Wang / Sagnac Devices [Relativity]

Prev: Relativity ring problem - what shape is this?
Next: BUY CHEAP TEXTBOOKS | College Textbooks | Used Textbooks |

From: Dono. on 17 Oct 2009 10:56

On Oct 16, 11:08 pm, tominlag...(a)yahoo.com wrote:
> On Fri, 16 Oct 2009 09:01:34 -0700 (PDT), "Dono." <sa...(a)comcast.net>
> wrote:
>
>
>
> >On Oct 16, 8:43 am, tominlag...(a)yahoo.com wrote:
> >> On Fri, 16 Oct 2009 08:31:15 -0700 (PDT), "Dono." <sa...(a)comcast.net>
> >> wrote:
>
> >> >On Oct 16, 8:08 am, tominlag...(a)yahoo.com wrote:
>
> >> >> In the Ritz/Waldron model, a mirror is not a new source, and therefore
> >> >> light may or may not be reflected at c with respect to it. Its speed
> >> >> after reflection is based on any relative motion between the source
> >> >> and the mirror. If there is no relative motion, the reflected photon
> >> >> will be moving at c; if there is relative motion, v, its speed will be
> >> >> c +/- v all with respect to the mirror.
> >> >> Regards,
> >> >> Tom Miles
>
> >> >If the speed is ANYTHING but c, the model fails BOTH the Sagnac and
> >> >the Ives experiments.
>
> >> I suspect you are referring to the passive type of interferometer
> >> devices. In that case, you are wrong: whatever the speed of the
> >> initial ray of light, components going in each direction after
> >> splitting will have the same speed, be it c or u. The outcome is the
> >> same. As a practical matter, since the sources in the experiments you
> >> cite are not in motion with respect to the device, the speed will be
> >> c.
>
> >Prove it . Show the math.
>
> I don't know what there is to prove. First, please let me know which
> Ives experiment you are discussing.

Ives-Stilwell.

> I was not aware of an Ives
> experiment that tested the Sagnac effect.

Who told you that? I told you that all flavors of the ballistic theory
are disproved by the Ives experiment AND by the Sagnac experiment.
Prove that this isn't so.

> The point I was trying to make was simply that whatever the speed of
> the incoming ray was, that speed was retained by the two components
> after the ray is split.

Irrelevant, you need to write the equations of the complete
experiment. If you ever manage to do that (I doubt it), you will find
out that you are wrong: Ives, Sagnac, Fizeau experiments all falsify
the ballistic theory. So does MMX in a medium with refraction greater
than 1.

From: Androcles on 18 Oct 2009 06:44

"Androcles" <Headmaster(a)Hogwarts.physics_p> wrote in message
news:kSmCm.7213$sl7.1021(a)newsfe18.ams2...
>
> Job done.

Since Laguna Tommy is talking to himself, I may as well do the
same. However, I have no need to change what I said so I've
deleted it instead. I need the snipping practice, others are so
much more skilful at it than I.

From: tominlaguna on 18 Oct 2009 08:34

On Sat, 17 Oct 2009 09:33:44 -0400, Jonah Thomas <jethomas5(a)gmail.com>
wrote:

