On 26 Feb 2015, at 12:02, Bruce Kellett wrote:
Bruno Marchal wrote:
On 25 Feb 2015, at 23:31, Bruce Kellett wrote:
Bruno Marchal wrote:
On 25 Feb 2015, at 12:28, Bruce Kellett wrote:
In particular one has to solve the basis problem
I disagree. It seems to me that Everett already solved it. The
relative subjective state does not depend on the base.
That is precisely the problem. There are an infinite number of
possible bases for any Hilbert space and the Everett relative
state formulation does not distinguish between them -- but
experience does. Why?
Because when we do an experience, in a lab, or with our eyes, we
*choose* a base. (in the case of our eyes, of course, nature made
the choice of the base for us, through our history).
It is not different than "there are many planet, why are we on
Earth".
That is the problem which is solved by the notion of indexical, and
that computationalism generalizes.
Anthropic arguments simply do not cut it in this case.
I don't use anthropic argument. I say only that the apparent
importance of some base is due to the fact that evolution of living
being has exploited the position base.
What you say here is essentially Bohr's original idea that quantum
phenonema only make sense in relationa to classical measuring devices.
Not really. My argument works with a quantum base too. Similarly, the
UDA works also with a quantum brain.
But the global phenomenon lead to the same subjective experience,
whatever the base is chosen.
The global birds eye view does not change with basis, sure, but the
subjective experience is entirely determined by the basis.
Which one? This statement is ambiguous. The result of an experiment
depends on the choice of the base, but that is equivalent with saying
that the result depends on what we decide to measure, or that a
subjective experience depends of the brain. This is not a problem in
the SWE without collapse. On the contrary, it is the collapse which
forces Bohr to give a special role to the classical reality. Without
collapse, the reality appears classical, but it is an appearance
entirely explained by the wave, and the memory apparatus of the
observer.
If you build a quantum computer, you can choose any base to represent
the orthogonal 0 and 1. Once chosen, you need to stick with them, for
extracting the results, or making interfere relatively to you.
And the theory does not specify a basis so it does not account for
our experience.
?
This is like saying that the brain theory of consciousness is wrong
because you need to pick out one brain to identify one subjective
experience.
You could refute comp by saying that in the WM duplication experience
comp cannot explain to the Washington guy why he resulted being in
Washington. But comp actually explains why that is impossible to
explain. It is necessarily contingent.
The point is that Everett relative state theory explains the collapse,
without throwing in the trash the principles of determinacy, locality,
etc, and that it does not need to single out any special base at all.
All roles of special bases appear from the inside (in-branches)
relative state stories, in wave obeying the SWE.
same with digital mechanism: we don't need to single out any special
universal machine, for the basic ontology, but after that there is a
conflict between all universal machine to give you a next subjective
state, which will depend on some special universal machine, like the
brain, the environment, etc.
Bruno
http://iridia.ulb.ac.be/~marchal/
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