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Mar 7, 2000, 3:00:00 AM3/7/00

to

Sagnac & relativity

In this group I recently found statements to the effect that the Sagnac

experiment was explained and even predicted (sic!) by SR. I have perused

many books on relativity dating back to 1920, including Einstein's, and saw

no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

magnetism and relativity ('55?), where a GR explanation of it was

presented.

I have the following questions to relativity fans:

1. Do you agree, that, if two waves radiated at the same point return to

that point with an accumulated phase difference, this means that there is a

difference in either their:

a) paths, or

b) phase velocities?

Or, perhaps, you can suggest another possibility?

2. When, as in Sagnac experiment, two waves are made to travel in opposite

directions along the same path (typically, an optical filament), does this

path in some mysterious way become, in the course of the ring's rotation,

different for the clock-wise and the anti-clockwise waves?

3. If not, how, with the phase velocity being equal for both waves, can a

phase difference accumulate?

Thanks for the answers.

Mar 7, 2000, 3:00:00 AM3/7/00

to

MS: >2. When, as in Sagnac experiment, two waves are made to travel in opposite

>directions along the same path (typically, an optical filament), does this

>path in some mysterious way become, in the course of the ring's rotation,

>different for the clock-wise and the anti-clockwise waves?

>directions along the same path (typically, an optical filament), does this

>path in some mysterious way become, in the course of the ring's rotation,

>different for the clock-wise and the anti-clockwise waves?

Dennis: You may not believe this, but that is precisely the relativist

argument. Heck, people accepted the Copenhagen interpretation for decades, why

not that a path is longer clockwise than counter-clockwise? There is simply no

limit or boundary to what people are willing to believe in defense of certain

theories.

Dennis McCarthy

Mar 7, 2000, 3:00:00 AM3/7/00

to

In article <8a30d6$2j19$1...@gavrilo.mtu.ru>, "Mark Samokhvalov"

<samokh...@mtu-net.ru> wrote:

<samokh...@mtu-net.ru> wrote:

> Sagnac & relativity

>

> In this group I recently found statements to the effect that the Sagnac

> experiment was explained and even predicted (sic!) by SR. I have perused

> many books on relativity dating back to 1920, including Einstein's, and saw

> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

> magnetism and relativity ('55?), where a GR explanation of it was

> presented.

> I have the following questions to relativity fans:

> 1. Do you agree, that, if two waves radiated at the same point return to

> that point with an accumulated phase difference, this means that there is a

> difference in either their:

> a) paths, or

> b) phase velocities?

> Or, perhaps, you can suggest another possibility?

> 2. When, as in Sagnac experiment, two waves are made to travel in opposite

> directions along the same path (typically, an optical filament), does this

> path in some mysterious way become, in the course of the ring's rotation,

> different for the clock-wise and the anti-clockwise waves?

If you look at the path in an inertial frame (in which the speed of

light going round the ring is c) it's clear that, as the ring is rotating,

a light beam travelling in the direction of rotating has to travel further

than one travelling against the direction of rotation in order to return

to the point on the ring from which they were emitted. I would not

describe that as 'mysterious' but rather as 'obvious'.

--

Felix qui potuit rerum cognoscere causas - Virgil.

Mar 7, 2000, 3:00:00 AM3/7/00

to

Mark Samokhvalov wrote:

> Sagnac & relativity

>

> In this group I recently found statements to the effect that the

> Sagnac experiment was explained and even predicted (sic!) by SR. I

> have perused many books on relativity dating back to 1920, including

> Einstein's, and saw no mention of Sagnac, until I came across a

> textbook by M.-A.Tonnella on magnetism and relativity ('55?), where

> a GR explanation of it was presented.

> I have the following questions to relativity fans:

> 1. Do you agree, that, if two waves radiated at the same point return

> to that point with an accumulated phase difference, this means that

> there is a difference in either their:

> a) paths, or

> b) phase velocities?

> Or, perhaps, you can suggest another possibility?

> 2. When, as in Sagnac experiment, two waves are made to travel in

> opposite directions along the same path (typically, an optical

> filament), does this path in some mysterious way become, in the

> course of the ring's rotation, different for the clock-wise and

> the anti-clockwise waves?

> 3. If not, how, with the phase velocity being equal for both waves,

> can a phase difference accumulate?

> Thanks for the answers.

SR predicts the Sagnac effect quite easily, and here's a beautiful

derivation and explanation:

http://mathpages.com/rr/s2-07/2-07.htm

1a) yes, different path lengths

2) no mystery needed, a rotating frame is non-inertial

---Tim Shuba---

Sent via Deja.com http://www.deja.com/

Before you buy.

Mar 7, 2000, 3:00:00 AM3/7/00

to

Dennis McSophist wrote:

> > When, as in Sagnac experiment, two waves are made to travel in

> > opposite directions along the same path (typically, an optical

> > filament), does this path in some mysterious way become, in the

> > course of the ring's rotation, different for the clock-wise and

> > the anti-clockwise waves?

>

> Dennis: You may not believe this, but that is precisely the

> relativist argument. Heck, people accepted the Copenhagen

> interpretation for decades, why not that a path is longer

> clockwise than counter-clockwise? There is simply no

> limit or boundary to what people are willing to believe

> in defense of certain theories.

No limit? Yes indeed Mr Sophist. How many dozens of posts have

you made about Sagnac? SR's explanation is simple and consistent.

See http://mathpages.com/rr/s2-07/2-07.htm for an explanation

that includes the exact reason why the Sagnac effect is perfect

fodder for your sophistry. Note especially the last paragraph.

