From: *Bruno Marchal* <[email protected] <mailto:[email protected]>>
On 22 Apr 2018, at 01:47, Bruce Kellett <[email protected]
<mailto:[email protected]>> wrote:
From: *smitra* <[email protected] <mailto:[email protected]>>
On 22-04-2018 00:18, Brent Meeker wrote:
On 4/21/2018 12:42 PM, smitra wrote:
That's then an artifact of invoking an effective collapse of
the wavefunction due to introducing the observer. The
correlated two particle state is either put in by hand or
one has shown how it was created. In the former case one is
introducing non-local effects in an ad-hoc way in a theory
that only has local interactions, so there is then nothing
to explain in that case. In the latter case, the entangled
state itself results from the local dynamics, one can put
ALice and Bob at far away locations there and wait until the
two particles arrive at their locations. The way the state
vectors of the entire system that now also includes the
state vectors of Alice and Bob themselves evolve, has no
nontrivial non-local effects in them at all.
Sure it does. The state vector itself is a function of spacelike
separate events, which cause it to evolve into orthogonal
components...whose statistics violated Bell's inequality.
Brent
There is no non-locality implied here unless you assume that the
dynamics as predicted by QM is the result of a local hidden
variables theory.
Saibal
There is no need to suggest local (or non-local) hidden variables.
The non-locality we are talking about is implied by the quantum state
itself -- nothing to do with the dynamics.
But that type of non-locality has never been questioned, neither in
the MWI, or a fortiori in QM+collapse. But the MWI explains without
the need of “mysterious” influence-at-a-distance, which would be the
case in the mono-universe theory, or in Bohm-De Broglie pilot wave
theory. Without dynamic we have “only” d’Espagnat type of inseparability.
Bruno
It seems that you are starting to see it from my perspective.
Non-locality is just another way of emphasizing the non-separablity of
the quantum singlet state. As you say, this is true in MWI as in
collapse theories. In my extended development of the mathematics in
another recent post, I demonstrated that there is actually no difference
between MWI and CI in this regard. All that we have is the
non-separability of the state, which means that a measurement on one
particle affects the result of measurements on the other -- they are
inseparable. This is all that non-locality means, and this is not
changed by MWI. An awful lot of nonsense has been talked about this --
people trying to find a "mechanism" for the inseparability -- but that
is not necessary. Quantum theory requires it, and it has been totally
vindicated by experiment. That is the way things are, in one world or many.
Bruce
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