On 27 Nov 2017, at 18:10, Lawrence Crowell wrote:
On Sunday, November 26, 2017 at 8:29:22 AM UTC-6, Bruno Marchal wrote:
On 24 Nov 2017, at 15:59, Lawrence Crowell wrote:
On Thursday, November 23, 2017 at 5:53:14 PM UTC-6, Bruce wrote:
On 24/11/2017 10:15 am, Lawrence Crowell wrote:
On Wednesday, November 22, 2017 at 9:37:48 AM UTC-6, Bruno Marchal
wrote:
On 20 Nov 2017, at 23:04, Bruce Kellett wrote:
You clearly have not grasped the implications of my argument. The
idea that "MWI replaces all nonsensical weirdness by one fact
(many histories)" does not work, and is not really an explanation
at all -- you are simply evading the issue.
Without collapse, the apparent correlations are explained by the
linear evolution, and the linear tensor products only. I have not
yet seen one proof that some action at a distance are at play in
quantum mechanics, although I agree that would be the case if the
outcome where unique, as EPER/BELL show convincingly.
Aspect experience was a shock for many, because they find action
at a distance astonishing, but are unaware of the many-worlds, or
just want to dismiss it directly as pure science fiction. But
after Aspect, the choice is really between deterministic and local
QM + many worlds, or one world and 3p indeterminacy and non
locality. Like Maudlin said, choose your poison.
Bruno
Bruce
I am new to this list and have not followed all the arguments
here. In weighing in here I might be making an error of not
addressing things properly.
Consider quantum entanglements, say the entanglements of two spin
1/2 particles. In the singlet state |+>|-> + |->|+> we really do
not have the two spin particles. The entanglement state is all
that is identifiable. The degrees of freedom for the two spins are
replaced with those of the entanglement state. It really makes no
sense to talk about the individual spin particles existing. If the
observer makes a measurement that results in a
measurement the entanglement state is "violently" lost, the
entanglement phase is transmitted to the needle states of the
apparatus, and the individual spin degrees of freedom replace the
entanglement.
We have some trouble understanding this, for the decoherence of
the entangled state occurs with that state as a "unit;" it is
blind to any idea there is some "geography" associated with the
individual spins. There in fact really is no such thing as the
individual spins. The loss of the entangled state replaces that
with the two spin states. Since there is no "metric" specifying
where the spins are before the measurement there is no sense to
ideas of any causal action that ties the two resulting spins.
This chaffs our idea of physical causality, but this is because we
are thinking in classical terms. There are two ways of thinking
about our problem with understanding whether quantum mechanics is
ontic or epistemic. It could be that we are a bit like dogs with
respect to the quantum world. I have several dogs and one thing
that is clear is they do not understand spatial relationships
well; they get leashes and chains all tangled up and if they get
wrapped up around a pole they simply can't figure out how to get
out of it. In this sense we human are simply limited in brain
power and will never be able to understand QM in some way that has
a completeness with respect to causality, reality and nonlocality.
There is also a far more radical possibility. It is that a
measurement of a quantum system is ultimately a set of quantum
states that are encoding information about quantum states. This is
the a quantum form of Turing's Universal Turing Machine that
emulates other Turing machines, or a sort of Goedel
self-referential process. If this is the case we may be faced with
the prospect there can't ever be a complete understanding of the
ontic and epistemic nature of quantum mechanics. It is in some
sense not knowable by any axiomatic structure.
Hi Lawrence, and welcome to the 'everything' list. I have come here
to avoid the endless politics on the 'avoid' list.
The issue that we have been discussing with EPR pairs is whether
many worlds avoids the implications of Bell's theorem, so that a
purely local understanding of EPR is available in Everettian
models. I have argued that this is not the case -- that non-
locality is inherent in the entangled singlet state, and many
worlds does not avoid this non-locality. I think from what you say
above that you might well agree with this position.
Bruce
Of course MWI can do nothing of the sort. MWI suffers from much the
same problem all quantum interpretations suffer from.
I don't see this. the MW theory (that is the WWE without the
collapse axiom) explains the violation of inequality in a way which
avoids any action at a distance, but when we assume one universe,
like Einstein explains very clearly already in 1927, you get a
notion of simultaneousness incompatible with special relativity and
very minimal form of realism.
For me, as a logician, I consider that SWE and SWE+collapse are
different theories. The first is local, deterministic and admits a
local physical realism, the second is not intelligible at all, as
the notion of observer is unclear and dualistic.
Bruno
I suppose I don't know what WWE means.
I meant SWE. Typo error. Sorry.
MWI is not a bad idea, but I frankly question whether it along with
all other interpretations are properly scientific theories.
To me: it is the natural interpretation of QM without collapse. You
need adding some axiom to avoid the literal many-histories, and
indeed, that is why the founders added the collapse axiom, which taken
literally just limit the application of the SWE so that it does not
apply to the observer. In logic, we have a name for the notion of
"literal interpretation" of a theory: it is called an Herbrand
Interpretation. The Herbrand interpretation of the SWE has provably
the many "worlds".
I see no particular way that any quantum interpretation can be tested.
Well, if there is a collapse in between consciousness and the
particles, it should be observable.
The idea is nice in that it gives an idea of a total universe as
unitary, but where the phenomenology has us moving along one
particular path in a decoherence event. However, if we are to have a
splitting off of the world we might think of there being a many
block world perspective, where a decoherence of a quantum event
splits off quantum amplitudes on all possible spatial surfaces that
contain this event. This has been referred to in the past as the
gemische; all possible spacelike manifolds that embed a measurement
event. However, we have some ambiguity with respect to probability
amplitudes associated with each path in this splitting.
Such splitting is probably still too much naïve. In "many-worlds" the
interpretation is one what we mean by "world", not on "many". I tend
to not believe in any world: only in histories, and I expected the
"many", because (assuming Digital Mechanism), elementary arithmetic
emulates (in a block-mindscape) all machines (and humans) subjective
experience. We are not in a "matrix", but in infinitely matrix, and
this predicts the indirect evidence of the "many histories" below our
mechanist substitution level (Mechanism is the bet that below some
description level we can survive with a digital brain emulating us
below that level).
Bruno
LC
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