>tominlaguna(a)yahoo.com wrote:
>> Jonah Thomas <jethomas5(a)gmail.com> wrote:
>> >tominlaguna(a)yahoo.com wrote:
>> >
>> >> Sue posted a link to a Wang & et al paper which describes their
>> >fiber> optical gyro (FOG) experiments. That paper has been
>> >superseded by:> http://arxiv.org/ftp/physics/papers/0609/0609235.pdf.
>> > This latest
>> >> paper provides a more detailed account of that work.
>> >> Figure 3 of the new Wang paper shows that when a linear section of
>> >the> FOG is moved in translation, there is a fringe shift that is
>> >> proportional to the length of that section and the speed of its
>> >> motion. Most people that I have discussed this with believe that
>> >Dr.> Wang has demonstrated that his design can detect translational
>> >motion.> I disagree. They measured the acceleration of the fiber
>> >section from> zero to some constant velocity.
>> >
>> >Here is why I think there is something else going on too.
>> > ________________
>> >/ \
>> >\____x___________/
>> >
>> >Here is the simple form of the Wang experiment, with the
>> >emitter-detector x traveling around the loop. When x is on the linear
>> >section traveling at constant speed they get the same phase shift
>> >that they do when it is going around the rollers.
>> > ___________________________________
>> >/ \
>> >\____x______________________________/
>> >
>> >When they change the length and change nothing else, they get a
>> >change in phase shift proportional to the length. How has this
>> >changed the acceleration proportional to the phase shift? Presumably
>> >the light is getting accelerated when it goes around the rollers, but
>> >why is it more acceleration because of the extra length? They tried a
>> >version where there was no extra Sagnac-area enclosed, too.
>> >
>> >> The Wang paper has lead me to conclude that the "Sagnac effect" is
>> >a> phenomenon peculiar to situations when the source and/or receiver
>> >are> experiencing acceleration.
>> >
>> >I think that's true, because it requires a closed path and how are
>> >you going to get a closed path without changing the direction of the
>> >light? And how can you do that with no acceleration? But I don't yet
>> >see that the effect is proportional to the acceleration. It's
>> >proportional to the linear speed and to the length of the moving
>> >fiber.
>
>> In the diagrams you have presented, it appears you are describing an
>> experiment shown in the earlier paper cited by Sue. Please look at
>> the paper I referenced; specifically Fig. 3. For that test, neither
>> the source nor the receiver was moving; it was only a straight section
>> of fiber that was translated. So you have: 4 meter (or whatever the
>> exact size was) loop of fiber, stationary source, stationary receiver,
>> yet a Sagnac signal generated when you move a section of the loop.
>> That seems to defy logic since light traveling in opposing directions
>> still has to cover the 4 meter distance each way while traveling at c;
>> same speed in each direction, same distance to travel, but different
>> arrival times. There is obviously a change in the optical path length
>> since the physical path length remains unchanged. I contend that is
>> produced by acceleration; similar to the way the bullet path length is
>> changed in the dueling analogy.
>
>I can easily believe that you are talking about something that was
>produced by a change in acceleration.

No, I was talking about a change in velocity.

>But the effect that I pointed out from the first paper does not appear
>to me to have different acceleration, and yet they got a phase
>difference. So I think there is something other than acceleration going
>on to get the Wang effect. Or possibly there is a hidden acceleration
>that I haven't noticed. Maybe somehow if you use rollers with the same
>radius rotating at the same speed, it puts a bigger acceleration on the
>fiber if the fiber is a longer length?

Perhaps we first need to discuss Sagnac Effect and Sagnac Instruments.
The Sagnac Effect, in my opinion, occurs when there is acceleration
associated with the source, receiver and/or conduit. It is
acceleration that produces a change in the optical path length; just
like the arrow path length was changed while traversing the 100 ft
long train car when the car was accelerated.
Now the Sagnac Instruments. There are two classifications (when we
eliminate the one-way Sagnac Effect): (1) The first is the "passive
design" which is typically configured as an interferometer. This
class was the type used by Sagnac, Michelson-Gale, Dufour-Prunier,
etc. You can have the sources and/or receivers rotating or not
rotating, you get the same fringe shift. (2) The second class is the
more modern, "active design". In this design, the lasing tube is
rotating. This class was used by Macek-Davis and Stedmann. It is
also the design most commonly used for aerospace and naval
instrumentation.
For the passive design, you can only detect "changes" in rotation. It
is not a tachometer. If I hid the device from you and only showed you
the fringe indicator, you would have no way of knowing if the device
was rotating or not, let alone at what speed. If I showed you that
indicator during a fringe shift, there is no way for you to tell if
the platform went from, say, 0 rpm to 2 rpm, or it went from 2 rpm to
4 rpm because the magnitude of the fringe shift would be the same.
The active design operates quite differently. Here, the lasing tube
and the conduit are in rotation together. When rotating, they are
continually experiencing a change in tangential velocity
(acceleration) which produces a change in the optical path length.
Since the lasing tube can only resonate at whole numbers of
wavelengths, it is continually adjusting the wavelengths of the
forward and aftward emissions to accommodate for any changes in
optical path length. The wavelength differences produce a beat
frequency which can be measured by a heterodyne detector. So, the
active design is a tachometer, and can in fact give you a true, real
time reading of angular velocity.

