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Re: Ballistic Theory and the Sagnac Experiment

Subject: Re: Ballistic Theory and the Sagnac Experiment
From: "George Dishman"
Date: Sat, 25 Mar 2006 18:14:42 -0000
Newsgroups: sci.astro, sci.physics.relativity, sci.physics
"Jeff Root" <jeff5@xxxxxxxxxxxx> wrote in message 
news:1143301284.375826.40780@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> George Dishman replied to Henri Wilson:
>
>>> But I have never claimed that this is the major contributor
>>> to the sagnac effect. For one thing, I have shown that two
>>> beams leaving the splitting mirror 45 apart do not recombine
>>> at the one point.
>>
>> And I have pointed out many times that that has
>> no effect on the time difference whatsoever.
>
> Am I correct in understanding that the extremely tiny
> offset of the two lines in Henry's program is due to a
> trivially minor rounding error in the calculations?
> Probably caused by measuring a distance in pixels?

I suspect it is because he changes the direction
of the beam when it hits the mirror using a test
of whether it is beyond and then moves off in the
new direction from that point. To get perfect
accuracy he would need to calculate the impact
point which would be between samples. Increasing
the sample rate reduces the effect but it is a
side issue anyway, he should be showing an extended
wavefront, not a point.

>> The simple way is to move the loop along one arm and
>> measure the slope of the phase difference as a function
>> of distance.
>
> I think Henry doesn't realize how easy your version of
> the experiment is.  Moving the loop is trivial.  I think
> two people working together-- Henry and an assistant--
> could put the whole thing together, get the measurements,
> and take it down inside of eight hours.
>
> Do you agree, or have I missed something?

Depends on how he measures the phase difference
and how long it takes him to make the directional
coupler but it would take longer as he'd probably
have to buy the fibre and that would mean finding
a source of the right stuff. That means first
working out what the spec of the fibre is that he
needs. Then there's a light source and some optics
and a bit of clamping of the fibres to prevent
movement. It would take some time and money but it
isn't difficult.

George



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