Thanks. I found this critique by Kastner (who of course says that the
transactional interpretation solves the problem).
https://arxiv.org/ftp/arxiv/papers/1308/1308.4272.pdf
Brent
On 10/30/2022 4:41 PM, Lawrence Crowell wrote:
I remember some issue surrounding this. I do not remember the way it
was resolved, but I do recall that Hobson was considered wrong.
LC
On Saturday, October 29, 2022 at 8:04:35 PM UTC-5 [email protected]
wrote:
On 10/29/2022 6:29 AM, Lawrence Crowell wrote:
On Friday, October 28, 2022 at 10:55:50 PM UTC-5 Bruce wrote:
On Sat, Oct 29, 2022 at 1:42 PM Brent Meeker
<[email protected]> wrote:
On 10/28/2022 6:43 PM, Bruce Kellett wrote:
Look, "ad hoc" is frequently bandied about as a fatal
flaw in any theory. Just as Putin waves about the
nuclear threat: this is just to intimidate the
opposition, it doesn't mean anything more. Any theory
has ad hoc elements, or else it would not be of any
value in explaining our experience. There is always a
theoretical part, and then a collection of elements that
serve to relate the theory to observation. Everything is
ultimately ad hoc, because it is for the particular
purpose of explaining observation.
I think you've stretched it's meaning beyond
recognition. If every theory that is devised to match
experiment is ad hoc then indeed all science is ad
hoc...and the better for it. But there is real ad hockery
that is deserving of criticism.
The real question on the table is what would you take to
be not ad hoc; what would be better than "... measurement
is then not treated in terms of the fundamental dynamics
of the theory." Do you see MWI doing this?
No. MWI takes unitary dynamics of the Schrodinger equation to
be fundamental. But unitary dynamics and the SE are
deterministic, and incompatible with a probabilistic
interpretation. So MWI is not going to be able to give a
completely satisfactory account of measurement since the
outcomes of measurement are inherently probabilistic. So
whatever you do in MWI, measurement is not treated in terms
of the fundamental dynamics of the theory; there is always
some ad hoc element required to make contact with experiment.
In that context MWI, is simply engaging in a double standard
when it criticizes collapse theories as ad hoc.
Bruce
Quantum mechanics deals with the evolution of probability
amplitudes a_i and probabilities are p_i = |a_i|^2. The
probabilities are the trace of the density matrix and the density
matrix by the Schrodinger equation is dρ/dt = [H, ρ], and this
describes the evolution of probabilities. With an actual outcome
the probabilities are no longer applicable due to there being
only one outcome.
LC
Art Hobson has a series of papers on the "measurement problem" in
which he argues that past analyses, by von Neumann and others,
incorrectly ignore non-local entanglement in going from the
density matrix of the system+instrument to the diagonalized
system+instrument representing a mixture. And when this is
correctly accounted for he says the non-local entanglement causes
the measured value (which is random per Born) to be a unique
realization of the eigenvector...no multiple worlds.
SUMMARY AND CONCLUSION
Using only the standard principles of quantum physics, but minus the
collapse postulate, we have shown that quantum state collapse
occurs as a
consequence of the entanglement that occurs upon measurement as
described in
1932 by von Neumann (Equation (4)). The entangled "measurement
state" of a
quantum system and its detector is the collapsed state: It
incorporates the required
perfect correlations between the system and its detector, it
predicts precisely one
definite outcome, and it incorporates the nonlocal properties--the
instantaneous
collapse across all branches of the superposition--that Einstein
showed to be
required in quantum measurements
See attached.
Brent
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