On 11/15/2017 3:11 AM, Bruce Kellett wrote:
On 15/11/2017 3:12 pm, Brent Meeker wrote:
On 11/14/2017 7:46 PM, Bruce Kellett wrote:
On 15/11/2017 12:49 pm, Russell Standish wrote:
On Wed, Nov 15, 2017 at 11:05:22AM +1100, Bruce Kellett wrote:
One of the strongest arguments for MWI was that it eliminates the
concept of
a conscious observer from the interpretation of quantum mechanics.
I disagree. The strongest argument is that it removes the need for a
mysterious nonunitary physical collapse process (that may or may not
be driven by a conscious observer).
I said "one of the strongest"! I know that you want to define QM
from the idea of observer moments. I don't think that this will
work, and the usual consensus is that one of the strengths of MWI is
the elimination of the conscious observer.
A conscious observer (or rather just observer, really) is still
required to define the branches of the MWI, be that mediated by Zeh's
decoherence process, or otherwise. To eliminate observers entirely
requires solving the preferred basis problem without reference to an
observer or observation.
That is not true. The basis problem is solved by Zurek's
einselection -- the preferred basis is the one that is stable
against further decoherence. Observers have nothing to do with it.
In Zurek's account, it is the fact that the results of interactions,
be they measurements or not, are recorded multiple times in the
environment via decoherence, that is the mark of an irreversible
quantum event.
And "recorded" may not bring the right picture to mind. It is
recorded even if the information is radiated away into space.
True. The loss of interference due to radiation of IR photons from
buckeyballs means that information does not have to be 'recorded' in a
concrete sense -- it just has to be available somewhere, even if
recovery is not practicable.
The future light cone is part of the environment. But this makes me
wonder if there are degrees of this entanglement information. Even
though there are lot of copies of Alice's results in the immediate
vicinity, at a distance of few billion light years the information is
spread very thin, so there is uncertainty as to whether it is
entangled or not at that distance.
There is no distance parameter in the wave function for entanglement!
So distance makes no difference.
But decoherence is a statistical effect. If the probability of
interacting with the wave function at great distance becomes very small,
then decoherence is operationally ineffective - you can't, at that
distance, recover enough information to say which way Alice's
measurement turned out. And the reason for that (maybe) is that the
foliation of spacetime has too much uncertainty over that interval.
Maybe this is empirically ruled out by the lensing of distant
galaxies...I'll have to think about it.
Brent
So, if you are sufficiently far away, is there no longer any fact of
the matter about which result Alice got? This might be a connection
to the quantization of spacetime, since at sufficiently time-like
separated points the propagation of from one superspace foliation to
another must satisfy an uncertainty principle.
Why? I don't see a particular connection here.
Bruce
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