Which universe are we in? (tossing tennis balls into spinning props)

[drs]

On n Tuesday, July 16, 2002, at 11:02 Tim May wrote:
 >On Tuesday, July 16, 2002, at 10:39  AM, Peter Fairbrother wrote: 
 >> Oh dear. QM does rule out internal states. I didn't think I would
 >> have to explain why I capitalised "Bell", but perhaps it was a bit
 >> too subtle. Google "Bell" and "inequalities", and go from there.
 
 > I disagree. Bell's Inequality is not dependent on QM...it's a 
 > mathematical statement about the outcomes of measurements where 
 > stochastic processes play a role. The fact that QM is strongly
 > believed to involve stochastic processes is why Bell's inequality
 > shows up  prominently in QM. However, we cannot then use B.I. to
 > prove things about QM.
 
  It's a statement about quantum mechanics. Quantum mechanics and the 
violation of bell's inequality rest on the inseparability of a quantum
state. Typically, that means a test using an epr pair, i.e. a pair of
S = 1 photons with total J = 0, so that the pair behaves as a single
object with J = 0. The pair MUST be originate from the same quantum
process, (e.g., a single \pi_{0} decay), not as two arbitrarily selected
photons from a stochastic process (e.g., 2 photons selected at random
from the 4 produced in the decay of two pions). In short, quantum mechanics
is not stat mech.

 > A more persuasive proof of why hidden variables are not viable in QM is 
 >the work done on extending some theorems about Hilbert spaces. Namely, 
 >Gleason's theorem from the mid-50s, later extended by Kochen and Specker 
 >in the 1960s. The Kochen-Specker Theorem is accepted as the "no go" 
 >proof that hidden variables is not viable.

  While K-S is an improvement, it's fundamentally the same idea as bell's
but eliminates a loop-hole:

  From: http://plato.stanford.edu/entries/kochen-specker/

   "This is the easiest argument against the possibility of an HV 
   interpretation afforded by Gleason's theorem. Bell (1966: 6-8) offers a
   variant with a particular twist which later is repeated as the crucial
   step in the KS theorem. (This explains why some authors (like Mermin
   1990b) call the KS theorem the Bell-Kochen-Specker theorem; they think
   that the decisive idea of the KS theorem is due to Bell.[3]) He proves
   that the mapping  dictates that two vectors and  mapped into 1 and 0
   cannot be arbitrarily close, but must have a minimal angular separation,
   while the HV mapping, on the other hand, requires that they must be
   arbitrarily close."

 In any case, quantum mechanics is well established by a lot of convincing
arguments, even without any of the above to rely upon.