Mar 7, 2000, 3:00:00 AM3/7/00

to

Dennis: Unfortunately, here's the problem:

"Still, the doubter imagines that we can transform this bias away, by treating

the situation with respect to coordinates that are rigidly attached to and

rotating along with the device. Surely (he reasons) we can regard the paths of

the two light beams as spatially congruent and equal as seen from this system

of reference, and so the asymmetric travel times must imply anisotropic light

speed with respect to these coordinates. This is actually true, in the sense

that it's possible to define a system of coordinates in terms of which the

positions of the points on the disk are independent of the time coordinate, but

of course such coordinates are necessarily accelerating (viz., rotating), and

special relativity does not assume light speed to be isotropic with respect to

non-inertial coordinates."

That's called the "naive" SR explanation. Allowing anisotropy wrt the

non-inertial rim observer results in the Selleri paradox.

If you want the correct SR explanation, check Rizzi and Tartaglia's.

You'll find it's not so simple. And you'll find that the explanation does in

fact involve that " this path in some mysterious way become, in the course of

the ring's rotation, different for the clock-wise and

the anti-clockwise waves"--even for the rim observer.

Dennis McCarthy

Mar 7, 2000, 3:00:00 AM3/7/00

to

><samokh...@mtu-net.ru> wrote:

>

>> Sagnac & relativity

>>

>> In this group I recently found statements to the effect that the Sagnac

>> experiment was explained and even predicted (sic!) by SR. I have perused

>> many books on relativity dating back to 1920, including Einstein's, and saw

>> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

>> magnetism and relativity ('55?), where a GR explanation of it was

>> presented.

>> I have the following questions to relativity fans:

>> 1. Do you agree, that, if two waves radiated at the same point return to

>> that point with an accumulated phase difference, this means that there is a

>> difference in either their:

>> a) paths, or

>> b) phase velocities?

>> Or, perhaps, you can suggest another possibility?

>> 2. When, as in Sagnac experiment, two waves are made to travel in opposite>

>> Sagnac & relativity

>>

>> In this group I recently found statements to the effect that the Sagnac

>> experiment was explained and even predicted (sic!) by SR. I have perused

>> many books on relativity dating back to 1920, including Einstein's, and saw

>> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

>> magnetism and relativity ('55?), where a GR explanation of it was

>> presented.

>> I have the following questions to relativity fans:

>> 1. Do you agree, that, if two waves radiated at the same point return to

>> that point with an accumulated phase difference, this means that there is a

>> difference in either their:

>> a) paths, or

>> b) phase velocities?

>> Or, perhaps, you can suggest another possibility?

>> directions along the same path (typically, an optical filament), does this

>> path in some mysterious way become, in the course of the ring's rotation,

>> different for the clock-wise and the anti-clockwise waves?

>

>light going round the ring is c) it's clear that, as the ring is rotating,

>a light beam travelling in the direction of rotating has to travel further

>than one travelling against the direction of rotation in order to return

>to the point on the ring from which they were emitted. I would not

>describe that as 'mysterious' but rather as 'obvious'.

Dennis: Ahh, so you think it is "obvious" that when you move at a light beam,

it approaches you faster than when you move away from it?

I agree that that is obvious, but you wouldn't believe that some people try to

deny it.

Dennis McCarthy

Mar 7, 2000, 3:00:00 AM3/7/00

to

>SR predicts the Sagnac effect quite easily, and here's a beautiful

>derivation and explanation:

>

>http://mathpages.com/rr/s2-07/2-07.htm

>

>1a) yes, different path lengths

>

>2) no mystery needed, a rotating frame is non-inertial

>derivation and explanation:

>

>http://mathpages.com/rr/s2-07/2-07.htm

>

>1a) yes, different path lengths

>

>2) no mystery needed, a rotating frame is non-inertial

D: Sorry. 1) The path lengths aren't different to a person on the rim.

2) The non-inertial fall back has been rejected by mainstream physicists.

Check Rizzi and Tartaglia's explanation for the correct SR version.

Dennis McCarthy

Mar 7, 2000, 3:00:00 AM3/7/00

to

In <stephenwells-0...@mac009.joh.cam.ac.uk>

> If you look at the path in an inertial frame (in which the speed of

>light going round the ring is c) it's clear that, as the ring is

rotating,

>a light beam travelling in the direction of rotating has to travel

further

>than one travelling against the direction of rotation in order to

return

>to the point on the ring from which they were emitted. I would not

>describe that as 'mysterious' but rather as 'obvious'.

>light going round the ring is c) it's clear that, as the ring is

rotating,

>a light beam travelling in the direction of rotating has to travel

further

>than one travelling against the direction of rotation in order to

return

>to the point on the ring from which they were emitted. I would not

>describe that as 'mysterious' but rather as 'obvious'.

Geez, we agree. What a shocker...

Paul Stowe

Mar 7, 2000, 3:00:00 AM3/7/00

to

Mark Samokhvalov wrote:

> Sagnac & relativity

>

> In this group I recently found statements to the effect that the Sagnac

> experiment was explained and even predicted (sic!) by SR. I have perused

> many books on relativity dating back to 1920, including Einstein's, and saw

> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

> magnetism and relativity ('55?), where a GR explanation of it was

> presented.

> I have the following questions to relativity fans:

> 1. Do you agree, that, if two waves radiated at the same point return to

> that point with an accumulated phase difference, this means that there is a

> difference in either their:

> a) paths, or

> b) phase velocities?

> Or, perhaps, you can suggest another possibility?

It could be their frequencies which differ.

> 2. When, as in Sagnac experiment, two waves are made to travel in opposite

> directions along the same path (typically, an optical filament), does this

> path in some mysterious way become, in the course of the ring's rotation,

> different for the clock-wise and the anti-clockwise waves?

> 3. If not, how, with the phase velocity being equal for both waves, can a

> phase difference accumulate?

What makes you think that the phase velocity is equal for the two waves?

You're not in an inertial frame...

Mar 7, 2000, 3:00:00 AM3/7/00

to

Mark Samokhvalov wrote:

> In this group I recently found statements to the effect that the Sagnac

> experiment was explained and even predicted (sic!) by SR.

