From: scerir (scerir@libero.it)
Date: Wed Nov 27 2002 - 10:14:36 MST
gts:
> [...] under the Many Worlds interpretation of
> QM, the observer of an experiment with n possible
> outcomes splits into n different alternates at the
> moment that the measurement changes the state of
> the observer(s), such that each alternate observer
> is created in a different state [...]
At the very foundation of the MWI there is the RSI
('relative state' interpr., by H. Everett, 1956) which
states that there does not, in general, exist anything
like a single state for one subsystem of a *composite*
system, because subsystems do not possess states that
are independent of the states of the remainder of the
system.
So that the subsystem states are generally
*correlated* with one another. One can arbitrarily
choose a state for one subsystem, and be led to the
*relative* state for the remainder.
Thus we are faced with a fundamental *relativity* of
states, which is implied by the *formalism* of composite
systems. And it is meaningless to ask the *absolute*
state of a subsystem: one can only ask the state *relative*
to a given state of the remainder of the system.
Note that the 'coupling' or the 'entangling'
of these 'relative' states (in other terms: the
splitting, in case of quantum superposition of
'relative' states) comes out directly (and just)
from the RSI formalism.
Note, also, that the RSI speaks of 'compositions'
of 'subsystems', which is different from and more
general than 'measurements' by observers.
And note also that in the RSI there is only *one*
physical subsystem representing the observer.
Yet there is no *single* and *unique* state
of the observer (treated as physical subsystem).
That is because the single observer state
splits, branches into a number of different
states, which are (nothing more and nothing less
than) different (and orthogonal) *memory* states
inside, within the single observer's *mind*.
Reality as memory.
In the RSI the branching does not continue
indefinitely, but must stop at a point limited
by the capacity of the memory of the observer.
To overcome many limitations of RSI de Witt invented
the 'strong' MWI. Which is rather messy because
de Witt did not explain whether the 'splitting'
is triggered just by a 'measurement' or by a mere
'interaction' between quantum systems.
"The universe is constantly splitting into a stupendous
number of branches, all resulting from the MEASUREMENT
like INTERACTIONS between its myriads of components.
Moreover, EVERY QUANTUM TRANSITION taking place on
every galaxy, in every remote corner of the universe
is splitting OUR LOCAL world into myriads of copies
of itself" he wote. Eh?
So: just measurements (irreversible) or also quantum
interactions (not irreversible) can cause the splitting
of the worlds? [Imo quantum interaction could also cause
a sort of de-splitting, or fusion of worlds, because of the
unavoidable interference].
s.
"I suspect that Everett and de Witt wrote as if
instrument readings were fundamental only in
order to be intelligible to specialists in quantum
measurement theory."
- John Bell
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