Re: Two EPR questions

From: Thomas Trotter (thomastrotter2005_at_juno.com)
Date: 10/27/04 

Date: Wed, 27 Oct 2004 15:56:11 +0000 (UTC)

[snip]

Patrick Van Esch:
> > However, the interference of results in an EPR like setup are not more
> > surprising than the interference of a split light beam that went
> > around the building left and right and came back.

Ilja Schmelzer:
> No. This type of (classical wave) interference may be explained in
> a classical realistic local theory, violations of Bell's inequality not.

TT:
Not yet anyway. :-) Maybe it's just that knowledge of what is
actually happening wrt the emission and detection of the opposite
moving light beams is incomplete (ie., that there *is* a local,
common-property reason for the correlations, and not enough is
known about the physical process to talk about it in a straighforward
local realistic way yet).

[snip]

Patrick Van Esch:
> > We can only notice the effect when, through normal, sub-luminal
> > signalling, we have access to both measurements. So what is the
> > conspiracy ?

Ilja Schmelzer:
> I don't see much conspiracy. I see that we observe a causal
> connection but are unable to observe its direction. That's the whole
> conspiracy: A typical case of indirect, incomplete observation.
> The normal conclusion is that there is a causal connection
> with some causal direction which is hidden from observation.

TT:
It seems clear to me that we don't observe a causal
connection between A and B (though it might be inferred
via the absence of a non-contradictory local model).
The causal contexts are emitter-->polarizer-->detectorA
and emitter-->polarizer-->detectorB. The correlations
aren't produced in those contexts.

In the correlational context there are two
alternative explanations: either the crossed linear
polarizers are analyzing a common property of
the opposite moving light beams due to their
emission from the same oscillator (and, via Bell's
analysis we don't know enough about the process
to formulate it realistically in a non-contradictory
way), or there is some sort of instantaneous physical
mechanism, A-->B and B-->A.

Since all observational evidence suggests a
local reality, I think it's too early too assume
that instantaneous mechanisms or FTL processes
*exist* in any sense other than as artifacts
of our imagination and/or ignorance.

Relevant Pages
Quantcast