On 4/20/2016 10:34 PM, smitra wrote:
On 20-04-2016 07:49, Brent Meeker wrote:
On 4/19/2016 10:21 PM, smitra wrote:
On 20-04-2016 03:02, Bruce Kellett wrote:
On 20/04/2016 6:56 am, smitra wrote:
The mistake made is to invoke classical reasoning after the
measurements are made. If the choice for the orientation of the
polarizers were not made in advance, then Alice and Bob cannot
have said to have made any definite choices at all.
I think you need to learn something about decoherence , and the
emergence of the 'classical' from the 'quantum'. In the final
analysis, Alice and Bob meet to compare their results. By that stage,
their results, and their relative magnet orientations, are definite
and classical (FAPP if you wish). And that is the end result we have
to explain. All else is boondoggle.
Invoking FAPP is precisely where your argument goes wrong. While due
to decoherence the macroscopic world looks classical, in reality
(assuming MWI) it not classical. This means that when Bob meets
with Alice that the settings Alice chose are still not determined.
It is only when Alice communicates to Bob what her polarizer
settings were that Bob becomes localized in that particular sector
of the multiverse where this is now fixed.
What if Bob misunderstands what Alice said - does he get localized in
a different universe. Does he switch back when Alice shows him her
notebook? What if Alice and Bob don't talk directly but instead each
whispers in Bruce's ear, but they speak urdu so Bruce doesn't know
what they said until he consults a translator?
As you write below and as I've just replied to Bruce, what matters is
that this information does not spread faster than the speed of light.
But in principle, the sector of the multiverse where is is located has
a width measured in branches of the environment, that is inversely
proportional the the amount of reliable information he has about his
local information. So, if he has a lot of hair on his head and has
never counted the exact number then he is in many different branches
where this number is different.
That seems to be variety of QBism in which case we can stop attributing
existence to the wave function - it's just a summary of Alice's (or
Bob's) knowledge and it "collapses" when she gains new knowledge.
Brent
The person I was when I was 3 years old is dead. He died because
too much new information was added to his brain.
-- Saibal Mitra
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