Answers to Part III
These were an exercise in Born's Rule.
The next questions depend on linearity
and on understanding the Dirac notation;
e.g., knowing that if |1> is an
eigenstate of A, then its eigenvalue is 1, so that A|1>=|1>.
The final two questions concern understanding the inner product and the
concept of an eigenstate.
Question 15
relates to the "many minds" and also to quantum logic.
For suppose
that alpha and beta are the two possible results
of a measurement
and that |psi>
is the after-measurement state.
And suppose Q is the question:
"Do you believe that the measurement had a
definite result in this state?"
Where Q=1 means "yes" and Q=0 means "no".
Then in the |alpha>
eigenstate, Q=1; also in the |beta> eigenstate.
But then in
the superposition |psi>,
where
there is no definite result,
we find that here too Q=1.
So the
linearity of QM seems to entail that we are bound to be deceived,
having to
believe in definite results when there are none.
That is the foundation for
"many minds".
Quantum logic would make the superposed state |psi>
represent the
disjunction:
"the result is either alpha
or beta".
Here we let Q=1
mean "true"and Q=0 mean "false".
Then although in
superposed state |psi> the
result in fact is neither alpha
nor beta,
it turns out to be "true" (Q=1)
that the
result is either alpha
or beta!
(Funny "logic" indeed.)