On 9/9/2015 7:10 AM, Stathis Papaioannou wrote:
On Wednesday, September 9, 2015, Brent Meeker <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 9/8/2015 8:20 PM, Stathis Papaioannou wrote:
On 9 September 2015 at 12:44, Bruce Kellett
<bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>> wrote:
On 9/09/2015 12:26 pm, Stathis Papaioannou wrote:
On 9 September 2015 at 10:43, Bruce Kellett
<bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>>
wrote:
On 9/09/2015 9:30 am, Stathis Papaioannou wrote:
On 9 September 2015 at 09:23, Bruce Kellett
<bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>>
wrote:
On 9/09/2015 8:56 am, Stathis Papaioannou wrote:
On 8 September 2015 at 22:11, Bruce Kellett
<bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>>
wrote:
On 8/09/2015 9:14 pm, Stathis Papaioannou wrote:
On 8 September 2015 at 20:48, Bruce Kellett
<bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>>
wrote:
On 8/09/2015 8:40 pm, Stathis Papaioannou
wrote:
On 8 September 2015 at 17:39, Bruce
Kellett <bhkell...@optusnet.com.au
<javascript:_e(%7B%7D,'cvml','bhkell...@optusnet.com.au');>>
wrote:
On 8/09/2015 4:56 pm, Stathis
Papaioannou wrote:
I will ask you the same question as
I did Brent: do you conclude from
the fact that when you toss a coin
it comes up either as head or tails
that the world does not split into
two parallel versions of you, one
of which sees heads and the other
tails?
I would conclude that a coin toss
does not provide any evidence for
multiple worlds or a split. The only
evidence we have from this data is
that the outcome of the toss is
uncertain. There is no evidence
there for any split of anything.
It is not evidence FOR a split but is it
evidence AGAINST a split?
It is evidence that the assumption of a
split is not necessary in order to
understand everyday happenings. So, by
the application of Occam's Razor, no
split happens.
So you agree that we would still observe the
probabilities we do if we lived in a
deterministic world in whaich all
possibilities are realised?
No, because not all possibilities happen in
this world. If all possibilities were realized
in this world, then there would be no
uncertainty, no probabilities. Possibility and
actuality would be the same thing. All the
horses would win the Melbourne cup; and we
don't live in such a world.
Obviously, not all possibilities happen in this
world, but they might happen in parallel worlds
that don't interact with each other. The argument
is that probabilities emerge from this, since you
don't know which world you will find yourself in.
You bet on the favourite in the race because you
think you are more likely to end up in a world in
which the favourite wins.
In other words, probabilities can make perfect
sense in a single deterministic world. This was
understood a long time ago with the development of
statistical mechanics. The idea that "all
possibilities happen in parallel worlds" does not
actually make a lot of sense. There is no current
physical theory that implies this (without the
addition of a lot of unevidenced assumptions). So
probabilities do not emerge from this, they come
from quite simple assumptions of randomness and
ignorance.
Probability in the MWI of quantum mechanics is
problematic. Regardless of claims to be able to
derive the Born Rule in Everettian models, all
attempts fail because they are circular -- they
need the Born rule in order to have non-interacting
worlds, so you cannot then use these independent
worlds to derive the Born rule. Gleason's theorem
is no help -- it suffers from all the same problems
as the Deutsch-Wallace approach.
You don't seem to be disputing that we would still
experience a probabilistic world even if all
possibilities were actually realised, even though you
do dispute that we in fact live in such a world.
I'm not sure if you are disputing that, to give a
simple model case, if a coin was tossed and the world
split in two, with one version of you seeing heads and
the other tails, the probability of each outcome is 1/2.
Whether or not all possibilities are realized, they are
not in evidence, so their relevance to the question of
probabilities is questionable.
Your simple model case of a coin toss causing a world
split is just a made-up example to give the result you
want, so again its relevance is dubious. There is no
sensible physical theory in which the world splits on
classical coin tosses.
If you can't imagine a world split, consider a virtual
reality in which the program forks every time a coin is
tossed, one fork seeing heads and the other tails. You are
an observer in this world and you have this information, so
you know for certain that "all possibilities are realised"
when the coin is tossed. What would you say about your
expectation of seeing heads?
I presume you mean that the world is duplicated on each toss,
with one branch showing each outcome. We are back to the
dreaded "person duplication" problem. My opinion on this is
that on such a duplication, two new persons are created, so
the probability that the original person will see either
heads or tails is precisely zero, because that person no
longer exists after the duplication.
After the coin has been tossed a few times, you (or one of the
entities identifying as you) will say that, despite the opinion
he expressed on 9th September on the Everything List, it does
seem that he has survived the duplication and that heads comes up
about half the time.
But he would say the same thing if only one fork of the program
were executed at each branch. So whether the other branches are
executed is not related to observations.
You can make a similar comment about any observation: we would draw
the same conclusions about the past if the world was created a minute
ago with evidence of a false history.
Exactly so. Do you entertain that as theory? If not, why not?
Brent
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