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On Fri, Dec 06 2013, brian carroll wrote:

>> "Spooky action" entanglement has been measured to operate at a velocity of
>> at least 10,000 'c', where 'c' is the speed of light in a vacuum.  (signals
>> transmitted on optical fibers about 20 kilometers apart.)  Unfortunately,
>> there does not appear to be any way to employ this to transmit information.
>>        Jim Bell


> so would this not break the physics model already, of faster than light info,
> such that the cosmos may operate on principles beyond those employed.

> the comments on the article seemingly indicative of this same scenario,
> as if a realm of political science, gerrymandering of physics seemingly.

> if a spin could be remotely connected to another, as mentioned in the
> article comments, and activated at a distance, could this not function
> as a basic switch, perhaps making a relay or gate or some kind or the
> ability to send/receive coded messages via morse code (as mentioned).

> say, a sequence of spins encoding the alphabet or whatever, perhaps
> controlled by a normal computer process yet transmitted/received via
> this quantum connectivity (seemingly out of this world then back into it
> via vibration, rather than a line of sight acoustic signal, if understanding)

> i thought that was the idea underneath the potential for other, hidden
> technology embedded in existing systems, that remote relationship
> via quantum properties that operate in other dimensionality/structures,
> if not beyond lightspeed properties or conceptions, and that it may not
> be recognizable in the existing approach or computational paradigm.
> such that fiber may not be necessary, the approach to key exchange
> or processing may occur in other parameters or functional structures.

(Take everything I say here with a grain of salt; I'm not a quantum
physicist, nor have I ever even taken a quantum physics class. I just
read a lot about this stuff and think about it a lot.)

Quantum entanglement is inherently difficult to explain because it's a
consequence of the prevailing interpretation (the Copenhagen
interpretation) of quantum mechanics, that the spin axis isn't actually
"chosen" until you measure it. Unfortunately, the information that's
supposedly "transmitted" instantaneously doesn't originate from outside
the system, so it can't be used to send anything useful to human beings.

There's an explanation that's slightly less awkward in my view: that the
information about what axis you're measuring the spin on actually gets
transmitted backward in time along the particle's path to the point at
which the particles became entangled. It's less awkward because it
doesn't require anything to happen faster than light, and it doesn't
allow paradoxes because you can't actually get anything useful back
out. This interpretation is known as "time symmetric quantum mechanics,"
but unfortunately there aren't a whole lot of papers on it because the
Copenhagen interpretation is quite dominant.

Special Relativity itself actually doesn't forbid traveling or sending
information faster than light; it just forbids accelerating a massive
object to or through the speed of light. There has been talk of
"tachyons," particles "born" traveling faster than light and possessing
imaginary mass, since the earliest days of SR. Since they would allow
the creation of paradoxes and have other strange properties such as
accelerating as they lose energy, most physicists assume they do not
exist. They've even created a principle, the "Causality Principle," that
forbids them. The Causality Principle simply says that all observers
must observe two events that are causally connected (i.e. exchange any
information between them) occurring in the same order. This property can
only be true if information is transmitted at or below the speed of
light.

The Causality Principle is the weakest principle that prevents paradoxes
within Special Relativity, but it turns out a minor tweak to SR enables
a weaker principle to prevent paradoxes: the addition of a "privileged"
refernce frame. In particular, the reference frame in which quantum
entanglement is assumed to operate, which may also be the reference
frame of the cosmic microwave background. The revised, weaker Causality
Principle says that any two causally-connected events must be observed
to occur in the same order *to an observer in the privileged reference
frame.* That gets rid of the speed of light limit entirely, as long as
you don't travel back in time in this one particular reference frame. It
would probably also make the Copenhagen interpretation of QM preferable
to the time-symmetric interpretation, but I haven't thought that one
through yet (in fact, I don't understand how they measure the speed of
the quantum connection yet either).

That means quantum entanglement *could* actually carry useful
information, and we could (in theory, anyway) construct an Ansible.

Before you go off saying "but SR says there's no privileged reference
frame!" it actually doesn't. It says you don't *need* one. Lorentz
constructed the geometry Einstein borrowed for Special Relativity
specifically to explain why the Earth's motion relative to the
luminiferous ether could not be detected. Einstein's major contribution
(for SR, aside from E=mc^2) was the realization that Lorentz's geometry
obviated the need for a luminiferous ether entirely. But perhaps quantum
entanglement can give the luminiferous ether a new life.

-- 
Sean Richard Lynch <[email protected]>
http://www.literati.org/~seanl/
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