On 9/09/2015 9:30 am, Stathis Papaioannou wrote:
On 9 September 2015 at 09:23, Bruce Kellett <bhkell...@optusnet.com.au
<mailto: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 <mailto: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
<mailto: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
<mailto: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.
Bruce
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