On 05 Nov 2014, at 18:56, Richard Ruquist wrote:
Bruno: The differentiation can't go faster than light
Richard: How is that consistent with the EPR experiments?
Where is the inconsistency? EPR and Bell assumes unicity of the
outcomes. But like the indeterminacy, the non locality is an illusion
due to the fact that people share the entanglement, once they make
measurement.
let 0 = 0' + 1'
and
1 = 0' - 1'
This describes the maximally incompatibe bases for some qubit (spin of
electron, for example, or photon polarization). I assume all this is
multiplied by 1/sqrt(2).
0 can be seen equivalently as an infinity of computations in which the
particle and its "doppleganger" are all in state 0, or mixture of one
half computations where there are in state 0' and in state 0.
By the tensor product x, (paul x 0) can be seen as either Paul in
front of a particle in state 0, in an infinity of computations, or one
halve of paul in front of 0' and one have in front of 1'.
Now the EPR state 00 - 11 is more amazing, 'course, as it is
equivalent to 0'0' - 1'1', and to 0"0" - 1"1" and this for all bases
{0,1}, {0',1'}, {0", 1"}, ...
If Alice and Bob makes measurement on their particles, their projects
themselves in the partition of the possibilities described by the
quantum state. If you can show me something non local occurring in a
branch or in a computation, I would be interested. All what I see are
correlation, which looks non local only because we focus on one
computations instead of looking at the entire wave. It would be long
to make the development, right now, but I intent to let my students
search for something non local.
It might be clearer or simpler with teleportation, where you see in
the finale four Alices obtaining each one among the four times two
bits as result of her measurement of their two qubits (the one
teleported, and the one she share entangled with the one Bob keeps, to
stay in quantum touch with Alice), and you see those four Alice
communicating the two bits by classical means in the four universes
(equivalent class on the infinity of one), on which she was projected
coherently with Bob.
And all this does not depend of the choice of the bases to describes
the whole thing, once you make the decomposition so as to be able to
read the diaries of Alice and Bob (whose brains is supposed to exploit
some particular bases).
I know I am a bit short, but eventually, if someone thinks that there
is something non local, they have to prove that extraordinary
assertion. I can see things looks non local in all diaries, like
somethings can look non deterministic, but not the the big picture,
taking account the relativity of all states involved.
What is weird is the complementarity of the maximally incompatible
bases. One world/computation in one base, is an infinity of different
world/computation in its maximally incompatible base. That is weird,
but we are used to that weirdness with position and momentum, and the
Fourier transform. Why is that so? Open problem in machine's theology.
It should comes from the orthogonal structure on the probabilities
imposed by the intensional variant of self-reference.
Bruno
On Wed, Nov 5, 2014 at 12:26 PM, Bruno Marchal <[email protected]>
wrote:
On 04 Nov 2014, at 22:47, meekerdb wrote:
On 11/4/2014 9:23 AM, Bruno Marchal wrote:
On 02 Nov 2014, at 19:09, meekerdb wrote:
On 11/2/2014 1:27 AM, Bruno Marchal wrote:
On 01 Nov 2014, at 23:52, meekerdb wrote:
Are you aware of the Paul-Pavicic "bomb" detector?
http://cds.cern.ch/record/395858/files/9908023.pdf
I did not know this. Impressive.
It is most easily thought of as non-local in time.
I will have to think about that. If you can elaborate. I think I
intuit what you are saying, but well, I need to work more on this.
Intuitively a photon is encouraged to enter the detector because
it is in resonance with an earlier instance of itself that is
already circulating in the detector. The experiment has not
actually been done; but I think it would not work if you
determined the time of emission of the photon to a precision on
the order of the circulation time in the detector.
Is this based on some (relativistic?) account of the energy-time
"uncertainty relation"?
I must confess I have some difficulty to grasp your explanation
but that might be due to my incompetence.
More likely a misfire of my intuition. I base it on their analysis
which just takes classical analysis of a continuous EM wave of a
single frequency (they note that a CW laser can have a 300Km
coherence length so this is a good approximation). So the solution
is an EM field which is constant in time, modulo the traveling
phase. Then they interpret this as a probability amplitude for a
single photon. This implicitly makes the probability amplitude for
that single photon dependent on the wave that is assumed to be time
invariant. But then if you push the quantum viewpoint further,
that classical wave is just a probability amplitude for photons
that came earlier.
OK.
Of course like most quantum weirdness the weirdness comes from
assigning an interpretation that explicitly splits the wave and
particle pictures.
Is that not exactly what does the Copenhague dualisme, or von
Neumann projection? Hmmm ... ?
http://arxiv.org/pdf/1112.4522.pdf
No problem with that paper. As I am a bit skeptical about non-
locality, I am, like the author, certainly annoyed by the language
making people believing that there is some retro-causality involved
in delayed choice experiment.
Now I will try, perhaps with my students, to get some "clearer" many-
world pictures of such non-locality in time.
Note that the usual Bell type of spatial non-locality is a non-
locality in time for any observer in motion with respect to Bob and
Alice. In the relativist frame, non-locality is always space-time
non-locality.
I just saw that Weinberg (in his "lectures on QM") seems to believe
that the MWI is automatically non-local, but I guess he points on
the MW theories which assumes some instantaneous split of the entire
universe. This of course makes no sense. The splitting, or
differentiation, goes at the interaction speeds. Superposition are
contagious, but not so much as becoming instantaneous. The
differentiation can't go faster than light.
I saw also that he attributes to Nicolas Gisin a theorem showing
that if we make the SWE slightly non linear, we get the possibility
of non local interaction between separated observers, that is,
instantaneous action at distance. He does not refer to its own
similar result. That Weinberg's book is very nice, if a bit short on
Bell, QC and foundations, (but then it is nice it refers to that
matter, don't avoid Everett, nor Bell, and there are other good
books on that topics (like Hirvensalo, for mathematicians, perhaps,
or the Gruska book, for Quantum Computation)).
Bruno
Brent
Are not the chlorophyl molecule doing something similar when
exploiting quantum weirdness for optimizing the use of the
photons? Can the plant "know" the precise time of the absorption
of the photons and get at the same time a similar energy optimum?
Plant would manage the energy of the sun without seeing, and
without saying, of course :)
I profit from not having read a paper on non-locality in time to
speculate wildly, sorry ....
If you have a good link on this form of non locality... (and if I
can optimize the energy and time needed ...)
Bruno
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