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. 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. 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.
Brent
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