On 6/20/2019 11:11 PM, Bruce Kellett wrote:
On Fri, Jun 21, 2019 at 3:38 PM 'Brent Meeker' via Everything List
<[email protected]
<mailto:[email protected]>> wrote:
On 6/20/2019 10:00 PM, Bruce Kellett wrote:
On Fri, Jun 21, 2019 at 2:35 PM 'Brent Meeker' via Everything
List <[email protected]
<mailto:[email protected]>> wrote:
On 6/20/2019 9:09 PM, Bruce Kellett wrote:
On Fri, Jun 21, 2019 at 1:19 PM 'Brent Meeker' via
Everything List <[email protected]
<mailto:[email protected]>> wrote:
On 6/20/2019 5:56 PM, Bruce Kellett wrote:
From: *Bruno Marchal* <[email protected]
<mailto:[email protected]>>
I don’t think your refutation of step 3 has been
understood by anyone.
If someone else want to argue that there is no
indeterminacy in the self duplication experience, he
is welcome.
I think that some might challenge your interpretation
of this indeterminacy. This might not be exactly JC's
objection to step 3, but, to my mind, it is a serious
difficulty in its own right.
This comes from a recent podcast of a conversation
between Sean Carroll and David Albert:
https://www.youtube.com/watch?v=AglOFx6eySE
This is a long discussion, and the relevant parts of
Albert's objections to MWI and self-locating
uncertainty come towards the end.
The essence of Albert's point is that in the
duplication case, you ask "What is the probability that
you will find yourself in Moscow (resp. Washington)?"
Putting aside objections to the non-specificity of the
pronoun 'you', I think your answer is that the
probabilities are 0.5 for either city. Albert points
out that to reach this conclusion, you use some
principle of indifference, or point to some symmetry
between the possible outcomes. Using this symmetry, you
claim that the probabilities must be equal, hence 0.5
for each city. Now, says Albert, there is another
solution that also respects all the symmetries
involved, viz., "I have not idea what the probability is."
You can then easily argue that this is a better
solution. Because the probability 0.5 is not written in
the physics of the situation -- it comes entirely from
the classical principle of indifference. So Albert asks
how you are going to verify this probability
experimentally -- as a large N limit, or something
similar. So you repeat the duplication N times on your
participants. i.e. after the original duplication you
transport the subjects back to Helsinki and repeat the
duplication to Washington and Moscow. You end up with
2^N copies, each of which has a record of the N cities
they found themselves in after each duplication. You
now ask each of them their best estimate of the
probabilities for W or M on each duplication. Of
course, you then get all possible answers, from 1/N for
M to 1/N for W. Since, withprobaility one, the will
always be someone who found himself in M each time, and
similarly, someone who found himself in W each time.
Plus all other 2^ possible combinations of results.
But most participants will say they were in Washington
approximately N/2 times and Moscow N/2 times, in
accordance with a binomial distribution.
But I am not "most participants". I am just me, only one of
me. I could easily be the guy who sees 100% Moscow.
Not "easily" since seeing only Moscow has probability
1/2^N. And it's not just you I need to convince. I need to
write a paper showing that my P(M)=P(W)=0.5 theory is
supported and the statistics reported by the participants do
exactly that.
As Bruno might say, that is to take the 3p view of things. I am
concerned about the 1p view, where this survey of all
participants is not possible.
The point, of course, is to relate this to the many worlds
interpretation of QM. There one does not have the option of
surveying outcomes over all branches in order to reach one's
conclusions about probabilities. Put another way, if MWI is true,
why do we not regularly see substantial deviations from the Born
Rule probabilities?
A good question /*if*/ the premise is true. Are you saying that
splitting photons by a half-silvered mirror doesn't produce
binomial statistics, which the variance = Np(1-p)? Are you saying
the measured variance is greater than expected... or less?
After all, repetitions of the relevant interactions are happening
all the time: and not just in our controlled experiments. How can
there be such things as objective probabilities in the MWI
scenario? How can we use experimental evidence to support
theories when we do not know whether our observer probabilities
are representative or not?
The same as in any probabilistic theory. We repeat it so many
times that we have statistics that we can compare to the
theoretical distribution. The same way you would test your theory
that a coin was fair.
In other words, MWI is experimentally disconfirmed.
How so? In repeated experiments I'm aware of (and a lot of photons go
thru Aspect's EPR experiments) the statistics are consistent with the
theory. To disconfirm MWI you'd have to observe statistics far from the
expected value, which is why Tegmark proposed his machine gun suicide
experiment.
Brent
Bruce
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