> In this group I recently found statements to the effect that the Sagnac

> experiment was explained and even predicted (sic!) by SR.

It is easily explained by SR. I do not think it was predicted by

any SR advocate before Sagnac performed his experiment (but I am

not an expert on such historical questions).

> 1. Do you agree, that, if two waves radiated at the same point return to

> that point with an accumulated phase difference, this means that there is a

> difference in either their:

> a) paths, or

> b) phase velocities?

> Or, perhaps, you can suggest another possibility?

There could be a difference in the gravitational potential

integrated along their paths. There could be different optical

media in their paths, or media moving differently (but are these

differences in path?). There are probably other possibilities....

> 2. When, as in Sagnac experiment, two waves are made to travel in opposite

> directions along the same path (typically, an optical filament), does this

> path in some mysterious way become, in the course of the ring's rotation,

> different for the clock-wise and the anti-clockwise waves?

This depends upon what coordinates (aka reference frame) you use to

describe it. Note that both speed and spatial path length are

inherently coordinate dependent.

Let me assume the center of rotation of the ring interferometer is

at rest in an inertial frame. In this frame SR predicts the speed

of light is isotropically c; in this frame it is clear that the

co-rotating and counter-rotating light rays travel different

distances. So there is no mystery -- the light rays travel

different distances at the same speed and therefore accumulate a

phase difference.

One might also describe this in coordinates rotating with the

ring interferometer. In these coordinates the _average_ speed

of light _going_all_the_way_around_the_ring_ is different for

the two directions, but the distance is the same for both rays.

Again there is no mystery -- the light rays travel the same

distance at different average speeds and therefore accumulate

a phase difference.

Note that it is tricky to define "speed of light"

in these coordinates, but there is indeed a well-defined

_average_ speed of light _going_all_the_way_around_.

This is intimitely related to the difficulty of

synchronizing clocks in a rotating system....

One could also describe this in the inertial frame which is

co-moving with the emitter/detector when the rays are emitted

(think of very short pulses of light). Note that the emitter/

detector moves (slightly) in this frame while the rays are in

transit. In this frame the speed of light is isotropically c,

and the two paths the rays follow are distorted circles which

are not congruent, and which have different lengths. Again

there is no mystery -- the light rays travel different

distances at the same speed and therefore accumulate a phase

difference.

One could also choose any other inertial frame. Again the

conclusion is that the light rays travel different distances

at the same speed and therefore accumulate a phase difference.

> 3. If not, how, with the phase velocity being equal for both waves, can a

> phase difference accumulate?

See above. Like so many things, one can consider it in several

different ways, and one's description/explanation will be

different for different viewpoints. And as always, one must

use a single viewpoint (coordinate system) for the entire

analysis.

This latter seems to be the problem in your question, in

which you appear to switch between the co-rotating frame

and an inertial frame. You seem to (implicitly) think

that SR implies that the speed of light in the rotating

system will be isotropically c -- that is _NOT_ true.

Your "same path" is true only in the rotating system,

and you clearly mean same _spatial_ path (in spacetime

there is no way to consider the two rays as following

the same path -- they are helices of opposite twist

and different path length).

Tom Roberts tjro...@lucent.com

Mar 8, 2000, 3:00:00 AM3/8/00

to

On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>>See http://mathpages.com/rr/s2-07/2-07.htm for an explanation

>>that includes the exact reason why the Sagnac effect is perfect

>>fodder for your sophistry. Note especially the last paragraph.

>Dennis: Unfortunately, here's the problem:

>

>"Still, the doubter imagines... isotropic with respect to>>See http://mathpages.com/rr/s2-07/2-07.htm for an explanation

>>that includes the exact reason why the Sagnac effect is perfect

>>fodder for your sophistry. Note especially the last paragraph.

>Dennis: Unfortunately, here's the problem:

>

>non-inertial coordinates."

>

>That's called the "naive" SR explanation...

As usual, Dennis is quite wrong about this. I checked the referenced

web page, and the very next paragraph after the one Dennis quotes says

"There are, however, some interesting issues raised by

accelerating coordinate systems, but we'll defer discussion

of those until Section 4.5. For the moment, let's just confine

our attention to inertial coordinates, and show how a Sagnac

device appears in terms of the co-moving inertial frame of

an arbitrary point on the perimeter."

It then goes on to describe the Sagnac effect for a range of inertial

coordinates, and then in Section 4.5 discusses the same thing with

respect to accelerated (rotating) coordinates.

On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

> Allowing anisotropy wrt the non-inertial rim observer results

> in the Selleri paradox.

Just so no one is misled by this, Dennis is referring to a silly

mistake by Selleri that was thoroughly debunked in this newsgroup

a year or two ago. Check deja news. In summary, the Sagnac effect

remains proportional to the amount of ANGULAR travel, i.e., rotation,

during the transit of the light, even in the limit as the radius R

of the device goes to infinity.

On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>If you want the correct SR explanation, check Rizzi and Tartaglia's.

>You'll find it's not so simple.

In terms of accelerating coordinates, very few physical phenomena

can be described simply - which is why we seldom use accelerating

coordinates when we can avoid it (as we certainly can in this case).

The explanation given by Rizzi and Tartaglia for accelerating

coordinates is similar to the explanation given in Section 4.5

of the web page referenced above.

>And you'll find that the explanation does in fact involve that

>"this path in some mysterious way becomes, in the course of

>the ring's rotation, different for the clock-wise and the

>anti-clockwise waves"--even for the rim observer.

Again, just so no one is misled, Dennis is completely incorrect in

his assessment. There is nothing mysterious about accelerating

coordinate systems, at least not to anyone who understands them.

Mar 8, 2000, 3:00:00 AM3/8/00

to

Tom Roberts пишет в сообщении <38C5C242...@chicago.avenew.com> ...

