--- In [EMAIL PROTECTED], "Marvin Long, Jr." <[EMAIL PROTECTED]> wrote:
>
>
>The doctrine of "local realism" rests, as Gribbin describes it, on the
>following assumptions. "First, that there are real things that exist
>regardless of whether we observe them [basic realism];
Well, I think that realism is stronger than this. The nomenon is something
that really exists regardless of whether we observe it. In realism, the
universe exists regardless of whether we observe it.
>second, that it is legitimate to draw general conclusions from consistent
observations or
>experiments [the laws of science and math hold true];
Realism is stronger than this too. With realism, it is legitimate to draw
general conclusions about those things that exist apart from us. Without
realism, the laws of science and math can hold true, but only hold true
concerning what we have observed, what we do observe, and what we will
observe.
>and third, that no
> influence can propogate faster than the speed of light, which
> [D'Espagnat] calls 'locality.'" In this context I interpret "locality"
> as the doctrine that everything exists in its own location in space-time;
> two things can't be in the same place at once, so the fastest an influence
> can get from object A to object B is at the speed of light per special
> relativity. Gribbin doesn't explicitly define the term, so I'm guessing a
> little.
>
Well, you added stuff to locality. Strictly speaking, locality can be
defined as "there can exist no spacelike signals". If two events are
spacelike, there will always be a reference frame in which they are
simultaneous, one in which A is before B, and one in which B is before A.
> What the research regarding Bell's Inequality Theorem shows, however, is
> that local realism and and QM don't mix. I'm not sure how to demonstrate
> this without trying to rehash your original post, Dan, so I won't. In
>short: when a particle splits and creates two particles A and B,
Strictly speaking, it's when two particles are in a superposition. This
does not have to be the result of a decay.
> those particles remain parts of a system "AB," and when particle
> A interacts with something, particle B responds *simultaneously* in
> order to conserve spin, angular momentum, etc., no matter how far
>apart those particles are.
It would be better to remember that, when they are spacelike, there is a
frame in which the observe sees A measured and then B responding and a frame
in which the observer sees B measured and then A responding. The answers
for each are exactly the same, so the measurement order is reference frame
independent. That's critical for relativity.
>However, for a given property a
> particle is always in a state of uncertainty--it has a spin along a
>given axis of +1 and -1 simultaneously,
Closet realism is creeping in here. The particle is in a superposition of
the two states; it does not have two spins simultaneously.
>and there is always some randomness about which way the cookie will
crumble at the moment of
> observation, so normal set theory and statistics don't predict accurately
> the correlations between spin combinations among the various axes of the
> particles. The funky rules of QM, however, do accurately predict what we
> observe.
>
That's a bit off, but the quibbles are small. I'd just like to note that
you are using language that assumes classical realism.
> The fact that A and B respond to each other instantly regardless of
>distance undermines the assumption of locality.
Its only simultaneous in one reference frame. Locality is preserved because
the operators (which represent the measurements) commute. It doesn't matter
which one is done first.
>The fact that observed
> correlations of particle spins don't match the predictions of "normal"
> mathematics, which assume that an object's properties are either fixed or
> will be changed according to fixed and predictable rules, undermines the
> assumption that objects exist, with their attendant properties and
> characteristics, independently of observation or interaction.
>
That part sounds fine.
Dan'm Traeki Ring of Crystallized Knowledge.
Known for calculating, but not known for shutting up
