Re: Nonlocality

Dejan Vucinic (
Tue, 17 Sep 1996 13:55:10 -0500

>From my understanding tof Paulis Exlusion principle and rudimentary
>quantum mechanics, couldnt you use electron spin states for FTL
>communication, if not travel. By spreading two electrons really far
>apart, and changing the state of one, shouldnt the other one shift
>instantly, enabling us to communicate digitally faster than light.

The problem here is "rudimentary." Quantum mechanics is not a theory
of everything. It is just a little better model of small scales than
classical (i.e. Newtonian) mechanics. If you go to high energies
(large velocities, small wavelengths) you need relativistic quantum
mechanics for making predictions. If you have a system with
a large number of particles, you need statistical quantum mechanics.
If you want both, well, then you'd better have a nice cosmology... :)

So, the answer is "no." But it's not "no because quantum mechanics
forbids it." It's "no because experiment shows that the universe
doesn't work like that." And quantum mechanics is not a very good tool
for modeling the particular experiment you're mentioning.
(Are you feeling philosophical yet? A common QM entry-level mistake
is trying to "intuitively" understand quantum mechanics. Beware!)

>Ive stopped lurking.

Good for you, but a question like that belongs to sci.physics or
some such. I'd be surprised if it weren't a FAQ.