>Mark Samokhvalov wrote:

>> In this group I recently found statements to the effect that the Sagnac

>> experiment was explained and even predicted (sic!) by SR.

>

>It is easily explained by SR. I do not think it was predicted by

>any SR advocate before Sagnac performed his experiment (but I am

>not an expert on such historical questions).

>

>

>> 1. Do you agree, that, if two waves radiated at the same point return to

>> that point with an accumulated phase difference, this means that there is

a

>> difference in either their:

>> a) paths, or

>> b) phase velocities?

>> Or, perhaps, you can suggest another possibility?

>

>There could be a difference in the gravitational potential

>integrated along their paths. There could be different optical

>media in their paths, or media moving differently (but are these

>differences in path?).

Yes, they are differences in optical paths.

>There are probably other possibilities..

Are there?

.

>

>

>> 2. When, as in Sagnac experiment, two waves are made to travel in

opposite

>> directions along the same path (typically, an optical filament), does

this

>> path in some mysterious way become, in the course of the ring's rotation,

>> different for the clock-wise and the anti-clockwise waves?

>

>This depends upon what coordinates (aka reference frame) you use to

>describe it. Note that both speed and spatial path length are

>inherently coordinate dependent.

That was my slip. I thought, those informed knew, the problem existed only

in the rotating RF. In a RF at rest wrt ether, SR = LET.

>

>Let me assume the center of rotation of the ring interferometer is

>at rest in an inertial frame. In this frame SR predicts the speed

>of light is isotropically c; in this frame it is clear that the

>co-rotating and counter-rotating light rays travel different

>distances. So there is no mystery -- the light rays travel

>different distances at the same speed and therefore accumulate a

>phase difference.

Exactly. Here SR = LET.

>One might also describe this in coordinates rotating with the

>ring interferometer. In these coordinates the _average_ speed

>of light _going_all_the_way_around_the_ring_ is different for

>the two directions, but the distance is the same for both rays.

>Again there is no mystery -- the light rays travel the same

>distance at different average speeds and therefore accumulate

>a phase difference.

You are a poor relativist: GR insists: in ALL RF the locally measured

velocity of light is isotropic and = c.

>

> Note that it is tricky to define "speed of light"

> in these coordinates, but there is indeed a well-defined

> _average_ speed of light _going_all_the_way_around_.

> This is intimitely related to the difficulty of

> synchronizing clocks in a rotating system....

There's no such problem in this case with the point of emission coinciding

with the point of reception.

The whole story reminds me of a Russian anecdote: Contributions were invited

to a conference on new methods in surgery, and one was submitted by an

Armenian team entitled "A New Method of Tonsilectomy". "Could anything be

new in that traditional method?" - "Ah, but you don't know, how we perform

it - we do it thtough the ass hole!" (Armenians in Russia are believed to

have homosexual preferemces.)

Mar 8, 2000, 3:00:00 AM3/8/00

to

Dennis McCarthy <djm...@aol.com> wrote in message

news:20000307180426...@ng-cb1.aol.com...

> >SR predicts the Sagnac effect quite easily, and here's a beautiful

> >derivation and explanation:

> >

> >http://mathpages.com/rr/s2-07/2-07.htm

> >

> >1a) yes, different path lengths

> >

> >2) no mystery needed, a rotating frame is non-inertial

>

> D: Sorry. 1) The path lengths aren't different to a person on the rim.

The previous poster was referring to the inertial lab system.

> 2) The non-inertial fall back has been rejected by mainstream physicists.

Nonsense.

> Check Rizzi and Tartaglia's explanation for the correct SR version.

They didn't investigate the matter fully because their main concern

was Selleri's paradox. In fact noninertial frames work here just fine.

Mar 8, 2000, 3:00:00 AM3/8/00

to

Mark Samokhvalov wrote:

>

> Sagnac & relativity

>

>

> Sagnac & relativity

>

> In this group I recently found statements to the effect that the Sagnac

> experiment was explained and even predicted (sic!) by SR. I have perused

> many books on relativity dating back to 1920, including Einstein's, and saw

> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

> magnetism and relativity ('55?), where a GR explanation of it was

> presented.

> many books on relativity dating back to 1920, including Einstein's, and saw

> no mention of Sagnac, until I came across a textbook by M.-A.Tonnella on

> magnetism and relativity ('55?), where a GR explanation of it was

> presented.

A very good reference which analyzes many aspects of the problem,

considering relativistic as well as non-relativistic Sagnac, is [1]. A

pedagogical treatment can also be found in [2] for light Sagnac. A

presentation of the experiments based on light can be found in [3]. For

the experiments using neutrons, see [5].

> I have the following questions to relativity fans:

> 1. Do you agree, that, if two waves radiated at the same point return to

> that point with an accumulated phase difference, this means that there is a

> difference in either their:

> a) paths, or

> b) phase velocities?

> Or, perhaps, you can suggest another possibility?

> 2. When, as in Sagnac experiment, two waves are made to travel in opposite

> directions along the same path (typically, an optical filament), does this

> path in some mysterious way become, in the course of the ring's rotation,

> different for the clock-wise and the anti-clockwise waves?

> 3. If not, how, with the phase velocity being equal for both waves, can a

> phase difference accumulate?

As many people, you consider that defining the length of co- and

counter-rotating light rays or the length of the rim itself is a trivial

question. It is not the case at all. Indeed the naive notion of length

require your being able to consider the whole rim or the whole rays at a

given instant. But it can be proved that it is impossible to realize

coherently such a "space + time splitting" because it is impossible to

devise an unambiguous global synchronisation procedure on the whole

ring. I will not give this demonstration because it is too complicated

to expose it in ASCII. The interesting reader is refered to [4] and

references therein.