>> When I first thought about the reported results, I understood the
>> source of the fringe shift to be a change in the enclosed area. But
>> upon looking at the diagram and seeing the linearity of the plots, I
>> concluded that area change was not a factor, otherwise the data plot
>> would not be linear for the various tested speeds.
>
>Agreed.
>
>> Translational speed by itself is not a factor just as it is not a
>> factor in the dueling analogy, where both shooters would die at the
>> same time when the train was moving at constant speed.
>
>Translational speed looks like a factor in the one I mentioned, once you
>accept that area is not a factor.

The Wang setup described in each paper is a passive design. It only
can record "changes" in velocity. I know it looks like a velocity
meter, but it is only recording changes in velocity of the conduit. It
is much like the speedometer on your car: you look at the gauge and it
is reading 20 mph. I look at the gauge and I conclude it has recorded
your change in velocity from 0 to 20 mph. It remains pinned at 20 mph
until you accelerate or decelerate.

From: tominlaguna on 18 Oct 2009 08:35

On Sat, 17 Oct 2009 07:56:20 -0700 (PDT), "Dono." <sa_ge(a)comcast.net>
wrote:

>On Oct 16, 11:08 pm, tominlag...(a)yahoo.com wrote:
>> On Fri, 16 Oct 2009 09:01:34 -0700 (PDT), "Dono." <sa...(a)comcast.net>
>> wrote:
>>
>>
>>
>> >On Oct 16, 8:43 am, tominlag...(a)yahoo.com wrote:
>> >> On Fri, 16 Oct 2009 08:31:15 -0700 (PDT), "Dono." <sa...(a)comcast.net>
>> >> wrote:
>>
>> >> >On Oct 16, 8:08 am, tominlag...(a)yahoo.com wrote:
>>
>> >> >> In the Ritz/Waldron model, a mirror is not a new source, and therefore
>> >> >> light may or may not be reflected at c with respect to it. Its speed
>> >> >> after reflection is based on any relative motion between the source
>> >> >> and the mirror. If there is no relative motion, the reflected photon
>> >> >> will be moving at c; if there is relative motion, v, its speed will be
>> >> >> c +/- v� all with respect to the mirror.
>> >> >> Regards,
>> >> >> Tom Miles
>>
>> >> >If the speed is ANYTHING but c, the model fails BOTH the Sagnac and
>> >> >the Ives experiments.
>>
>> >> I suspect you are referring to the passive type of interferometer
>> >> devices. In that case, you are wrong: whatever the speed of the
>> >> initial ray of light, components going in each direction after
>> >> splitting will have the same speed, be it c or u. The outcome is the
>> >> same. As a practical matter, since the sources in the experiments you
>> >> cite are not in motion with respect to the device, the speed will be
>> >> c.
>>
>> >Prove it . Show the math.
>>
>> I don't know what there is to prove. First, please let me know which
>> Ives experiment you are discussing.
>
>Ives-Stilwell.
>
>> I was not aware of an Ives
>> experiment that tested the Sagnac effect.
>
>Who told you that? I told you that all flavors of the ballistic theory
>are disproved by the Ives experiment AND by the Sagnac experiment.
>Prove that this isn't so.
>
>
>> The point I was trying to make was simply that whatever the speed of
>> the incoming ray was, that speed was retained by the two components
>> after the ray is split.
>
>
>Irrelevant, you need to write the equations of the complete
>experiment. If you ever manage to do that (I doubt it), you will find
>out that you are wrong: Ives, Sagnac, Fizeau experiments all falsify
>the ballistic theory. So does MMX in a medium with refraction greater
>than 1.
>
Sorry, we're discussing Wang and Sagnac...

From: tominlaguna on 18 Oct 2009 09:41

On Sun, 18 Oct 2009 11:44:30 +0100, "Androcles"
<Headmaster(a)Hogwarts.physics_p> wrote:

>
>"Androcles" <Headmaster(a)Hogwarts.physics_p> wrote in message
>news:kSmCm.7213$sl7.1021(a)newsfe18.ams2...
>>
>> Job done.
>
>Since Laguna Tommy is talking to himself, I may as well do the
>same. However, I have no need to change what I said so I've
>deleted it instead. I need the snipping practice, others are so
>much more skilful at it than I.
>

Correction to last post re Langevin: ...that Sagnac was compatible
with SRT.