On 15 Dec 2017, at 06:20, Brent Meeker wrote:
On 12/14/2017 6:27 PM, Jason Resch wrote:
I don't see how Wigner's friend presents a problem for Copenhagen.
According to the CI, the wf collapses when the system measured,
which is when the box is opened. What am I missing? The issue of
the cat's memory is a different matter, problematic IMO. AG
The problem is according to the CI, an isolated system evolves
according to the Shrodinger equation, and therefore does not
collapse. But it also says observation causes collapse.
That is not CI. CI always supposed there is a classical realm in
which measurements and observations were made by classical devices.
Wigner toyed with the idea that consciousness was required, but that
was never Bohr's idea of CI. In a sense, decoherence filled in CI
by providing the mechanism of collapse.
I would say that decoherence explains the illusion of a collapse in
the mind of the machine keeping a diary of the results of measurement.
Decoherence is relative entanglement, and the tracing-out by the
relative observers.
The decoherence theory explains that the universe differentiation is
quite speedy, and why macroscopic coherence is hard to be maintained,
although possible for some material, and quantum topology promises
theoretically possible "solid" qubit, etc. Like you said; it is only a
matter or isolation. Now, the lack of isolation makes coherence easy
lost, but that means only the quasi-irreversible lack of interference
with some terms of the universal wave, not their genuine
disappearance, which would contradict linearity, unitarity, well, the
SWE-or DIRAC-or Feynman.
Bruno
Brent
So when you have a conscious observer who is himself part of an
isolated system, from the point of view of another conscious
observer, which rule wins?
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