Wang / Sagnac Devices
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From: Inertial on 26 Oct 2009 22:21 "Jonah Thomas" <jethomas5(a)gmail.com> wrote in message news:20091026211828.4308ecd3.jethomas5(a)gmail.com... > Darwin123 <drosen0000(a)yahoo.com> wrote: > >> I found a link. It appears that there are two ways of measuring >> "the" Sagnac effect: one with fringe position and one with time. Here >> is a link. >> http://www.cleonis.nl/physics/phys256/sagnac.php > > Thank you! I had seen that page but hadn't given it the attention it > deserved. All it is is a copy/paste of the wikipedia page on the Sagnac effect >> The following are my selections from this link. I notice that >> there are two types of detectors described. In one configuration the >> experimenter measures spatial fringe shift, and in the other the >> experimenter measures temporal beats. The supposed observer in the >> inertial frame is supposed to be measuring differences in wavelength >> for the fringe shift, and differences in frequency for the temporal >> beats. > > So any theory about Sagnac should predict both effects. Theories with > constant lightspeed will inevitably predict both effects. Only one of those is Sagnac. There are no frequency beats in Sagnac because there is no difference in frequency. Though similar looking in a diagram there are other issues afoot in the ring gyro.
From: Tom Roberts on 26 Oct 2009 23:38 Jonah Thomas wrote: > I'll say it again: One beam of light leaves the emitter at speed c > relative to the emitter. It goes through a beam-splitter which does not > change its speed. It bounces off mirrors which do not change its speed. > So the light traveling in opposite directions travel at the same speed. [I assume you are still trying to discuss some sort of ballistic or emission theory.] The only frame in which this could possibly be true is the rotating frame. But in that frame you don't know how things like beam splitters and mirrors behave. You are ASSUMING that they behave in the rotating frame just like they do in an inertial frame, and that's just plain wrong -- they CANNOT possibly do that and still behave correctly in an inertial frame. As I have said before, you are being TOO IMPRECISE in your descriptions. You are not specifying in which frame you description holds, and thus end up with nonsense. You are not specifying your model, either, making it impossible for others to interpret your words or figure out what you are tying to say. Do not expect people to figure it out from context, because that is muddled; mention both frame and model explicitly, each and every time. You fool yourself by attempting to analyze in the rotating frame. It is straightforward to analyze the Sagnac interferometer in the inertial frame of its center. Consider any emission or ballistic theory that satisfies: A) light is emitted with speed c relative to the instantaneously- comoving inertial frame of its source B) Snell's law holds for a mirror in its instantaneously-comoving inertial frame, and the reflected light has the same speed as the incoming light in this frame C) a beam splitter emits light from both outputs with the same speed the incoming light had in the instantaneously-comoving inertial frame of the splitter D) Galilean relativity holds for light Do the analysis for a short light pulse, and you'll find that any such theory predicts the two halves of the split light pulse arrive at the detector simultaneously via the two counter-propagating paths. That implies no fringe shift, so any such theory is refuted. Tom Roberts
From: Jonah Thomas on 27 Oct 2009 01:02 "Inertial" <relatively(a)rest.com> wrote: > "Jonah Thomas" <jethomas5(a)gmail.com> wrote > > Darwin123 <drosen0000(a)yahoo.com> wrote: > > > >> I found a link. It appears that there are two ways of measuring > >> "the" Sagnac effect: one with fringe position and one with time. > >Here> is a link. > >> http://www.cleonis.nl/physics/phys256/sagnac.php > > > > Thank you! I had seen that page but hadn't given it the attention it > > deserved. > > All it is is a copy/paste of the wikipedia page on the Sagnac effect That's likely where I saw it. > >> The following are my selections from this link. I notice that > >> there are two types of detectors described. In one configuration > >the> experimenter measures spatial fringe shift, and in the other the > >> experimenter measures temporal beats. The supposed observer in the > >> inertial frame is supposed to be measuring differences in > >wavelength> for the fringe shift, and differences in frequency for > >the temporal> beats. > > > > So any theory about Sagnac should predict both effects. Theories > > with constant lightspeed will inevitably predict both effects. > > Only one of those is Sagnac. There are no frequency beats in Sagnac > because there is no difference in frequency. Though similar looking > in a diagram there are other issues afoot in the ring gyro. Oh? So Sagnac, ring gyros, and Wang are all different? I haven't seen an argument yet why there shouldn't be frequency differences in Sagnac. There is a theory predicting the result that uses only speed differences, and if that theory is correct then frequency differences would contaminate the data. Do you know whether anyone has tested for frequency differences in Sagnac?
