[ExI] frame dragging confirmed, so what of QT?
scerir at alice.it
Sun Jun 19 17:55:30 UTC 2011
From: "Damien Broderick"
> "Gravity Probe B Project Confirms Einstein Space-Time Ideas"
> but doesn't this imply that QT is *less* secure, since GR and QT are incommensurable if
> not incompatible?
The usual expression is "peaceful coexistence" between QT & Relativity (or between
quantum nonlocality-nonseparability and relativistic locality).
There are at least a couple of interesting point: is there a (cosmic) preferred reference
Here below something written by Nicolas Gisin.
"Indeed, one can prove that there are 3-party scenarios in which any explanation of
correlations based purely on hidden communication (at any nite speed), hence without any
additional local variable lambda, would allow one to signal faster than light. The
argument runs as follows.
Imagine that the 3 players, Alice, Bob and Charlie, share a GHZ state of 3 qubits:
(|000> + |111>) / 2^-1
Alice is far both from Bob and from Charlie. Bob and Charlie are not as far from each
other, but still far enough that their input-outcome events are space-like separated.
Further, imagine that Bob and Charlie synchronize their events so well that there is no
time for the hidden communication to inuence each other. Consequently, if Alice does
nothing, but Bob and Charlie measure their qubits in the standard [|0>,|1>] basis, then
they observe random and uncorrelated outcomes. Indeed, all qubits are locally in a random
state and there is, by assumption, no time for any influence (even at a speed possibly
than light, but finite). If, however, Alice makes a measurement, also in the standard
basis, long enough before Bob and Charlie (in the PRIVILEGED REFERENCE FRAME) so that
the hidden communication from Alice to Bob and to Charlie has time to arrive, then Bob and
Charlie's outcome are correlated: they are both equal to Alice's outcome. Hence, if Bob
and Charlie compare their results, they know whether Alice made a measurement or not, i.e.
there is signaling from Alice to (Bob,Charlie). Note that comparing Bob and Charlie's
result takes some time, but since Alice could be arbitrarily far away, there is clearly a
possibility that the signaling from Alice to (Bob,Charlie) is faster than light."
The other interesting point under discussion is that QM might have little to do with
space-time (ordinary space-time causality). And, according to Kent, Elitzur, etc.,
one could also speak of non-local space-times, given certain quantum nonlocal gedanken
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