Wang / Sagnac Devices
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From: Jonah Thomas on 16 Oct 2009 15:35 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 That paper has been superseded by: 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. > Saburi in 1976 demonstrated that there was a radio signal > transit time difference east-west between two earth-stationary > receiver/transmitters. Interesting! Did they measure whether the effect was the same in the morning and evening? While looking for Saburi I found this which may be of some interest: http://adsabs.harvard.edu/full/1986IAUS..114..299A
From: tominlaguna on 17 Oct 2009 02:08 On Fri, 16 Oct 2009 09:01:34 -0700 (PDT), "Dono." <sa_ge(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. I was not aware of an Ives experiment that tested the Sagnac effect. 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. In other words if the incoming ray is c, the two components will be c after splitting, not c+v and c-v as they travel in opposite directions around the device. Further, for all practical purposes the speed of light is always c in the earth-bound laboratory when there is no relative motion between the source and the receiver. Even if you used an extraterrestrial source of light, the speed of the light reaching the lab would measure at c due to the extinction process while passing through the atmoshpere.
From: tominlaguna on 17 Oct 2009 02:37 On Fri, 16 Oct 2009 16:39:37 +0100, "Androcles" <Headmaster(a)Hogwarts.physics_p> wrote: > ><tominlaguna(a)yahoo.com> wrote in message >news:to2hd5pm6nvm8qdul7kecjf5do7imn1ng5(a)4ax.com... >>I missed the opportunity to comment on this subject when a thread was >> started by Jonah Thomas last month. I hope to continue the discussion >> from this new starting point. >> 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. >> 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. There are "Sagnac devices" that can detect >> that phenomenon, but they should not be confused with the phenomenon >> itself. Examples of the devices are: the passive Sagnac >> interferometer devices of Sagnac, Pogany, Michelson-Gale, and >> Dufour-Prunier; the active Sagnac interferometer devices of >> Macek-Davis, Stedmann, modern laser gyros; and finally the "one-way" >> Sagnac system of devices known as GPS. >> A simple analogy of the phenomenon can be understood by this example: >> Assume you have a long freight car, 100 feet long. There is a dueler >> located at each end with identical guns, ammo and skill. If the car >> is stationary with respect to the rails or moving at a constant >> velocity and both fire their guns at the same time, they both die at >> the same time. But, if the train happens to accelerate forward while >> the bullets are in flight, the guy at the rear of the car dies first. >> The same thing would occur if the car was experiencing acceleration >> throughout the gun fight. That, in my opinion, is the phenomenon of >> Sagnac. Bullets are flying in two directions covering an equal >> distance of 100 feet, but one arrives sooner than the other due to the >> acceleration of the receiver. >> Paul Anderson was describing a type of device while he thought he was >> describing the effect. The generalized Sagnac effect does not deal >> with enclosed areas and angular velocity; several detection devices >> are based on those criteria, but the phenomenon is not exclusive to >> them. Saburi in 1976 demonstrated that there was a radio signal >> transit time difference east-west between two earth-stationary >> receiver/transmitters. The GPS network is corrected each day to >> adjust their clocks so that the one-way transmission of signals is >> accurate due to the Sagnac effect. Paul also suggested the Wang >> experiment was a modified Fizeau experiment. They used both hollow >> fibers and solid cross-section fiber and got the same readings. Others >> in the past, Pogany and Harress, investigated the use of glass prisms >> in the Sagnac set-up to determine if it was a Fizeau effect, and they >> concluded it was not. Post has written about this. >> Tom Roberts erroneously states that the ballistic model cannot explain >> Sagnac. I will acknowledge that the "re-emission" ballistic model is >> denied by the Sagnac results. Tolman (1912) and Panofsky and Phillips >> (1961) describe three ballistic models. Waldron (1977) describes two >> of the three: the ballistic model of Ritz/Waldron and the re-emission >> model. The re-emission model fails in explaining Sagnac and a host of >> other experiments. >> 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 > >Correct. Very good analysis. One tiny flaw... >Newton's corpuscles of light model, today called photons, predates >Walter Ritz by 250 years. >Of course a FOG cannot in any way be related to Einstein's relativity, >since that specifically states light is always propagated in empty space >with a definite velocity c which is independent of the state of motion >of the emitting body and a FOG isn't empty space. > Hence Andersen's and Roberts' arguments are non sequitur. > >For amusement only: > If the duellists shoot arrows at each other at v feet per second >and the train accelerates at g fps/second, how far apart should >the duellists be to guarantee one of them survives? > Yes also, on FOG not being related to Einstein's special relativity (SRT). There are a number of people in a discussion group that I belong to that insist that Sagnac and Michelson-Gale refute SRT. I cannot get on that bandwagon because the Sagnac phenomenon resides exclusively within accelerated FOR. Very clever puzzle with the arrow scenario� Let us know when you've worked it out.
From: tominlaguna on 17 Oct 2009 04:23 On Fri, 16 Oct 2009 15:35:46 -0400, 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. > >> Saburi in 1976 demonstrated that there was a radio signal >> transit time difference east-west between two earth-stationary >> receiver/transmitters. > >Interesting! Did they measure whether the effect was the same in the >morning and evening? > >While looking for Saburi I found this which may be of some interest: > >http://adsabs.harvard.edu/full/1986IAUS..114..299A 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. 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. 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. I have a copy of the Allan and Ashby paper you linked; unfortunately, I do not have copies of either of Saburi's papers. Later today, Ron Hatch will hold a webinar at NPA to discuss Ashby's relativistic views on GPS and Sagnac. Though I'm not a fan of Ron's Lorentz ether theory, it might be fun to watch him poke a finger in Ashby's eye.
From: Jonah Thomas on 17 Oct 2009 09:33
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. 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? > 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. |