On 16 Jan 2014, at 04:05, Jason Resch wrote:
Hyper determinism makes little sense as a serious theory to me. Why
should particle properties conform to what a computer's random
number generator outputs, and then the digits of Pi, and then the
binary expansion of the square root of 2, all variously as the
experimenters change the knobs as to what determines the spin axis
of the lepton their analyzer measures. Are radioactive decays of
particles really such things that are governed by the behavior of a
selected random source, or alternately, are they really such things
that govern what the digits of Pi or the square root of 2 are?
Yes, that's my point. Price make a logical point, though. But we have
to abandon QM for QM + a lot of extra-information to select one reality.
In that case why not come back to Ptolemeaus. The idea that it is the
sun which moves in the sky is consistent too, even with Newton
physics, if you put enough extra-data in the theory.
With one reality, a quantum computer works only because of extra-
magical boundary conditions.
Bruno
Jason
On Wed, Jan 15, 2014 at 6:13 AM, Bruno Marchal <[email protected]>
wrote:
On 15 Jan 2014, at 11:10, LizR wrote:
On 15 January 2014 22:55, Bruno Marchal <[email protected]> wrote:
On 14 Jan 2014, at 22:04, LizR wrote:
Sorry, I realise that last sentence could be misconstrued by
someone who's being very nitpicky and looking for irrelevant
loopholes to argue about, so let's try again.
Now how about discussing what I've actually claimed, that the time
symmetry of fundamental physics could account for the results
obtained in EPR experiments?
Logically, yes.
But you need "hyper-determinism", that is you need to select very
special boundary conditions, which makes Cramer's transaction
theory close to Bohm's theory.
I'm not sure what you mean by special boundary conditions. The bcs
in an Aspect type experiment are the device which creates the
photons, and the settings of the measuring apparatuses.
The setting of the analyser must be predetermined. And not in the
mechanist sense, where the choice of the analyser is still made by
you, even if deterministically so. With only one branch, you are not
just using irreversibility, but you are using the boundary condition
selecting a branch among all in the universal wave.
These are special but only in that the photons are entangled ...
note that this isn't Cramer's or Bohm's theory (the transaction
theory requires far more complexity that this).
Those are still many-world theories, + some "ugly" selection
principle to get one branch. It is very not "natural", as you have
quasi microsuperposition (appearance of many branches), but the
macro-one are eliminated by ad hoc boundary conditions, which will
differ depending on where you will decide to introduce the
Heisenberg cut. Also, QM will prevent us to know or measure those
boundary conditions, which makes them into (local, perhaps, in
*some* sense) hidden variable theory.
I don't understand the above. The theory is simply QM with no
collapse and with no preferred time direction (it assumes any
system which violates Bell's inequality has to operate below the
level where decoherence brings in the effects of the entropy
gradient). It is both local and realistic, since time symmetry is
"Bell's 4th assumption" - it allows EPR experiments to be local and
realistic (I am relying on John Bell for this information, I
wouldn't be able to work it out myself). So it definitely is a
"hidden variable theory".
Yes, and I am willing to accept it is local. but it is "hyper-
determined". It means that if I chose the setting of the two
analyser in the Aspect experience by looking at my horoscope, that
horoscope was determined by the whole future of the phsyical
universe. Logically possible, you are right, but "ugly", as it is a
selection principle based on boundary conditions. It is "more local"
than Bohm, and it does not need a new potential, but it is sill
using abnormal special data for the "TOE". It is no more a nice and
gentle equation like the SWE, but that same equation together with
tuns of "mega-terra-gigabyte of data".
I think for it to work the system is kept from undergoing
decoherence or any interaction that would lead to MWI branching.
EPR experiments only appear to work for systems that are shielded
from such effects, I think? So there isn't a problem with the MWI -
the whole thing takes place in one branch, with no quantum
interfence etc being relevant. (I believe that EPR experiments lose
their ability to violate Bell's inequality once interactions occur
that could cause MWI branching within the system under
consideration???)
?
Many worlds is far less ad-hoc, imo. There is no Heisenberg cut,
and the boundary conditions does not play any special role, and
indeed they are all realized in the universal wave (and in
arithmetic).
Please explain about the Heisenberg cut. I've heard the term, but
don't know how it relates to EPR experiments.
The Heinsenberg cut is where the wave should collapse in the
Copenhagen QM.
Von Neumann understood well that it is largely arbitrary.
In all "one world theory", you have to justify why the superposition
works so well for the micro-worlds, and disappear for the macro-
world. Using reversiblity, cannot by itself solve that problem.
What works is reversibility and the boundaries conditions. God needs
to know all the detail of the big crunch to program convenably the
big bang, so as making an Aspect result consistent with "one-world",
locality and determinacy.
Have you read Huw Price's book "Time's arrow and Archimedes' Point" ?
No. I know it, as it is often discussed on forums.
I am not convinced, as I tend to not believe in any primitive time
and space, at least when I tend to believe in comp (of course I
*know* nothing).
QM is indeed reversible (in large part), but using this to select
one branch by boundary condition, is still like a form of cosmic
solipsism to me. We can't refute it, and unlike most QM collapse
theories, we can't criticize it from locality and determinacy, but
that does not yet make it convincing compare to MW, and infinitely
more so in the comp frame, where we can't avoid the many "dreams".
Bruno
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