On 7/6/2018 11:44 AM, agrayson2...@gmail.com wrote:
On Thursday, July 5, 2018 at 5:14:34 PM UTC-6, Brent wrote:
On 7/5/2018 3:55 PM, agrays...@gmail.com <javascript:> wrote:
On Thursday, July 5, 2018 at 2:03:46 PM UTC-6, Brent wrote:
On 7/5/2018 11:27 AM, agrays...@gmail.com wrote:
On Wednesday, July 4, 2018 at 10:57:06 AM UTC-6, Brent wrote:
On 7/4/2018 1:57 AM, 'scerir' via Everything List wrote:
*No. I am asserting that the INTERPRETATION of the
superposition of states is wrong. Although I have
asked several times, no one here seems able to offer a
plausible justification for interpreting that a system
in a superposition of states, is physically in all
states of the superposition SIMULTANEOUSLY before the
system is measured. If we go back to those little
pointing things, you will see there exists an infinite
uncountable set of basis vectors for any vector in
that linear vector space. For quantum systems, there
is no unique basis, and in many cases also infinitely
many bases, So IMO, the interpretation is not
justified. AG*
***SIMULTANEOUSLY*** was used by EPR in their paper,
but that did not have much meaning (operationally,
physically).
Can we say that the observable, in a superposition
state, has a ***DEFINITE*** value between two measurements?
No - in general - we cannot say that.
It's in some definite state. But it may be a state for
which we have no measurement operator or don't intend to
measure; so we say it is in a superposition, meaning a
superposition of the eigenstates we're going to
measure. So it does not have one of the eigenvalues of
our measurement.
Brent
*
*
*So for the radioactive source, the superposed state,
Decayed + Undecayed, does NOT imply the system is in both
states simultaneously? *
No, it is in a state that consists of Decayed+Undecayed. So
in a sense it is in both simulatnaeously. If you are sailing
a heading of 45deg you are on a definite heading. But you
are simultaneously traveling North and East. And if someone
was watching you with a radar that could only output "moving
north" or "moving east" it would oscillate between the two
and you might call that a superposition of north and east motion.
Brent
*I see. But as I have pointed out, there are uncountably many
sets of basis vectors that result in the same vector along the 45
deg direction. Thus, it makes no sense to single out a particular
basis and claim it is _simultaneously_ in both. *
That's where you're wrong. It makes perfect sense if that's the
only basis you can measure in. That's why I gave the hypothetical
example of a radar that could only report motion as northward or
eastward. In some cases, like decayed our not-decayed, we don't
have instruments to measure the superposition state. In other
cases like sliver atom spin we can measure up/down or left/right
or along any other axis.
*ISTM, this is the cause of many of the apparent paradoxes in QM
such as Schroedinger's cat, or a radioactive source which is
decayed and undecayed simultaneously. I have no objection using
such a state to do a calculation, but I think it's an error to
further interpret a superposition in terms of simultaneity of
component states. What say you? AG*
I say use what's convenient for calculation. Don't imagine your
calculation is the reality.
*But the consensus, perhaps unstated or subliminally, is that the
superposition is imagined as reality, which leads to cats and
radioactive sources being (respectively) alive and dead, and decayed
and undecayed, simultaneously. Isn't this what Schroedinger was
arguing against? I have rarely, if ever, seen it argued NOT to
interpret a superposition as reality as a proposed solution to these
apparent paradoxes. AG
*
You just go around and around. You never put together the explanations
you get. Decoherence shows that, in the presence of an environment, the
wave function FAPP collapses into orthogonal quasi-classical states in
fractions of a nano-second. That's why the Schroedinger cat story
doesn't show what Schroedinger thought it did. BUT there are
experiments, like silver atoms thru and SG in which superpositions of
left+right persist, they are up polarizations for example; and we know
they exist because we can prepare up states and then measure them
left/right or measure them up/down. The latter, up/down measurement,
would always yield "up" showing they were in an up eigenstate, even
though they were also in a left+right superposition. But there are
other cases where we can't measure the eigenstate (e.g. neutrino family)
so we always describe them as being in a superposition because the
eigenstate is operationally unmeasurable and we can't prepare them in an
eigenstate.
Brent
Brent
*Same for cat, Alive + Dead? Same for ( (Undecayed, Alive)
+ (Decayed, Dead) ) for Schroedinger's composite system? If
that's the case, why would anyone think these states are in
any way paradoxical or contradictory? AG*
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