However, just to give you a flavour of the issue, let's consider the

following a priori straightforward situation: two particles are sent

from some point A on the rim, in opposite directions, with the *same

speed V with respect to the rim*. According to a clock at A, SR predicts

that they do not come back at the same time ! This time delay T between

the two arrivals (which does not depend on V) is observed experimentally

in neutron experiments as a phase shift [5] between the wave functions

of these particles (the experimental configuration is not exactly the

one I described but it is close enough for my example to be relevant).

Now consider two slow moving clocks C+ and C-, respectively co- and

counter-rotating. If they are synchronized with a clock at point A, when

they come back to A, C+ and C- are respectively late and ahead with

respect to A and the difference between their reading is exactly the

above time delay T.

This shows clearly that there is much more than a speed anisotropy at

work in Sagnac experiments, even if an etherist might believe at first

that it is a possible explanation for Sagnac experiments based on light

propagation.

[1] J. Anandan, Phys. Rev. D, Vol. 24, N. 2, (1981) 338

[2] G. Rizzi, A. Tartaglia, gr-qc/9805089

[3] E.J. Post, Rev. Mod. Phys., Vol. 39, N. 2 (1967) 475

[4] V. Cantoni, Il Nuovo Cimento, Vol. 57 B, N. 1 (1968) 220

[5] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

--

Luc Bourhis

Center for Particle Theory

University of Durham, UK

Mar 8, 2000, 3:00:00 AM3/8/00

to

>

>On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>>>See http://mathpages.com/rr/s2-07/2-07.htm for an explanation

>>>that includes the exact reason why the Sagnac effect is perfect

>>>fodder for your sophistry. Note especially the last paragraph.

>>Dennis: Unfortunately, here's the problem:

>>

>>"Still, the doubter imagines... isotropic with respect to

>>non-inertial coordinates."

>>

>>That's called the "naive" SR explanation...

>

Rchan: >As usual, Dennis is quite wrong about this. >On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>>>See http://mathpages.com/rr/s2-07/2-07.htm for an explanation

>>>that includes the exact reason why the Sagnac effect is perfect

>>>fodder for your sophistry. Note especially the last paragraph.

>>Dennis: Unfortunately, here's the problem:

>>

>>"Still, the doubter imagines... isotropic with respect to

>>non-inertial coordinates."

>>

>>That's called the "naive" SR explanation...

>

Dennis: Hmmm. First post to me and already sets the tone. Couldn't you have

been more polite?

Rchan: I checked the referenced

>web page, and the very next paragraph after the one Dennis quotes says

>

> "There are, however, some interesting issues raised by

> accelerating coordinate systems, but we'll defer discussion

> of those until Section 4.5. For the moment, let's just confine

> our attention to inertial coordinates,

Dennis: That paragraph I quoted does not confine its "attention to inertial

coordinates." Instead, it states "but

of course such coordinates are necessarily accelerating (viz., rotating), and

special relativity does not assume light speed to be isotropic with respect to

non-inertial coordinates."

Are you arguing that it is theoretically acceptable for the SR explanation to

assume that the speed of light is non-isotropic for the rim observer?

>On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>> Allowing anisotropy wrt the non-inertial rim observer results

>> in the Selleri paradox.

>

Rchan: >Just so no one is misled by this, Dennis is referring to a silly

>mistake by Selleri that was thoroughly debunked in this newsgroup

>a year or two ago.

Dennis: Um, the only "mistake" of Selleri that was *alleged* by R&T was that

the paradox negates the SR view. However, R&T use the Selleri Paradox to

actually *refute* the naive SR position which states that the velocity of light

is anisotropic wrt the rim observer. Instead, they retrieve an explanation for

SR by *avoiding* the Selleri Paradox.

>On 07 Mar 2000 23:01:21 GMT, djm...@aol.com (Dennis McCarthy) wrote:

>>If you want the correct SR explanation, check Rizzi and Tartaglia's.

>>You'll find it's not so simple.

>

>In terms of accelerating coordinates, very few physical phenomena

>can be described simply

Dennis: Sagnac and Michelson did it in a few lines of algebra. According to

the rim observer, the speed of light is c+/-v. Not too hard.

D:>>And you'll find that the explanation does in fact involve that

>>"this path in some mysterious way becomes, in the course of

>>the ring's rotation, different for the clock-wise and the

>>anti-clockwise waves"--even for the rim observer.

>

Rchan: >Again, just so no one is misled, Dennis is completely incorrect in

>his assessment. There is nothing mysterious about accelerating

>coordinate systems, at least not to anyone who understands them.

Dennis: Are you trying to argue that R&T's position regarding the Sagnac effect

was *not* that the "path becomes, in the course of the ring's rotation,

different for the clock-wise and the

anti-clockwise waves"--even for the rim observer?

Dennis McCarthy

Mar 8, 2000, 3:00:00 AM3/8/00

to

>> 2) The non-inertial fall back has been rejected by mainstream physicists.

>

JBiel: >Nonsense.>

Dennis: Well, you know yourself that R&T do argue that the notion that the

speed of light is anisotropic wrt a rim observer is a problem for SR.

>> Check Rizzi and Tartaglia's explanation for the correct SR version.

>

JB: >They didn't investigate the matter fully because their main concern

>was Selleri's paradox. In fact noninertial frames work here just fine.

Dennis: R&T figured it out for the rim observer, i.e., a non-inertial frame.

And you are right that such frames "work just fine"--if you manage to deduce

the fact that the length of the path is different clockwise than

counter-clockwise wrt a rim observer. To me, that seems somewhat artificial.

I would rather trust the rulers of the rim observer, wouldn't you?

Dennis McCarthy

Mar 8, 2000, 3:00:00 AM3/8/00

to

Roberts: > In these coordinates the _average_ speed

>of light _going_all_the_way_around_the_ring_ is different for

>the two directions, but the distance is the same for both rays.

>Again there is no mystery -- the light rays travel the same

>distance at different average speeds and therefore accumulate

>a phase difference.

>the two directions, but the distance is the same for both rays.

