Entanglement
I believe Brian Greene has a logic error in his discussion of entanglement. He is
attempting to show the spin on photons is pure 50% chance of clockwise or
counterclockwise in each of three axes that he picks. 50% chance is what
quantum theory predicts. But he is trying to disprove other physicists that say
this spin is still 50% but it is programmed at the time the photons are initially
connected. When a calcium atom is excited it can release two photons in
opposite directions. These are entangled, which means they have identical spins.
Actually, they have exactly opposite spins. But this entanglement stands until the
spin is measured even if the photons are light years apart – assuming they had no
other interactions that changes them. Brian is saying they don’t have entangled
spin until the spin is measured.
Now his argument against the programming of the photon spin goes like this.
Choosing three axes to measure the spin of both photons he gives 9 possibilities
for comparing the spins. If we number the axes 1, 2 and 3 with the first number
the first photon and the second the other photon – 1,1 1,2 1,3 2,1 2,2 2,3 3,1 3,2
and 3,3. There are indeed 9 combinations. Say both photons are programmed on
the 3 axes for spin L, L, R (easier to type L or R instead of clockwise or
counterclockwise). Now he says there are 9 ways of matching. (L,L:L,L:L,R:L,L:L,L:
L,R:R,L:R,L:R,R) And if it is programmed 5 of them would match L, L or R,R. So if
they are programmed they would have a greater than 50% chance of being a
match.
My problem with this is there are not nine possibilities. There are only 8. 2
choices for each axis. 2 x 2 x 2 = 8. So the programmed scenario is exactly the
same as the quantum predicted values of 50%. The extra 5th possibility is with 1,2
and 2,1. You can’t count them as 2 occurrences because they are the same L, L, R.
And whether you agree with my “spin” on this or not. Brian’s logic would also
require the quantum 50% probability to have the same 9 combinations with 5
matches which is still greater than 50%. So if he disproved programmed values he
also disproved his quantum values of 50%.