On 3/9/2014 7:00 PM, LizR wrote:
On 10 March 2014 14:54, meekerdb <[email protected]
<mailto:[email protected]>> wrote:
So exactly how has MWI dealt with this? Everett just sort of said it has
to be that
way, i.e. humans are like measuring instruments and so they make
measurements which
diagonalize their reduced density matrix (but not the whole density
matrix). But
there's not really a theory of consciousness that tells us how it's like a
measuring
instrument AND, even if there were, there's not a theory that tells us why
it's OK
to diagonalize a part of the density matrix, but not all of it, in some
basis we
choose. Note that this is a purely mathematical operation we choose to do
- not
some physical process. Omnes looks at the same mathematical process and
says, once
we've diagonalized the reduced density matrix we've predicted
probabilities, and so
we should be satisfied that one of them is realized and with the predicted
frequency.
I was thinking of decoherence, which I seem to recall iirc was worked out maybe 15 years
after Everett produced his thesis?
If so, this isn't anything specifically to do with consciousness as far as I know; I
assume we should observe whichever part of the multiverse we're entangled, and that
we're entangled with it due to the various quantum interactions that got that version of
us there.
Decoherence is what I described above. It's tracing over the environment variables,
having selected what counts as environment and what as instrument/observer, in order to
get the reduced density matrix and then saying "Obviously we should measure/observe one of
these diagonal values with the proportional probability." So when you get right down to
how the math goes it's pretty close to choosing the Heisenberg cut - except you then say
"and my other selves will measure/observe the other diagonal values" which soothes one's
angst over randomness.
Brent
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