[FOM] Quantun mechanics realm

[scerir]

From: "laureano luna" 
> I wonder whether theories including hidden variables 
> are consistent with some empirical and mathematical 
> results that seem to show complementary properties 
> of particles cannot really be definite at the same time 
> and cannot exist independently of our measurements 
> of them. 
> I'm referring to the Kochen-Specker theorem and to 
> the experiments that reveal violations of Bell's 
> inequality.   
> I'm inclined to think those outcomes bannish any 
> possibility of a hidden variables theory. 
> Is it not so?

John Bell writes in 1966 (on Rev.Mod.Phys.) that 
"It was tacitly assumed that measurement of an 
observable must yield the same value independently 
of what other [compatible] measurements may be made 
simultaneously [....] There is no apriori reason 
to believe that the results should be the same. 
The result of an observation may reasonably depend 
not only on the state of the system (including hidden 
variables) but also on the complete disposition of 
the apparatus [...]".

It is easy to realize that the above has much to
do with some famous dictum of N.Bohr, such as "the 
impossibility of any sharp distinction between the
behaviour of atomic objects and the interaction
with the measuring instruments which serve to define
the conditions under which the phenomena appear."
It is easy to realize that Bohr's "complementarity"
principle, if not Heisenberg's "uncertainty" principle
has much to do with Bell's and Kochen-Specker
"contextuality". 

What John Bell (1966) and Kochen-Specker (1967) 
showed is that any *deterministic* theory (and any hidden 
variable cryptodeterministic theory) which would attribute 
a *definite* result to a quantum measurement, still 
*reproducing* the statistical properties of the 
indeterministic QM, must be "contextual".

What John Bell (in another more famous theorem), 
and Ghirardi, and Eberhard, etc. showed, is that
any *deterministic* theory (and any hidden variable 
cryptodeterministic theory) which would attribute 
a *definite* result to a quantum measurement, 
still *reproducing* the statistical properties of 
the indeterministic QM, must be "superluminal",
in case of measurements performed on space-like
separate entangled particles.

So deterministic theories (but reproducing QM results) 
are not ruled out, in principle, but they are extremely 
improbable.

-serafino cerulli-irelli