if he still
not believe in the collapse of the wave, which is essentially what
Einstein dislikes, as it the collapse, and the collapse only, when
considered as a physical happening, which introduces a physical
indeterminacy and non-locality, which made no sense in Einstein's
mind.
and invented to suppress the many-worlds which are implied by the
SWE.
It's questionable whether they are implied. To be "a world" means
to be a classical world.
You take the word "world" too much seriously.
You are the one who uses modal logic, which depends on Kripke's idea
of worlds.
That makes my point, because the world of Kripke are only element of a
set on which a binary relation is defined. Kripke and modal world can
represent anything (real worlds, imaginary worlds, situations,
computer states, dreams, computations, or abstract elements use only
to find logical counter-examples. They are not "world" in any physical
or metaphysical sense a priori. Just mathematical tool, which can be
used in metaphysics, depending on our metaphysical or theological
assumption. In Solovay's proof, the world of the Kripke semantics are
numbers, and are not conceive as anything looking like a world.
I am not sure there is any "classical world", except for the
ultimate reality (like a standard model of PA, or SK, ...).
Classicality is still only a local view developed by a local
observer.
That's a solipists definition. The point of classicality is that it
allows intersubjective agreement between observers.
That is the notion of first person plural, and it does not lead to a
classical logic. Classical logic is handy for intersubjective
agreement, but other logic can be handy too, even mandatory in some
context, like the machine observation context.
There is no world at all, if we assume mechanism. A "world" is a
subjective construct by a universal number embedded in infinitely
many computations, and the logic pertaining of what the machine can
predict *cannot* be classical logic, below the substitution level,
and can be classical locally above the substitution level, assuming
the brain works classically.
As Bohr realized having a classical world in which records were
permanent and sharable was essential.
Essential for its dualistic view where the observers are no more
described by quantum mechanics.
Essential in order to do science, to repeat experiments, compare
results, to have beliefs...etc.
The very existence of Everett formulation of QM, or even von Neumann
contradicts this, it seems to me. QM obeys classical logic. Everett
made the physical reality quite classical, with an explanation why
observations looks like not obeying classical logic. Bohr too, but
only by making QM wrong for the macro and/or observer, and that
dualism is incompatible with computationalism, if not any monistic
science.
When Everett try to explain his monistic universal wave theory to
Bohr, Bohr told him that the conversation was terminated.
Bohr was in his late 70's and probably didn't understand Everett's
idea.
OK.
Although there are suggestive arguments no one has yet shown how
classical worlds are implied by QM.
I don't think there are classical physical worlds. Only a classical
immaterial mind, which is the mind of the universal machine looking
at its own functionning just above its substitution level.
?? How can a mind have a substitution level. What do you substitute
for thoughts?
The substitution level of a mind is the substitution level of the
program which implements it. Wherever the machine will look below that
level, the machine will "see" an infinity of different universal
system/computations. That follows from the first six steps of the UD
argument/paradox.
The laws of thought are classical (Boole), but with mechanism this
implies that the laws of physics cannot be classical,
Why not?
Because by incompleteness, the logic of []p & <>t is quantum, on the p
sigma_1.
except for high level description, and that is only a useful
practical simplification.
I think you said it yourself once. It seems you have explained
sometimes ago that we have only "quasi classical" worlds. I prefer
to use "consistent histories" à-la Omnes and Griffith, which are
closer to the machine's computation notion.
Consistent histories are based on projection operators which
"collapse" the wave function.
No problem, as long as the "collapse" is not a physical collapse. The
WM-duplication also show that the individual feels like a collapse of
their 3p state.
Bruno
Brent
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