Entangled
Quantum States

John
Bell brilliant theoretical physicist

He didn’t
like quantum mechanics (thought it was rotten)

John
wheeler thought that it was beautiful

Feynman:
Quantum Mechanics deals with amplitudes for initial to final state

What's
the amplitude for us to go from one to the other and specify the final state

Bohr: different experimental arrangements are part
of the specification of the quantum mechanical process

Decoherence- as soon
as you a macroscopic system with quantum mech. System, the state is much more
complicated

EPR
paradox- some system with angular momentum that can decay into an electron and
a positron

Thought
that quantum mechanics was incomplete

If we can
determine a value of a property of that system then that was an element of
reality

If
electron is spin up, then positron is spin down

Sz is real

Sx is real

Spooky
action at a distance, reality

Depends
on what the other experimenter does

Bell
shows that it doesn’t work with inequalities that any hidden variable theory
would have to obey