>Again there is no mystery -- the light rays travel the same

>distance at different average speeds and therefore accumulate

>a phase difference.

Dennis: Interestingly, the average speed of light for the trip is not the

average of all the speeds for each small segment of the trip. Anyway, R&T

rejected such explanations via Selleri years ago.

Allegedly, according to the rim observer, the speed of light is still

anisotropic--despite what his rulers and clock reads.

Roberts: Note that it is tricky to define "speed of light"

> in these coordinates,

Dennis: Not for etherists.

but there is indeed a well-defined

> _average_ speed of light _going_all_the_way_around_.

> This is intimitely related to the difficulty of

> synchronizing clocks in a rotating system....

Dennis: No difficulty for etherists.

Dennis McCarthy

Mar 8, 2000, 3:00:00 AM3/8/00

to

Mark Samokhvalov wrote:

> Tom Roberts wrote:

> >One might also describe this in coordinates rotating with the

> >ring interferometer. In these coordinates the _average_ speed

> >of light _going_all_the_way_around_the_ring_ is different for

> >the two directions, but the distance is the same for both rays.

> >Again there is no mystery -- the light rays travel the same

> >distance at different average speeds and therefore accumulate

> >a phase difference.

> Tom Roberts wrote:

> >One might also describe this in coordinates rotating with the

> >ring interferometer. In these coordinates the _average_ speed

> >of light _going_all_the_way_around_the_ring_ is different for

> >the two directions, but the distance is the same for both rays.

> >Again there is no mystery -- the light rays travel the same

> >distance at different average speeds and therefore accumulate

> >a phase difference.

> GR insists: in ALL RF the locally measured

> velocity of light is isotropic and = c.

> velocity of light is isotropic and = c.

Yes, _LOCALLY_. That's why I explicitly said "_AVERAGE_ speed".

Going all the way around the ring in these rotating cooridnates is

not a local measurement, and there is no constraint on the speed

of light for such non-local measurements.

> > Note that it is tricky to define "speed of light"

> > in these coordinates, but there is indeed a well-defined

> > _average_ speed of light _going_all_the_way_around_.

> > This is intimitely related to the difficulty of

> > synchronizing clocks in a rotating system....

> There's no such problem in this case with the point of emission coinciding

> with the point of reception.

Yes. As I was at pains to point out, the _AVERAGE_ speed _GOING_

_ALL_THE_WAY_AROUND_ is well defined. This is so because one can

measure this average speed with a single clock, and the difficulties

of clock synchronization do not arise. But for any other situation

(other than average speed around a closed path) one does indeed need

to synchronize clocks to measure the speed of light, and those

difficulties arise....

Tom Roberts tjro...@lucent.com

Mar 8, 2000, 3:00:00 AM3/8/00

to

Dennis McCarthy wrote:

> Dennis: Interestingly, the average speed of light for the trip is not the

> average of all the speeds for each small segment of the trip.

> Dennis: Interestingly, the average speed of light for the trip is not the

> average of all the speeds for each small segment of the trip.

Yes. Because global properties can be different from local properties.

Note that the procedures used to measure the speed of light on those

individual small segments are _different_ from both each other and

from the procedure used to measure the average, so it's not too

surprising that the results are different: each segment must

synchronize clocks differently, but the average needs no clock

synchronization at all (it's a single-clock measurement).

> Anyway, R&T

> rejected such explanations via Selleri years ago.

Selleri made a different mistake -- he claimed (incorrectly) that

in the limit R->infinity his rotating example showed an anisotropic

local speed of light. His error was that to obtain this result he

used clocks synchronized in a differrent frame from the one in which

he measured the distance travelled. That's a common undergraduate

mistake....

To the mystified onlookers: "R&T" refers to Rizzi and

Tartaglia's preprints gr-qc/9805089 and gr-qc/9904028.

In essence they show that in the rotating system the sum of

the rulers laid around the rotating rim does not measure the

_spatial_ distance around the rim, it measures distance

along a helix which does not lie in any purely spatial

3-space; when one projects this onto a purely spatial

3-space, one obtains isotropy for the speed of light in the

rotating system.

This is directly related to my comments elsewhere that this

system is _ambiguous_ -- one can select many different but

individually self-consistent coordinates to describe this.

I discussed 4 different coordinates in my post, R&T use

still different coordinates....

> Allegedly, according to the rim observer, the speed of light is still

> anisotropic--despite what his rulers and clock reads.

When you insist on making such poorly-worded statements it's no

surprise that your statements contain internal contradictions, and

you get confused.

First, I suspect you intended to say "isotropic" rather than

"anisotropic" there. But it really doesn't matter. The thing you are

missing is the distinction between a local measurement and a non-local

measurement, and the different procedures used to make them in this

case.

One can take the sum of the rulers laid around the rotating rim and

divide it by the time taken for a light pulse to circumnavigate the

rim (measured on a single clock). This is clearly an _average_

mesurement. But as R&T showed, this is not really "distance"/"time",

this is really "distance plus an admixture of time"/"time", and

calling it "speed" is really a misnomer.

Tom Roberts tjro...@lucent.com

Mar 8, 2000, 3:00:00 AM3/8/00

to Luc Bourhis

Luc Bourhis wrote:

> [1] J. Anandan, Phys. Rev. D, Vol. 24, N. 2, (1981) 338

> [2] G. Rizzi, A. Tartaglia, gr-qc/9805089

> [3] E.J. Post, Rev. Mod. Phys., Vol. 39, N. 2 (1967) 475

> [4] V. Cantoni, Il Nuovo Cimento, Vol. 57 B, N. 1 (1968) 220

> [5] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

> [1] J. Anandan, Phys. Rev. D, Vol. 24, N. 2, (1981) 338

> [2] G. Rizzi, A. Tartaglia, gr-qc/9805089

> [3] E.J. Post, Rev. Mod. Phys., Vol. 39, N. 2 (1967) 475

> [4] V. Cantoni, Il Nuovo Cimento, Vol. 57 B, N. 1 (1968) 220

> [5] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

More recent experiments:

Anderson et al, Am. J. Phys. 62#11 (1994), p975.

