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Location: UFOUpDatesList.Com > 2007 > Jun > Jun 17

Re: E.S.A. Successfully Tests Real SETI Detector -

From: Martin Shough <parcellular.nul>
Date: Sat, 16 Jun 2007 18:25:14 +0100
Fwd Date: Sun, 17 Jun 2007 09:16:42 -0400
Subject: Re: E.S.A. Successfully Tests Real SETI Detector -

>From: Ray Dickenson <r.dickenson.nul>
>To: <ufoupdates.nul>
>Date: Sat, 16 Jun 2007 10:01:57 +0100
>Subject: Re: E.S.A. Successfully Tests Real SETI Detector

>>From: Martin Shough <parcellular.nul>
>>To: <ufoupdates.nul>
>>Date: Fri, 15 Jun 2007 22:35:54 +0100
>>Subject: Re: E.S.A. Successfully Tests Real SETI Detector

>>>From: Ray Dickenson <r.dickenson.nul>
>>>To: <ufoupdates.nul>
>>>Date: Thu, 14 Jun 2007 01:45:07 +0100
>>>Subject: E.S.A. Successfully Tests Real SETI Detector


>>>What the ESA release doesn't stress is that such a link might
>>>give us instantaneous interstellar communications.

>>The ESA story is about quantum cryptography, not FTL  signalling.
>>The entanglement link does not itself carry any information. It
>>carries an encryption algorithm. Nonlocal entanglement is ideal
>>for encrypted communications for the very reason that the
>>entanglement itself contains zero information.



>You're smart enough to see they can be the same thing,
>regardless of what you call them.

No, they cannot be the same thing. A quantum communications
channel is a mixed channel that requires quantum information
_and_ classical information, which is the stuff that belongs to
the "ordinary" world of local-real couplings. This is the stuff
that is useful to you, that can constitute a message signal. But
you can't get classical information out of the quantum channel
without putting classical information in. To use a quantum
encrypted channel or a quantum teleportation channel you don't
just have an instantaneous nonlocal coupling of states and,
voila, job done. To complete the channel you have to exchange
local, classical information between the two ends of the link,
and this is done, by definition, at the speed of light. There is
no (known) way around this.

>A quantum (entangled) link automatically comes with
>cryptographics as an optional extra.

>Basic set-up is a source of entangled photons (they come in
>pairs) plus at least two 'receivers' - which can be telescopes
>fitted with 'detectors' or demodulators').

>As a result of their experiment ESA now knows you can probably
>have two telescopes say sixty light-years apart and use a mid-
>way star as a source of entangled photons - stars generate them
>(in pairs) for free.

As a result ESA now knows that entangled photon states can be
used as a random quantum encryption key for ordinary light-speed
communications with satellites. This quantum comms channel is no
more "instantaneous" than any radio I'm afraid. The experiment
was just about whether the atmosphere would destroy the
entanglement over 144 km between La Palma and Tenerife. It
didn't. But to verify this the experimenters from La Palma had
to get on their bikes and go to Tenerife, or get on the phone or
wait for a postcard. As I already said, the information in the
quantum channel is not in the the entanglement itself but is
distributed in the _total_ coupling, which includes the
classical one.

>However broadcast is simplicity itself, and, given the sudden
>huge expansion of the Drake Equation, it's almost certainly
>permeating our galaxy at this time.

>And we can do most of it (rather crudely) right now. The trick
>will be tweaking our 'demodulator' to detect all potential
>signaling.  As always 'sensitivity', 'selectivity' and 'mode'
>will be the big challenges.

>I suspect that's being worked on right now - would you want to

>And, just thinking about this - if astronomers focused on a star
>at the 'edge of the universe' (the visible universe that is)
>there are some even more intriguing implications.

Your entangled stellar photons are only as much use as whatever
classical information channel you have available. You can use
them to encrypt your light-speed communications, which might be
useful; you can possibly use them for light-speed quantum
teleportation, which might be very useful. But (so far as is
known) you cannot use them to transmit messages faster than the
speed of light. For messaging purposes the quantum channel is
confined on the light cone just like any other.

Given that entanglement is probably the dominant type of
coupling in all physical systems, this fact is almost obvious.
It is implied in the very fact that the world around you is not
a coherent superposition of quantum states, but a classical
world of decohered states within a relativistic spacetime
structure. In other words, nature is shot through with EPR-type
entanglements, and her complete causal structure evidently
depends somehow on the fact that they are there, but she doesn't
use them for getting classical information from place to place.
And neither can we.

Cosmic instant messaging via entanglement is not possible "right
now" and it certainly is not "simplicity itself". It is not
possible at all. As I've also said already, that statement needs
qualifying, in that it is made without prejudice to
re-interpretations that may come from future physics. But that's
how it stands at the moment.

Martin Shough

Listen to 'Strange Days... Indeed' - The PodCast



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