Re: wave function collapse

[Bruno Marchal]

Richard,

Bruno,
I do not find Deutsch's introduction of a rational decision maker  
convincing
e.g.: http://arxiv.org/ftp/quant-ph/papers/9906/9906015.pdf
nor Wallaces elaboration on that theme
e.g.: http://arxiv.org/pdf/0906.2718v1.pdf.

My belief is that a rational decision maker, somewhat like a god,
would following Leibniz, always chose the best quantum state in any  
interaction
to become physical in a single universe. In fact that seems to be  
exactly what
Wallaces rational decision maker does. I think Deutsch has snookered  
us all.
Richard

I don't want to be technical about this, as I "believe" in the many  
dreams at the start. By comp they are just the search of existing or  
non existing solution to diophantine equation, or arithmetical problem.

But technically, from some of its paper at least, Wallace seems to me  
the closer to comp Everettian, i.e. closer to the kind of physics  
which has to emerge from the distribution of the possible dreams/ 
persons in arithmetic, as implied by the comp assumption.

The comp mind-body problem forces us to mega-generalizes Everett, on  
the whole of the arithmetical truth, and physics is "reduced" to  
arithmetic, like the carbon-based biology can be said to be be reduced  
to chemistry today.

Bruno




On Mon, Oct 29, 2012 at 11:28 AM, Bruno Marchal <marc...@ulb.ac.be>  
wrote:
Hi Richard,

On 28 Oct 2012, at 21:01, Richard Ruquist wrote:

Bruno, But it seems that the Gleason Theorem assigns probabilities  
to
the different universes in the multiverse that are not there in
Everett's MWI in the first place. Richard


?
I don't see that, nor why you say so. can you elaborate? Gleason  
theorem
just makes unique the usual Born rule, and justify a literal  
reading of the
quantum amplitude as relative (infinite) proportions.
It is quite similar to the Deutsch Hayden justification, in decision
theoretical terms, of such amplitude reading, in the Heisenberg  
picture.

Bruno





On Sat, Oct 27, 2012 at 9:46 AM, Bruno Marchal <marc...@ulb.ac.be>  
wrote:


On 26 Oct 2012, at 15:52, Richard Ruquist wrote:

Well Bruno,

If the "measure problem" (which I take to be the assignment of
probabilities) is intrinsic to Everett's MWI, does that not  
amount to
negating it?



Why? I think that it is beautifully solved by Gleason theorem,  
for the
Hilbert space of dim bigger or equal to 3.



I did not suggest that it negated comp, which is what you
responded to.



I think comp will confirms Everett QM, and this would make our  
sharable
human or animal substitution level very plausibly at the Heisenberg
uncertainty level, this for surviving even a long run, without  
detecting
any
difference.

In that case, the Gleason solution will be the solution for comp.  
For
this
the X and Z logics (alreeady extracted) must conforms to some  
desiderata,
already expressed by von Neumann, for a quantum logic, and which  
is that
mainly it defines the searched measure.

I m not sure I can understand string theory or any fundamental QM  
without
Everett.

I agree that the idea that we are multiplied by infinities at each
instant
is not attractive, but science is not wishful thinking, and  
besides, I
don't
take any theory too much seriously (we don't know). I also know  
that
different theories can happen to be equivalent.

Of course, to be sure, comp has also many attractive features,  
mainly its
conceptual simplicity and naturalness. It really explains almost  
why
there
is something instead of nothing, as it assumes only 0 and the  
successor
and
the very simple laws, and explain from that how that very  
explanation
emerges in some collection of stable numbers' dream.

Bruno






Richard

On Fri, Oct 26, 2012 at 9:35 AM, Bruno Marchal <marc...@ulb.ac.be>
wrote:


Richard,

On 25 Oct 2012, at 18:42, Richard Ruquist wrote:

Bruno,

Doesn't the Gleason Theorem negate MWI by assigning  
probabilities?
Richard




On the contrary. Gleason theorem solves the "measure problem"  
intrinsic
in
the Everett MWI, it makes the probabilities into comp (or  
weakening)
first
person indeterminacies.

Unfortunately, comp necessitates a version of Gleason theorem  
for all
comp
states, not just the quantum one, as the quantum law must be  
derived
from
the 1p indeterminacies, occurring in arithmetic.

The advantage is that comp provides the theory of both quanta and
qualia
(and a whole theology actually).
Unfortunately, it is not yet clear if those quanta behave in a
sufficiently
quantum mechanical way, like making possible quantum computers,
hydrogen,
strings may be, etc.

Bruno





On Thu, Oct 25, 2012 at 9:38 AM, Bruno Marchal <marc...@ulb.ac.be 
>
wrote:




On 24 Oct 2012, at 19:53, meekerdb wrote:

On 10/24/2012 4:31 AM, Bruno Marchal wrote:


On 23 Oct 2012, at 14:50, Roger Clough wrote:

Hi meekerdb

There are a number of theories to explain the collapse of the  
quantum
wave
function
(see below).

1) In subjective theories, the collapse is attributed
to consciousness (presumably of the intent or decision to make
a measurement).


This leads to ... solipsism. See the work of Abner Shimony.




2) In objective or decoherence theories, some physical
event (such as using a probe to make a measurement)
in itself causes decoherence of the wave function. To me,
this is the simplest and most sensible answer (Occam's Razor).


This is inconsistent with quantum mechanics. It forces some  
devices
into
NOT
obeying QM.


No, it's only inconsistent with a reified interpretation of  
the wf.
It's
perfectly consistent with an instrumentalist interpretation.
Decoherence
is
a prediction of QM in any interpretation.  It's the  
einselection
that's
a
problem.






But instrumentalism is just an abandon of searching  
knowledge. There
is
no
more what, only how.
An instrumentalist will just not try to answer the question of
betting
if
there is 0, 1, 2, ... omega, ... universes.

And the einselection is not a problem at all, in QM + comp.  
It is
implied.
And, imo, the QM corresponding measure problem is solved by  
Gleason
theorem
(basically).

And then, keeping that same 'everything' spirit, the whole QM  
is
explained
by comp. We have just to find the equivalent of "Gleason  
theorem" for
the
"material hypostases".

Bruno








3) There is also the many-worlds interpretation, in which  
collapse
of the wave is avoided by creating an entire universe.
This sounds like overkill to me.


This is just the result of applying QM to the couple  
"observer +
observed".
It is the literal reading of QM.




So I vote for decoherence of the wave by a probe.


You have to abandon QM, then, and not just QM, but comp too  
(which
can
only
please you, I guess).

Bruno


http://iridia.ulb.ac.be/~marchal/



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