On 03 Nov 2014, at 02:14, Bruce Kellett wrote:
Bruno Marchal wrote:
On 01 Nov 2014, at 23:55, Bruce Kellett wrote:
Bruno Marchal wrote:
This I find hard to buy. I like the MW notably because it
restores determinacy and locality in the 3p big "physical"
picture. In the MW theory, we can explain the violation of Bells
inequality, without using anything non local, or instantaneous.
I took Aspect experiment as a confirmation of the MW idea.
This is not so obvious. MWI struggles to explain the violations of
Bell's inequality. It can do so only in a very strained way, and
that at the price of counterfactual definiteness. It seems to me
that this price might be too high.
One argument for this is perhaps too simple: the SWE is local and
linear all by itself, so in the Hilbert space of the "universal
wave", there is no "action at a distance". This can be used, I
think, to reduce the question of counterfactual definiteness to the
question of the definiteness of the worlds themselves, and this is
not yet clear to me. Eventually we have to find the MW view of the
Kochen & Specker theorem, well, you may be right that this is not
obvious.
I will try to do this by myself, and get back if I succeed. I am
currently explaining (trying to explain to be sure) to a group of
students how to "reduce" all weirdness of quantum mechanics to only
one: "the parallel universes", but sometimes I do have a problem
with the very notion of "universe", which is rarely well defined,
if define at all. I have always the need to take into account that
we have a brain-base prejudice on the picture of the "whole", and I
think that counterfactual definiteness might be in that category.
Coming from computationalism, with the mind-body problem as
motivation, I am somehow prepared to stop believing in "universe".
Coherent sheaf of dreams, or first person plural sharable
computations, like the one with computationalism, does not have to
converge on well defined "universe(s) independent of us", so I am
not sure if the abandon of counterfactual definiteness would be a
so high price to me. Eventually it might even be welcome, as
computationalism might also forbid it, so ... well, I don't know.
If I succeed in explaining (to me and my students) Bell's
inequality in a purely local way (with many worlds, or better many
relative states (capable of perhaps NOT defining worlds, but only
coherent sharable experience), I will try to sum up the idea here.
Have you read Deutsch and Hayden paper on this? I know that is well
debated, but I have not yet found the time to read/understand the
critics.
I had not read this paper, but I do not find the proposal
convincing. Deutsch seems merely to point to the fact that one
observes the correlation in a Bell-type experiment only after the
classical transfer of information, just as in any other quantum-
teleportation situation. This might be true, but it is not really an
explanation of the correlations.
It seems to me that quantum mechanics explain well the correlations,
which are consequences of the linearity of the tensor product and of
the evolution. Bell, even EPR, assumed implicitly the uniqueness of
the outcome after a measurement.
In fact I challenge the people who believe in non locality to show me
an example, with a proof that there is non-locality, and this without
adding a collapse. I don't see how that could even be possible.
Nor can I make sense of "non-locality" without destroying either
special relativity, or so much of physical realism that even a non
believer in "primary matter" like me get uneasy feelings.
Bruno
Bruce
Bruno
--
You received this message because you are subscribed to the Google
Groups "Everything List" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
http://iridia.ulb.ac.be/~marchal/
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
