Re: Some day a SRQ correspondent will come along who actually understands me

In article <7kju5oF38dcdhU1@xxxxxxxxxxxxxxxxxx>,
Yowie <yowie9644.DIESPAMDIE@xxxxxxxxxxxx> wrote:
"Ian Davis" <ijdavis@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:hc26sa$id0$1@xxxxxxxxxxxxxxxxxxxx
*snip*

The delayed quantum choice eraser experiment is described at:
http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

The experimental results demonstrate that under special circumstances
a later action can contribute to an earlier effect. In this
experiment photons randomly take a path which 50% of the time because
of the geometry
of the random path taken permits determination of which slit the
photon
passed through, and 50% of the time gives no information of which
slit the photon passed through. Its entangled twin strikes a screen
and where it strikes the screen is recorded. Subsequently it is
determined that considering only those photons for which path
knowledge has been erased
the twins form a defraction pattern on the screen, while for the
remaining photons (for which path knowledge is not erased) their
twins produce no
such pattern on the screen. The strangeness is in the fact that the
time
it takes the photon to traverse the path it takes is longer than the
time it takes the twin to reach the screen where its position is
recorded.

Possible explanations:
1. The path taken results in a signalling backwards in time to the
twin.
2. The twin signalling forwards in time whether it decided to
defract or not refact.
3. The measured position not being definite or decided by the
hardware that detects that position and which records it in a
computer, but only know when examined.

1 is counter to common sense.
2 is counter to the fact that the path taken can be interfered with
so any signalling forward in time what the photon travelling the
path must do can be defeated by the experimenter (unless one
presumes that such choice is no more permitted than the choice to go
back in time and kill ones parent before one is born)
3 is counter to common sense and raises the interesting question of
whether one could physically capture and examine data from the twin
before the other photon had traversed its random path, so as to rule
out any vagueness in that data. Clearly if one make the path taken
long enough there would be time enough to do so.

4. There is only 1 photon in the universe, it just gives the illusion that
there's many. :-)


Actually yes, that issue is close to a question I asked after a presentation
at the perimeter institue shown below:

http://www.q2cfestival.com/play.php?lecture_id=7738

I asked Robert Spekkens whether the game he played on stage to demonstrate the
basics of Bells inequality cheated because it had the photons moving apart
and becoming separated by space and time. Special relativity says that for
things travelling at the speed of light time stops. Though I've never quite
got my head around this notion, nor how light for which time has stopped could
have anything approximating a frequency, it does seem to me that if time
stops this means that events can't be separated for the thing that time has
stopped for in time, and since obtaining spacial separation requires time
space too must somehow stop or collapse to a fixed point. He indicated that
he hadn't thought of things this way himself and really couldn't give an
answer to this question.

Afterwards I realised that I had asked the wrong question. The key question
is whether bells inequality could also be produced for quantum objects like
electrons rather than light which travelling slower than light speed do
experience spacial and temporal separation.

Do you have any idea what it would be like to live in a world where time
stopped.

Ian
.

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