[ExI] R: Re: R: Re: Cramer on impossibility of FTL communication
scerir at alice.it
scerir at alice.it
Wed Sep 2 22:48:43 UTC 2015
Adrian Tymes wrote:
Let us take this one step further.
Let us posit the existence of some universal observer. Let us call it God,
because God knows all.
God sees two entangled photons being formed, and knows their properties.
God does not tell you, but God knows.
Some time later, you find out the state of one of them. Does this cause a
change in the other? No: it is still as God always knew it was, and a
chain of knowledge can be traced back to the origin when the two photons
were at the same place so as to get entangled.
It is ok. I'm not saying there are physical "influences" between
the entangled particles (timelike separated or spacelike separated).
There are papers showing that *if* there are such "influences"
the speed of these "influences" are superluminal (but non infinite).
In general experiments performed use Franson interferometers
(time / energy entanglement, not position momentum entanglement).
The final results of the experiments, with moving measuring devices,
rule out the possibility to describe the quantum correlations by means
of real clocks, in terms of "before" and "after".
Nonlocal quantum phenomena cannot be described with the notions
of space and time. This means that there is no time ordering behind
nonlocal correlations, so the causal order cannot be reduced to the
temporal one. Quantum correlations somehow reveal dependence
between the events, or logical order. Experiment shows that this
dependence, or logical order, is beyond any real time ordering.
In the realm of the nonlocal quantum phenomena, things come
to pass but the time doesn't seem to pass here.
What about these experiments? When they are performed with moving
apparatuses, several relevant frames are involved. In this case, different
clocks watch the arrival times, and what is “after” according to the
clock may become “before” according to one moving clock. Then, it is possible
to define other time orderings. If each measuring device in its own reference
frame is the first to select the output of photons, we have "before-before"
If each measuring device in its own reference frame selects the photon
output after the other, we have the "after-after" timing. Is it possible to
a time-ordered causal explanation for relativistic experiments using
in motion? No, quantum mechanics requires that the particles stay non local,
correlated independent of any timing,both in the "after-after" and in the
"before-before" situation. Experiments performed agree with quantum
So, if these correlations are out of space and time, there are - perhaps -
"correlations without correlata" (according to Mermin and his Ithaca
interpretation) that is to say there is an algorithm, an abstract law of
nature, wich regulates these correlations, period. And that is (imo)
close to you are saying.
A common cause (overlap of the light cones of both
entangled particles) could explain correlations?
There is no general agreement about that.
As for the "conspiracy" argument, Shimony, Horne
and Clauser argue against conspiracy theories on
the basis that the rejection of independence of results
is a kind of skepticism, and that “skepticism of this sort will
essentially dismiss all the results of scientific experimentation”.
"It has been argued that quantum mechanics
is not locally causal and cannot be embedded
in a locally causal theory. That conclusion
depends on treating certain experimental parameters,
typically the orientations of polarization filters,
as free variables. But it might be that this apparent
freedom is illusory. Perhaps experimental parameters
and experimental results are both consequences,
or partially so, of some common hidden mechanism.
Then the apparent non-locality could be simulated."
- John Bell, "Free Variables and Local Causality",
'Epistemological Letters', 15, (1977
More information about the extropy-chat