A more recent review, and description of a much more accurate

ring interferometer.

Hasselbach and Nicklaus, Phys. Rev. A 48#1 (1993), p143.

The Sagnac effect using electrons.

Allan et al, Science, 228 (1985), p69.

They observed the Sagnac effect using GPS satellite signals

observed simultaneously at multiple locations around the world.

Other possibly interesting articles (theory) are:

Gron, "Relativistic description of a Rotating Disk", AJP 43#10 (1975),

p869.

Mainwaring and Stedman, "Accelerated Clock Principles in Special

Relativity:, Phys. Rev. A47#5 (1993), p3611.

Berenda, "The Problem of the Rotating Disk", Phys. Rev. 62 (1942), p280.

Ashtekar and Magnon, "The Sagnac Effect in General Relativity", J. Math.

Phys. 16#2 (1975), p341.

BTW Sagnac's original papers are:

Sagnac, C.R.A.S 157 (1913), p708, p1410; J. Phys. Radium, 5th Ser.

4 (1914), p177.

Tom Roberts tjro...@lucent.com

Mar 8, 2000, 3:00:00 AM3/8/00

to

>

>Dennis McCarthy wrote:

>> Dennis: Interestingly, the average speed of light for the trip is not the

>> average of all the speeds for each small segment of the trip.

>

Roberts: >Yes. Because global properties can be different from local>Dennis McCarthy wrote:

>> Dennis: Interestingly, the average speed of light for the trip is not the

>> average of all the speeds for each small segment of the trip.

>

properties.

Dennis: But what's astounding is that the global properties (the whole) does

not equal the sum of the local properties (the parts.) This, of course, is a

newly invented, complicated, counter-intuitive and bizarre principle--that must

be believed on faith--in order to maintain allegiance to SR.

The sound Sagnac explanation and the medium Sagnac explanation in general has

no such problems.

Roberts: >Note that the procedures used to measure the speed of light on those

>individual small segments are _different_ from both each other

Dennis: You are claiming that c as the local speed of light is the *reality* of

the underlying situation. The real speed of the local speeds of light does not

add up to average global speed--according to you.

If you are arguing that a measured local speed of c is just an artifact of the

method of measurement (ie, Einstein synch procedures) then we are agreed.

>> Anyway, R&T

>> rejected such explanations via Selleri years ago.

>

Roberts: >Selleri made a different mistake -- he claimed (incorrectly) that

>in the limit R->infinity his rotating example showed an anisotropic

>local speed of light.

>

> To the mystified onlookers: "R&T" refers to Rizzi and

> Tartaglia's preprints gr-qc/9805089 and gr-qc/9904028.

> In essence they show that in the rotating system the sum of

> the rulers laid around the rotating rim does not measure the

> _spatial_ distance around the rim, it measures distance

> along a helix which does not lie in any purely spatial

> 3-space; when one projects this onto a purely spatial

> 3-space, one obtains isotropy for the speed of light in the

> rotating system.

Dennis: Exactly. So the speed of light is isotropic for the rim

observer--despite what he measures. Hmm. And it appears some other sage just

wrote: "One might also describe this in coordinates rotating with the ring

interferometer. In these coordinates the _average_ speed of light

_going_all_the_way_around_the_ring_ is different for the two directions, but

the distance is the same for both rays.

Again there is no mystery -- the light rays travel the same distance at

different average speeds and therefore accumulate a phase difference."

So apparently there is a bit of a problem with this explantion.

Roberts:> This is directly related to my comments elsewhere that this

> system is _ambiguous_

Dennis: Not in ether theory.

Roberts: -- one can select many different but

> individually self-consistent coordinates to describe this.

> I discussed 4 different coordinates in my post, R&T use

> still different coordinates....

Dennis: And you get completely different results for what the speed of light is

wrt the rim observer. Such complications don't occur in ether theory.

D:>> Allegedly, according to the rim observer, the speed of light is still

>>[now corrected:] isotropic--despite what his rulers and clock reads.

>

Roberts:

>First, I suspect you intended to say "isotropic" rather than

>"anisotropic" there. But it really doesn't matter. The thing you are

>missing is the distinction between a local measurement and a non-local

>measurement,

Dennis: Sorry. R&T comes up with a global measurement of

isotropy--contradicting your claim above.

Roberts: and the different procedures used to make them in this

>case.

>

>One can take the sum of the rulers laid around the rotating rim and

>divide it by the time taken for a light pulse to circumnavigate the

>rim (measured on a single clock). This is clearly an _average_

>mesurement. But as R&T showed, this is not really "distance"/"time",

>this is really "distance plus an admixture of time"/"time", and

>calling it "speed" is really a misnomer.

Dennis: LOL. Ahh, so what your stationary rulers read is not necessarily

distance. (Forget your rulers we have this theory you see.) Anyway, let me

again quote a sage who just recently wrote something very different. Notice

his use of the word "speed" for "distance/time" as measured by the rim

observer:

Roberts wrote: "One might also describe this in coordinates rotating with the

ring interferometer. In these coordinates the _average_ speed of light

_going_all_the_way_around_the_ring_ is different for the two directions, but

the distance is the same for both rays.

Again there is no mystery -- the light rays travel the same distance at

different average speeds and therefore accumulate

a phase difference."

That seems pretty clear: "the light rays travel the same distance at different

average speeds." You appeared to be using a "misnomer" there.

Dennis McCarthy

Mar 8, 2000, 3:00:00 AM3/8/00

to

Bourhis:

>As many people, you consider that defining the length of co- and

>counter-rotating light rays or the length of the rim itself is a trivial

>question.

