[ExI] Many Worlds (was: A Simulation Argument)

Lee Corbin lcorbin at rawbw.com
Tue Jan 15 06:46:47 UTC 2008


John Clark wrote

> Sent: Sunday, January 13, 2008 9:58 AM


> "Lee Corbin" <lcorbin at rawbw.com>
> 
>> If you send a photon through a filter at 45 degrees and someone
>> far away sends the corresponding entangled photon through a
>> similar filter,
> 
> Then there is a 100% probability the photon will make it through that
> second filter ten billion light years away because it is set at the same
> 45 degree angle and the experiment is over.

That's right, (we are considering entangled photons, created at the
same instant but going in opposite directions). Their state is the
single state vector

        |alpha>|rho> + |beta>|sigma>

so that on encountering the "first" polarizer some distance away
the wave function "collapses" so that the "second" polarizer in
the other direction gets 100% of the time the same answer
(pass or absorb). 

The scare quotes are necessary since there really is no "first"
or "second" --- it depends on one's frame of reference. And
there isn't any "collapse" either, at least not to those of us who
accept MWI.  But temporarily believing in faster-than-light
illogical communication at least gives a physicist the right
predictions, even if he needs to abandon that kind of speak
to become coherant.

My modest goal was only to describe why the universe branches
into two pieces, not four.  (Well--okay--there are two other tiny,
tiny, totally non-significant branches of measure almost zero. But
then there are branches where each photon turns into the Taj Mahal,
also of vanishingly small measure.) 

> I don't understand your thought experiment, let me try one of my own.

John now launches into the big  locality-denying  inequality-violating
super Bell type extravaganza/experiment: 

> Some physical processes produce 2 photons that have the same
> polarization but move in opposite directions. A billion years before I
> was born somebody in the Virgo Cluster started making pairs of
> photons that have identical but unknown polarization.

Unknown to whom?  Or do you mean an actual superposition of
all orientations?

> He sent one
> stream of photons to the earth, a billion light years away and he sent
> the second stream of photons to the Coma cluster in the opposite
> direction from the earth also a billion light years away.
> 
> A billion years later on Earth I spin my polarizer to a random direction
> and record its position, I observe if the photon made it through the
> polarizer or not and record that too, the exact time also. Now I spin
> the polarizer again and do the same thing for the next photon and then
> for the next several thousand photons. When his stream of photons
> reach my friend in the Coma Cluster he does the same thing with his photons.
> 
> Now I decide to visit my friend. I get in a space ship with my records
> and blast off for the Coma Cluster at 99% of the speed of light.
> After 2 billion years I arrive in the Coma Cluster, we must be in the
> same universe because I can shake his hand.

Yes, you have to be careful. We remember what happened to Dr. Anti-Teller.

> I now compare notes with my friend. I notice that the direction I had
> my polarizer turned to and the direction my friend had his turned to
> were different, not very surprising since both were picked at random,
> but then I find something astounding. The square of the cosign of the angle 

Least the reader become perplexed, "cosign" is the Coma Berenices
equivalent of our more familiar trigonometric cosine function here on Earth.

> between the 2 detectors for each photon pair is proportional to
> the probability that a photon will make it through my friend's detector.
> That is weird and I see no reason to put the word in quotation marks;
> I know of no theory that can remove that weirdness.

Well, I've read several account of this Bell inequality violating stuff;
yours may be quite good, but I'd have to think about it for a while.

Lee




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