From: Zenaan Harkness <zen@freedbms.net>
On Fri, Aug 05, 2016 at 09:10:42AM -0600, Mirimir wrote:
...
> Here, from <
http://www.scottaaronson.com/blog/?p=2464>:
> > The violation of the Bell inequality has a schizophrenic status in
> > physics. To many of the physicists I know, Nature’s violating the
> > Bell inequality is so trivial and obvious that it’s barely even
> > worth doing the experiment: if people had just understood and
> > believed Bohr and Heisenberg back in 1925, there would’ve been no
> > need for this whole tiresome discussion.
>Seriously, I am none the wiser and cannot yet make sense of what they
>are saying.
>China apparently is putting this experiment in space - are they winning
>a game on prediction of one particular bit with > 75% probability, and
>if so, can they run that game numerous times to get that probability
>close to 100%, and if so, can the random inputs to each side be made not
>random so that the result of the game is transmission of information?
>I cannot begin to answer any of these questions sorry...
I will explain what I think they are doing in the fiber-optic version of the experiment,
at least so nobody is permanently misled by my previous analogy.
Imagine a central location on earth, let's call it Location B. 20,500 meters west of
that is Location A, and 20,500 meters to the east of "B" is Location C. There's an
optical fiber going from "A" to "B", and another optical fiber going from "B" to "C".
Two entangled photons are produced at Location B, then one is launched into
fiber going to "A", and the other photon is launched from "B" into the fiber going to "C".
After about 100 microseconds later (since the speed of light in that fiber is about
'c'/1.4584, where 1.4584 is the index of refraction of infrared in silica, thus 205.5
meters /microsecond), those photons emerge from their respective ends. Not
necessarily at the same time, because the length of the fibers may not be quite
identical. They do the detection at Location A, and through prior arrangement they
schedule the detection at "C" a few nanoseconds later, possibly adjusting the physical
length of the fiber to get the timing close to being correct.. Good synchronization
could be achieved by GPS-controlled clocks, or perhaps a third fiber being used to
synchronize local clocks at "A" and "C".
They first detect at "A", and then detect at "C". And they might reverse the order, for
completeness. But that's not the end:
To determine that there has been more than a 50% correlation of the measured spins, they have
to transmit the type (angle) of measurement they make by ordinary optical fiber. (Although,
it wouldn't have to be on an optical fiber: It could be a USB memory stick glued to the
shell of a fast snail, I suppose. the important thing is that the information eventually gets
to the other side, not how fast it takes to get there.)
The information eventually gets to the other end, and they do the calculations and
verify that SOMEHOW, the fact that a measurement at "A" somehow affected the
measurement at "C". If they "schmoo plot" (meaning carefully adjust, then plot on a graph)
, they can determine how fast some affecting particle or signal would have to travel to affect the receiver at the
other end. Since the delay from Location "A" to "Location "C" would be (100+100) = 200 microseconds
in a fiber, it would be 200/1.4584 = 137.136 microseconds from location A to location C,
by air. (or in a vacuum, or by radio, etc.)
That figure I found from an article a few years ago, that said it would have to travel at
least 10,000x that of 'c' to affect the measurement, would require that the delay is measured by:
137.136 microseconds/10,000 = 13.7126 nanoseconds. If the measurement at "A"
occurred only 13.7136 nanoseconds before the measurement at "C", and yet there was
still correlation, this shows that a velocity of at least 10,000 'c' to affect the outcome at "C".
Therefore, I conclude that it would be easy to measure the minimum effective speed of the
hypothetical interfering particle or wave. That particle or wave would have to travel 41,000
meters in less than 13.7 nanoseconds, to achieve that interference. Time measurement to 1
nanosecond is easy, to 1 picosecond is doable, and in fact measurement of time values
far less than 1 picosecond can be accomplished.
Jim Bell