From: Jonah Thomas on 27 Oct 2009 01:08 Tom Roberts <tjroberts137(a)sbcglobal.net> wrote: > Jonah Thomas wrote: > > I'll say it again: One beam of light leaves the emitter at speed c > > relative to the emitter. It goes through a beam-splitter which does > > not change its speed. It bounces off mirrors which do not change its > > speed. So the light traveling in opposite directions travel at the > > same speed. > > [I assume you are still trying to discuss some sort of > ballistic or emission theory.] > > The only frame in which this could possibly be true is the rotating > frame. But in that frame you don't know how things like beam splitters > > and mirrors behave. You are ASSUMING that they behave in the rotating > frame just like they do in an inertial frame, and that's just plain > wrong -- they CANNOT possibly do that and still behave correctly in an > > inertial frame. > > As I have said before, you are being TOO IMPRECISE in your > descriptions. Thank you. I'll try to write more precisely. > You are not specifying in which frame you description holds, and thus > end up with nonsense. You are not specifying your model, either, > making it impossible for others to interpret your words or figure out > what you are tying to say. Do not expect people to figure it out from > context, because that is muddled; mention both frame and model > explicitly, each and every time. > > You fool yourself by attempting to analyze in the rotating frame. It > is straightforward to analyze the Sagnac interferometer in the > inertial frame of its center. I wasn't trying to analyze in the rotating frame. I think you thought that because you knew that in an inertial frame what I wanted to do isn't possible. But I didn't know that it isn't possible. Consider any emission or ballistic theory that > satisfies: > A) light is emitted with speed c relative to the instantaneously- > comoving inertial frame of its source > B) Snell's law holds for a mirror in its instantaneously-comoving > inertial frame, and the reflected light has the same speed as > the incoming light in this frame > C) a beam splitter emits light from both outputs with the same > speed the incoming light had in the instantaneously-comoving > inertial frame of the splitter > D) Galilean relativity holds for light > > Do the analysis for a short light pulse, and you'll find that any such > > theory predicts the two halves of the split light pulse arrive at the > detector simultaneously via the two counter-propagating paths. That > implies no fringe shift, so any such theory is refuted. I agree with you about those conditions. I want to find alternatives for your B and C, but it may not be possible.
From: Inertial on 27 Oct 2009 01:47
"Jonah Thomas" <jethomas5(a)gmail.com> wrote in message news:20091027010804.1b76c159.jethomas5(a)gmail.com... > Tom Roberts <tjroberts137(a)sbcglobal.net> wrote: >> Jonah Thomas wrote: > >> > I'll say it again: One beam of light leaves the emitter at speed c >> > relative to the emitter. It goes through a beam-splitter which does >> > not change its speed. It bounces off mirrors which do not change its >> > speed. So the light traveling in opposite directions travel at the >> > same speed. >> >> [I assume you are still trying to discuss some sort of >> ballistic or emission theory.] >> >> The only frame in which this could possibly be true is the rotating >> frame. But in that frame you don't know how things like beam splitters >> >> and mirrors behave. You are ASSUMING that they behave in the rotating >> frame just like they do in an inertial frame, and that's just plain >> wrong -- they CANNOT possibly do that and still behave correctly in an >> >> inertial frame. >> >> As I have said before, you are being TOO IMPRECISE in your >> descriptions. > > Thank you. I'll try to write more precisely. > >> You are not specifying in which frame you description holds, and thus >> end up with nonsense. You are not specifying your model, either, >> making it impossible for others to interpret your words or figure out >> what you are tying to say. Do not expect people to figure it out from >> context, because that is muddled; mention both frame and model >> explicitly, each and every time. >> >> You fool yourself by attempting to analyze in the rotating frame. It >> is straightforward to analyze the Sagnac interferometer in the >> inertial frame of its center. > > I wasn't trying to analyze in the rotating frame. I think you thought > that because you knew that in an inertial frame what I wanted to do > isn't possible. But I didn't know that it isn't possible. > > Consider any emission or ballistic theory that >> satisfies: >> A) light is emitted with speed c relative to the instantaneously- >> comoving inertial frame of its source >> B) Snell's law holds for a mirror in its instantaneously-comoving >> inertial frame, and the reflected light has the same speed as >> the incoming light in this frame >> C) a beam splitter emits light from both outputs with the same >> speed the incoming light had in the instantaneously-comoving >> inertial frame of the splitter >> D) Galilean relativity holds for light >> >> Do the analysis for a short light pulse, and you'll find that any such >> >> theory predicts the two halves of the split light pulse arrive at the >> detector simultaneously via the two counter-propagating paths. That >> implies no fringe shift, so any such theory is refuted. > > I agree with you about those conditions. I want to find alternatives for > your B and C, but it may not be possible. Why do you *want* to find alternatives? |