[ExI] R: Re: Cramer on impossibility of FTL communication
atymes at gmail.com
Wed Sep 2 18:57:02 UTC 2015
On Sep 2, 2015 11:07 AM, "scerir at alice.it" <scerir at alice.it> wrote:
> If you have a source of entangled photons and this source is much much
> location A than to location B, and if A and B are close enough, an
> could jump from A to B and you can imagine he could perform magic tricks.
No I can't. (Not any he could not already perform, anyway.) He knows what
the photons at B will be before anyone who was previously there has
directly measured them. So what? It is known he hopped from A and could
have picked up the information there.
Also, his hops are limited to light speed.
> In other words ... in general the problem arises because obsevers are
> local, and quantum correlations are not. But if you have ... nonlocal
> observers ....
...which you don't.
> No story in space-time can describe nonlocal correlations: we have no tool
> in our story-toolbox to talk about nonlocal correlations (Gisin). Hence,
> we usually say things like "event A influences event B", or
> "event A has a spooky action at a distance on event B" or
> "event A causes a collapse of the wavefunction at location B".
> But we know that this is all wrong: there is no time ordering between the
> events A and B ("acausality").
More to the point, A and B are both caused by Z.
Event A does nothing at location B, period.
Event A causes people at A to know something about B by logical inference.
This itself does not actually do anything at B. The knowledge about what
is at B can not reach B at faster than light.
This applies to nonquantum things too. Let us say you have a bag of 15
apples. I take some number and leave. Some time later, you count and find
you have 10 apples. You thus know I took 5, but does that measurement
actually cause anything at my location to happen? It does not. I had
taken 5 apples all along; that you have measured this does not now cause
that fact to spring into being, but only to become known to you.
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