[ExI] Free will was: Everett worlds

[John Clark]

On Tue, Aug 18, 2020 at 8:49 AM Stuart LaForge via extropy-chat <
extropy-chat at lists.extropy.org> wrote:


> * > When either you or I measure the spins of an entangled pair
> of electrons from light years apart, we collapse the wave function by doing
> so but SOMETHING decides whether we observe the spins as up-down or down-up*


If Many Worlds is right then NOTHING decides if John Clark observes spin up
or spin down because John Clark observes both, the particle John Clark is
observing splits and so does John Clark. By the way, although it sounds
awkward in thought experiments involving Many Worlds I often use proper
nouns because personal pronouns tend to get you into trouble. In Many
Worlds everything that can happen, that is to say everything the
Schrodinger wave equation allows, does happen, and the English language was
not really designed for that kind of discussion, so It will need a major
overhaul of the way it uses pronouns once technology to make copies of
individuals accurate to within a nanometer becomes common.

> *You can call it random chance, but that doesn't explain the
> instantaneous correlation between our measurements from light years apart.*


Schrodinger's wave equation is purely deterministic and so the Multiverse
must be too. If a particle that is in a spin zero state decays and I
observed that one of the decay particles is spin up then I must be in a
universe where it's brother particle is spin down and it makes no
difference if the particle is a billion light years away because the
Schrodinger wave equation forbids anything else.


> *> you are left with the mystery of unitarity. That is to say, how do
> different universes containing the same particle in different quantum
> states always know how to be different from their sister universes if the
> universes cannot communicate with one another?*


The particles are correlated but they are not in communication with one
another, you can't use quantum entanglement to send messages faster than
light.


> >
> *Who or  what is keeping track of the probabilities such that they always
> sum to one? In MWI, unitarity begs the question of non-locality.*


You're basically asking where the Born Rule came from, why is the
probability of finding a particle at point X equal to the square of the
absolute value of Schrodinger's wave at that point? Gleason proved in 1957
that if Schrodinger's wave is related to probability then the square of the
absolute value is the only one that doesn't produce contradictions. So if
you're going to have a probability rule involving a wave function it has
got to be the Born Rule, the function cubed or anything else just won't do.
But if Schrodinger's Equation and thus the entire Multiverse is 100%
deterministic why involve probability at all? Because each individual version
of me can only see a very small slice of the multiverse, until I actually
observe the particle in question I am lacking vital information, I have no
way of knowing if I am in the universe that has the spin up particle or the
one that has spin down. Probability is necessary for predicting the
behavior of something even if it's completely deterministic if you have
incomplete information about it.

John K Clark
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