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.
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.
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.
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.
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 laws of thought are classical (Boole), but with mechanism this
implies that the laws of physics cannot be classical,
Why not?
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.
Brent
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