Speed of Light: A universal Constant?
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From: Paul B. Andersen on 18 Apr 2005 10:16 Henri Wilson wrote: > On Thu, 14 Apr 2005 00:30:42 +0100, "George Dishman" <george(a)briar.demon.co.uk> > wrote: > >>"Henri Wilson" <H@..> wrote in message >>news:s03r51d3gmd6qick1ffuuiebr31gljr9lk(a)4ax.com... >>>What I have realised is that the standard SR explanation doesn't work!! >>> >>>FOR A CONSTANT RATE OF ROTATION, THERE WOULD BE NO FRINGE MOVEMENT. >>> >>>The pattern would remain fixed. And that is not what happens, surely. >>>Your version of Sagnac would be sensitive to angular acceleration only. >> >>Why? The animation shows that there is a >>clear time difference produced in the SR >>version. What you say is inconflict with >>what it shows yet you just make that bald >>statement without giving any reason. > > > Think about it George. > For constant rotation (incuding zero), there is a constant relationship between > the two path lengths. The fringes should remain static. > That is not what happens. Of course that's what happens, and of course that's what SR say should happen. The term "fringe shift" refers to the shift of the fringes when the interferometer is rotating compared to when it is not. What did YOU think "fringe shift" meant? That the fringes are moving? They are not in a Sagnac interferometer rotating at a constant rate. Ring lasers are quite different, though. That's why ring lasers rather than Sagnac rings are used in inertial navigational systems. Sagnac rings and ring lasers both falsifies the ballistic theory. Obviously. Paul
From: George Dishman on 18 Apr 2005 16:23 "bz" <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message news:Xns963BC75105485WQAHBGMXSZHVspammote(a)130.39.198.139... > >> On Sun, 17 Apr 2005 01:01:35 +0000 (UTC), bz >> <bz+sp(a)ch100-5.chem.lsu.edu> wrote: .... >>>http://www.fesg.tu-muenchen.de/us/Docs/Ring-SPb04.pdf .... > It seemed to be germain to the discussion. > >>>http://www.phys.canterbury.ac.nz/research/laser/ring_open.shtml Thanks for the pointers. The ring laser is difficult to use in this argument as it isn't obvious how to define the source velocity when it is a laser cavity which is why I highlighted the iFOG version. However, the historical background was interesting and I wasn't aware of the contribution of Larmor and Lodge. George
From: George Dishman on 18 Apr 2005 16:33 "Henri Wilson" <H@..> wrote in message news:gap6615gqhqdk8aafdb7oto1uumiekbfjr(a)4ax.com... > On Sun, 17 Apr 2005 23:50:03 +0100, "George Dishman" > <george(a)briar.demon.co.uk> wrote: >> >>The details will be commercial so not published >>but there are other sources that give generic >>descriptions. I'll try to dig some out when >>I have time but given the specs and some basic >>facts, we can get some good estimates. > > Not only that, much of the theory and design criteria are apparently > highly > secret for defence reasons. So maybe we will never know. Some of the more advanced stuff perhaps but the fundamentals are well known. Probably the only significant refinement is the use of modulation as outlined here: http://www.physik.fu-berlin.de/~bauer/habil_online/node11.html That's the technique KVH use and I have seen a number of other sites discussing it. However, this isn't really too important from the point of view of your animation. George
From: George Dishman on 18 Apr 2005 16:53 "Henri Wilson" <H@..> wrote in message news:sar561ta9rd06mgdj1eo8rgv4edkbfj0pn(a)4ax.com... > > I think we now both agree on the basic problem. The ballistic argument > goes > like this: > > ____________M->v > /\ > / \ > s > > With mirror at rest in the source frame, light is reflected at 45deg from > a > plane mirror. > Q) If the mirror is subsequently moved in the direction indicated, what is > the > effect on the reflected angle and the outgoing velocity, relative to the > source > frame? > In the case of a perfectly elastic ball bouncing off a rigid 'frictionles' > wall, the reflection should not be affected at all by wall movement. > > However, in real situations there will always be some kind of interaction > between the ball and the wall. The normal velocity component should not be > affected but the parallel one will be, as will the apparent angle of > incidence. > > It is possible that the reflected angle may not be the same as the > incident > one. In the extreme case, the ball could leave the wall with a parallel > speed > equal to that of the wall. in fact we cannot really be certain that the > normal > velocity is not also altered in the process. > > Does that sum it up adequately? It is pretty good. What you have said is that you will not rule out changes to both the normal and parallel components. I won't object to that but I would suggest some extra constraints: 1) There are no "tick fairies". That means that wavefronts are conserved, neither created nor destroyed by reflection. 2) The process cannot have a preferred direction of the mirror therefore your formula should be symmetrical about the normal. In other words, the angles should be reversed if I swap the source like this: > ____________M->v > /\ > / \ > s 3) The direction of propagation is normal to the wavefronts. 4) The angle of the wavefront can be determined by Huygens method (this follows from point 1). 5) Your formula should be able to be applied to all reflection phenomena. For example it must apply to long range fibres so must not predict the destruction of a signal at extreme grazing angles. > I will try to incorporate all these possibilities into my simulation. I think if you work out your formula based on the limitations above, it may reduce the number of variables you have to consider and make the work easier. The more that can be done analytically before animating, the better. Rather than cover this ground again some months down the line, I would like to just note that the standard law of reflection together with either of the two simple ballistic models I mentioned both predict no phase shift in the Sagnac setup. We discussed this earlier but never really reached agreement. I think now we have covered many all the areas where you had doubts so do you realise that what I said is correct and that a more complex model for reflection is necessary if ballistic theory is to give a non-null prediction? George
From: Henri Wilson on 18 Apr 2005 18:09
On Mon, 18 Apr 2005 21:33:08 +0100, "George Dishman" <george(a)briar.demon.co.uk> wrote: > >"Henri Wilson" <H@..> wrote in message >news:gap6615gqhqdk8aafdb7oto1uumiekbfjr(a)4ax.com... >> On Sun, 17 Apr 2005 23:50:03 +0100, "George Dishman" >> <george(a)briar.demon.co.uk> wrote: >>> >>>The details will be commercial so not published >>>but there are other sources that give generic >>>descriptions. I'll try to dig some out when >>>I have time but given the specs and some basic >>>facts, we can get some good estimates. >> >> Not only that, much of the theory and design criteria are apparently >> highly >> secret for defence reasons. So maybe we will never know. > >Some of the more advanced stuff perhaps but the >fundamentals are well known. Probably the only >significant refinement is the use of modulation >as outlined here: > >http://www.physik.fu-berlin.de/~bauer/habil_online/node11.html I assume the modulating increases the sensitivity. > >That's the technique KVH use and I have seen a >number of other sites discussing it. However, >this isn't really too important from the point >of view of your animation. One of my main concerns is that in steady rotation, there can be no change in the output pattern, whatever that may be. So to obtain a reading for actual rotation from the starting zero, a continuous integration must be carried out. That applies to my ballistic concept as well as your standard treatment. > >George > HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong. |