On 2/22/2020 7:11 PM, Bruce Kellett wrote:
On Sun, Feb 23, 2020 at 10:56 AM 'Brent Meeker' via Everything List
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On 2/22/2020 2:39 PM, Bruce Kellett wrote:
On Sun, Feb 23, 2020 at 9:23 AM 'Brent Meeker' via Everything
List <[email protected]
<mailto:[email protected]>> wrote:
On 2/22/2020 2:10 PM, Bruce Kellett wrote:
On Sun, Feb 23, 2020 at 7:17 AM 'Brent Meeker' via
Everything List <[email protected]
<mailto:[email protected]>> wrote:
But isn't that just a matter of it's proponents
overselling it. If you say, well it's a probabilistic
theory, then that the Born rule is the way to get a
probability is fairly compelling.
Many-world proponents certainly oversell Everett. I have not
seen anybody admit openly that there is a problem with
getting probability into a deterministic theory so it just
has to be put in by hand. If, as you say, people admit that
what they really want is a probabilistic theory, even if
they have to force it in by hand, then at least some of the
arguments for the Born rule make sense. But if you insist
that your theory is pure SWE/Everett, then all attempts at
deriving the Born rule from this deterministic position fail.
The arguments that I have developed here, based on Kent's
insight, take Many-worlds at face value. Then the theory is
clearly incoherent, or at least incompatible with
observation. However, if you take a classical deterministic
theory, such as Bruno's WM-duplication thought experiment,
then there is no way you can sensibly interpret such a
theory probabilistically.
You don't think copying of persons has a probabilistic
implication for copies?
Only if you say so. The trouble, as I have pointed out, is that
if they estimate their probabilities on the basis of the data
they each collect from repeated trials, they all come to
different answers. And all of these answers are equally
justifiable. The concept of "a probability" in this situation is
valueless.
You're still assuming that there is no statistical convergence in
the MWI answers, as is assumed in one world?
I don't really understand your comment. I was thinking of Bruno's
WM-duplication. You could impose the idea that each duplication at
each branch point on every branch is an independent Bernoulli trial
with p = 0.5 on this (success being defined arbitrarily as W or M).
Then, if these probabilities carry over from trial to trial, you end
up with every binary sequence, each with weight 1/2^N. Summing
sequences with the same number of 0s and 1s, you get the Pascal
Triangle distribution that Bruno wants.
The trouble is that such a procedure is entirely arbitrary. The only
probability that one could objectively assign to say, W, on each
Bernoulli trial is one, since W certainly occurs for each trial. In
other words, there is no natural probability associated with this
duplication process, so imposing one is ad hoc and arbitrary.
In MWI, it seems that Carroll gives the conventional answer -- weights
are arbitrarily assigned to branches according to the branch amplitude
(modulus of the coefficient squared). This is arbitrary too, designed
merely to give the same answer that is naturally obtained in the
single world case. What I object to about this is not only its
arbitrariness, but also the fact that it is advertised as a
"derivation" from the SWE, when it is no such thing. It is arbitrarily
imposed.
It's imposed. But it's hardly arbitrary. First, it agrees with
experiment. Second, Gleason's theorem shows it's the only
mathematically consistent measure that could be used as a probability.
And Zurek tries to prove it's implied by symmetry considerations.
Brent
So MWI is cheating. At least in text-book Copenhagen approaches, there
is no secret about the fact that the Born rule is adopted merely to
give agreement with experiment. The data are probibalistic, so the
theory is modified to also be probabilistic. Honesty is a virtue in my
eyes.
Bruce
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