In article ,
Spike wrote:

If that is so, then the possibility of a communication channel must
exist, the transmission mechanism of which is being used by the
particles .

It doesn't "must" exist.

The possibility of a comms system must exist using this effect. That the
engineers haven't found a way to exploit it is a different issue.

I think that if you study how entanglement and quantum particles
actually work, you'll understand that this is *not* the case.

A good question to ask here is: what is this change that takes place? It
is clearly measurable.

Here's a good video-and-animations explanation of the entanglement,
how we know it exists, and why it cannot be used to transmit
classical information faster than the speed of light.

https://www.youtube.com/watch?v=ZuvK-od647c

To sum it up: it's clearly measurable, but in order to show that it's
happening at all, you need to *compare* two sets of measurements - one
taken at each end of the experiment.

You cannot "see" the effect by looking only at the measurements taken
at one end of the experiment. Due to the nature of quantum mechanics,
the measurements taken at one end look entirely random.

The measurements you take at the other end of the experiment look
equally random, at the time that you take them.

It's only when you compare the two sets of measurements, that you can
see that they're "random, but opposite". And, you can't compare them
without sending one set of measurements to the other end of the
experiment... and this can't be done faster than lightspeed.

If the effect acts instantaneously over large distances, why can it not
be exploited?

What "effect" exactly?

You'll need to ask that of the PP, as he used the word in his
explanation. I was thinking of a comms system that uses the effect
(whatever it is) to transfer information.

See the video I posted, above, for a pretty good explanation of what
the effect is, and why it doesn't help us send messages faster than C.

On 9/16/2015 12:38 PM, Dave Platt wrote:
In article ,
Spike wrote:

If that is so, then the possibility of a communication channel must
exist, the transmission mechanism of which is being used by the
particles .

It doesn't "must" exist.

The possibility of a comms system must exist using this effect. That the
engineers haven't found a way to exploit it is a different issue.

I think that if you study how entanglement and quantum particles
actually work, you'll understand that this is *not* the case.

A good question to ask here is: what is this change that takes place? It
is clearly measurable.

Here's a good video-and-animations explanation of the entanglement,
how we know it exists, and why it cannot be used to transmit
classical information faster than the speed of light.

https://www.youtube.com/watch?v=ZuvK-od647c

To sum it up: it's clearly measurable, but in order to show that it's
happening at all, you need to *compare* two sets of measurements - one
taken at each end of the experiment.

You cannot "see" the effect by looking only at the measurements taken
at one end of the experiment. Due to the nature of quantum mechanics,
the measurements taken at one end look entirely random.

The measurements you take at the other end of the experiment look
equally random, at the time that you take them.

It's only when you compare the two sets of measurements, that you can
see that they're "random, but opposite". And, you can't compare them
without sending one set of measurements to the other end of the
experiment... and this can't be done faster than lightspeed.

Good explanation. The point taken away from this is that the principle
of "spooky action at a distance" doesn't violate any laws we currently
hold to be true, partly because of the simultaneity issue. The speed of
light also sets a limit to how well you can establish the precedence of
events. The concept of simultaneous becomes "fuzzy" as limited by the
distance separating the two events. In some situations it becomes
impossible to say which of the two observations were first and so
clearly information can not be conveyed since the direction would depend
on which event was first.

--

Rick

On 16/09/2015 17:38, Dave Platt wrote:
In article ,
Spike wrote:

A good question to ask here is: what is this change that takes place? It
is clearly measurable.

Here's a good video-and-animations explanation of the entanglement,
how we know it exists, and why it cannot be used to transmit
classical information faster than the speed of light.

https://www.youtube.com/watch?v=ZuvK-od647c

To sum it up: it's clearly measurable, but in order to show that it's
happening at all, you need to *compare* two sets of measurements - one
taken at each end of the experiment.

You cannot "see" the effect by looking only at the measurements taken
at one end of the experiment. Due to the nature of quantum mechanics,
the measurements taken at one end look entirely random.

The measurements you take at the other end of the experiment look
equally random, at the time that you take them.

It's only when you compare the two sets of measurements, that you can
see that they're "random, but opposite". And, you can't compare them
without sending one set of measurements to the other end of the
experiment... and this can't be done faster than lightspeed.

Thanks for the video link. I wish physics had been presented like that
in my day...but it wasn't. It's interesting to note that in a couple of
places, the presenter said something like "... most scientists agree
that...", which implies that there may well be other qualities of the
particles that are not understood at this time - and which could be
exploited.

--
Spike

"Nearly all men can stand adversity, but if you want to test a man's
character, give him power" - Abraham Lincoln

On 17/09/2015 08:55, Spike wrote:
On 16/09/2015 17:38, Dave Platt wrote:

Here's a good video-and-animations explanation of the entanglement,
how we know it exists, and why it cannot be used to transmit
classical information faster than the speed of light.

https://www.youtube.com/watch?v=ZuvK-od647c

Thanks for the video link. I wish physics had been presented like that
in my day...but it wasn't. It's interesting to note that in a couple of
places, the presenter said something like "... most scientists agree
that...", which implies that there may well be other qualities of the
particles that are not understood at this time - and which could be
exploited.

Looking through the video a second time, one of the contributors says
something like "...It's almost as if there's someone standing behind it,
playing us a trick". I took this to mean that while the gross,
measurable, properties have been accepted, there is more to this that
has yet to be discovered. It might well happen that a deeper knowledge
will reveal some property that could result in this being the basis of a
communications system or a matter transporter.

I'm struck by the comparison between this and the atomic physics of the
era when the state of knowledge of the latter amounted to that related
to protons, neutrons, and electrons.


--
Spike

"Nearly all men can stand adversity, but if you want to test a man's
character, give him power" - Abraham Lincoln