On 7/10/2018 6:50 PM, [email protected] wrote:
On Tuesday, July 10, 2018 at 4:42:44 PM UTC-6, Brent wrote:
On 7/10/2018 3:01 PM, [email protected] <javascript:> wrote:
*IIRC, the above quote is also in the Wiki article. It's not a
coherent argument; not even an argument but an ASSERTION. Let's
raise the level of discourse. It says we always get a or b, no
intermediate result when the system is in a superposition of
states A and B.. Nothing new here. Key question: why does this
imply the system is in states A and B SIMULTANEOUSLY before the
measurement? AG *
Because, in theory and in some cases in practice, there is a
direct measurement of the superposition state, call it C, such
that you can directly measure C and always get c,
*Is c an eigenvalue of some operator? How can you always get c, if C
is not an eigenstate of some operator? And if it is an eigenstate, why
do you assert it is a superposition? AG
*
You just don't get it. c is the eigenvalue of C. C is an eigenstate.
BUT it's also a superposition of A and B. It's a simple fact of vector
spaces that a vector can be the sum of other vectors. The only thing
tricky about QM is that it's in a complex vector space so the vectors
get scaled by complex instead of real numbers. And they are
/*simulataneously */the sum of other vectors.
Brent
but when you have measured and confirmed the system is in state c
and then you measure A/B you get a or b at random. The easiest
example is SG measurements of sliver atom spin orientation where
spin UP can be measured left/right and get a LEFT or a RIGHT at
random, but it can be measured up/down and you always get UP. Any
particular orientation can be /written/ as a superposition of two
orthogonal states.
*I'm not clear what a left/right measurement is, and how it might be
measured. I assume you mean the directions perpendicular to Up / Dn.
In any event, how is this related to the simultaneity of Up / Dn? AG*
This is true in general. Any state can be written as a
superposition of states in some other basis. But it is not
generally true that we can prepare or directly measure a system in
any given state. So those states we can't directly access, we
tend to think of them as existing only as superpositions of states
we can prepare.
*I'm OK with superpositions, only their_interpretation_ of
simultaneity of component states. We can measure Up or Dn, and
represent the situation before measurement as a superposition and
calculate probabilities, but the assumption of simultaneity seems
unsupported and produces apparent paradoxes. AG *
Brent
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