On 17 Nov 2017, at 23:18, Bruce Kellett wrote:
On 18/11/2017 12:10 am, Bruno Marchal wrote:
On 15 Nov 2017, at 22:26, Bruce Kellett wrote:
On 16/11/2017 1:55 am, Bruno Marchal wrote:
On 15 Nov 2017, at 00:55, Bruce Kellett wrote:
On 15/11/2017 12:47 am, Stathis Papaioannou wrote:
On Mon, 13 Nov 2017 at 8:54 am, Bruce Kellett <[email protected]
> wrote:
I don't think you have fully understood the scenario I have
outlined.
There is no collapse, many worlds is assumed throughout. Alice
splits
according to her measurement result. Both copies of Alice go to
meet
Bob, carrying the other particle of the original pair. Since
they both
have now met Bob, the split that Alice occasioned has now
spread to
entangle Bob as well as the rest of her environment. So there
are now
two worlds, each of which has a copy of Bob, and an Alice, who
has a
particular result. Locality says that Bob's particle is
unchanged from
production, so when he measure its spin, he splits into two
copies,
according to spin up or spin down. Since Alice is standing
beside him,
she also becomes entangled with his result. But Alice already
has a
definite result in each branch, so we now have four branches:
with
results 'up-up', 'up-down', 'down-up', and 'down-down'.
However, only
the 'up-down' and 'down-up' branches conserve angular momentum.
How do
you rule out the other branches?
When you put something in the cupboard and come back later to
get it, why, under MWI, is it still there?
I don't understand the significance of your question. Why
wouldn't things remain stable in MWI? After all, the whole
world, as it is, becomes entangled with the particular branching
event.
OK, but not instantaneously. This might be the point where we
disagree in the interpretation of the Non-collapse theory.
I think that the general idea is that the entanglement with the
result spreads at the velocity of light -- inside the forward
light cone. This spread of entanglement does not require that all
objects in the forward light cone have explicitly interacted with
the original event. The mathematics are quite clear on this point.
You are right. So you might need an experience like Mandel & Co(I
will look at the reference, I guess you see which experience I
allude to) where two distant lasers create a singlet state non
locally. That one has made me doubt that MW could avoid Action-at-a-
distance, and some thought experience by Lucien Hardy too, but
eventually, I remain unconvinced,
You will have to give more precise references. Searching on these
names throws up so many papers that it is impossible to sort out
exactly what you mean here.
I think it should be this one:
Z.Y. Ou, L. Mandel, Violation of Bell’s inequality and classical
probability in
a two-photon correlation experiment, Phys. Rev. Lett. 61, 50–53 (1988)
because wherever are the actors, the singlet state never describes
a non-local affair, it only predicts the result of the people who
will met at some time.
The singlet state is intrinsically non-local.
I am not sure what that means, but I can imagine this could make sense
in the "one-world" hypothesis, not much in many-worlds, still less in
many-computations.
A simple argument is that any experimental set-up showing a non-
locality can be simulated by a classical (local) computer, and the
simulated observer(s), like all the Bob-Alice pair we get, will all
(the majority) describe an apparent non-locality, despite we, looking
patiently at the whole emulation will see that there are none.
It actually has nothing to do with whether people meet or not - it
describes a situation which explicitly violates Einstein's notion of
local realism: the state of one of the entangled pair is not
separable from the state of the other distant particle. Non-
separability here implies non-local influence, or simple non-
locality. The attempt to claim that non-separability does not imply
non-locality is mere verbal gymnastics, with no physical content.
The singlet state does not describe one pair, but an infinity of
pairs, having spin (say) in all directions, but correlated in all the
case verifiable by Bob and Alice when they can interact. I would say.
Bruno
Bruce
--
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 https://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 https://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