>counter-rotating light rays or the length of the rim itself is a trivial

>question.

Dennis: By "A trivial question," Bourhis means using stationary rulers to

measure a length of a stationary object. Bourhis feels you can't do that.

By "many people", Bourhis means all engineers, scientists, and physicsts--who

aren't addressing the Sagnac question--*ever* who measure length in the normal

way. In fact, this was the method of measuring length for Sagnac which

**Bourhis himself agreed to** within the last few weeks--before he researched

the subject--because it's somewhat embarrassing to deny it. And in fact, I defy

Bourhis to find any experiment in the history of science where length was

determined in the way he advocates. This new anti--empirical method has been

trotted out simply for the Sagnac effect--and that's it. And its reason is to

save the special theory of relativity. It is a length that can only be

determined based on theoretical assumptions, i.e., by putting pen to paper--and

it is a length that *contradicts* what is actually observed by real

experimenters using real stationary rulers. "Forget what you measure, we have

this theory, you see. So the length around a table is longer counter-clockwise

than clockwise. I know that's not what you measure, but trust us." Geez,

that's not an extra-complicating factor, is it?

B: It is not the case at all. Indeed the naive notion of length

>require your being able to consider the whole rim or the whole rays at a

>given instant. But it can be proved that it is impossible to realize

>coherently such a "space + time splitting" because it is impossible to

>devise an unambiguous global synchronisation procedure on the whole

>ring.

Dennis: That's not only goofy but flat out false. All earth clocks and and all

satellite clocks are absolutely synchronized wrt each other in the GPS. And

the Earth and satellites are rotating. If they weren't synched, planes would

not land as safely as they do.

Bourhis:>However, just to give you a flavour of the issue, let's consider the

>following a priori straightforward situation: two particles are sent

>from some point A on the rim, in opposite directions, with the *same

>speed V with respect to the rim*. According to a clock at A, SR predicts

>that they do not come back at the same time ! This time delay T between

>the two arrivals (which does not depend on V) is observed experimentally

>in neutron experiments as a phase shift [5] between the wave functions

>of these particles (the experimental configuration is not exactly the

>one I described but it is close enough for my example to be relevant).

>

>Now consider two slow moving clocks C+ and C-, respectively co- and

>counter-rotating. If they are synchronized with a clock at point A, when

>they come back to A, C+ and C- are respectively late and ahead with

>respect to A and the difference between their reading is exactly the

>above time delay T.

>

>This shows clearly that there is much more than a speed anisotropy at

>work in Sagnac experiments,

Dennis: How on Earth does it show that? Do you still not understand that the

same effect occurs for sound--and for sound clocks? There's a sound Sagnac

effect--and if you send two sound clocks around the rim--"moving clocks C+ and

C-, respectively co- and

counter-rotating. If they are synchronized with a clock at point A, when

they come back to A, C+ and C- are respectively late and ahead with

respect to A and the difference between their reading is exactly the

above time delay T"???? All with sound. Does that also "show clearly that

there is much more than a speed anisotropy at work in [sound] Sagnac

experiments"?

Tell me Bourhis how do you measure length in the sound Sagnac experiment? Same

way? What's your explanation for sound Sagnac? Or do you use a different one?

Dennis McCarthy

Mar 8, 2000, 3:00:00 AM3/8/00

to

There is also a couple of papers by Robert Klauber on rotating systems which

mention the Sagnc effect

mention the Sagnc effect

It was Early 1999 in the Am. J. Phys. as I recall

See references therein too

Pete

Tom Roberts <tjro...@lucent.com> wrote in message

news:38C68429...@lucent.com...

Mar 8, 2000, 3:00:00 AM3/8/00

to

Luc Bourhis пишет в сообщении <38C63528...@durham.ac.uk> ...

>> path in some mysterious way become, in the course of the ring's rotation,

>> different for the clock-wise and the anti-clockwise waves?

>> 3. If not, how, with the phase velocity being equal for both waves, can a

>> phase difference accumulate?

>

>As many people, you consider that defining the length of co- and

>counter-rotating light rays or the length of the rim itself is a trivial

>question. It is not the case at all. Indeed the naive notion of length>counter-rotating light rays or the length of the rim itself is a trivial

>require your being able to consider the whole rim or the whole rays at a

>given instant. But it can be proved that it is impossible to realize

>coherently such a "space + time splitting" because it is impossible to

>devise an unambiguous global synchronisation procedure on the whole

>ring. I will not give this demonstration because it is too complicated

>to expose it in ASCII. The interesting reader is refered to [4] and

>references therein.

>to expose it in ASCII. The interesting reader is refered to [4] and

>references therein.

An excellent example ot high-brow relativistic blabber just to save the,

apparently, initially false constant c assumption. There are no problems in

defining lengths, if it's the same for both rays, if not, there's again no

need to define them - just to cite a PHYSICAL cause which makes two lengths

out of one when the ring rotates wrt stars, and certainly no sync problems.

For an etherist, the cause is simple and one for all RFs - it's constant

speed of light in ether at rest wrt stars. A relativist shrouds the problem

in so many words and formulae, and still fails to come up with an answer.

>

>However, just to give you a flavour of the issue, let's consider the

>following a priori straightforward situation: two particles are sent

>from some point A on the rim, in opposite directions, with the *same

>speed V with respect to the rim*. According to a clock at A, SR predicts

>that they do not come back at the same time !

A clock has nothing to do here - a coincidence indicator does the job. What

d'you mean by "the same speed"? D'you postulate it? If so, it's exactly the

same unanswered question (2).

This time delay T between

>the two arrivals (which does not depend on V) is observed experimentally

>in neutron experiments as a phase shift [5] between the wave functions

>of these particles (the experimental configuration is not exactly the

>one I described but it is close enough for my example to be relevant).

In experiment, postulating equal V's is not enough. You must make them

equal - most probably, it was assumed that opposite equal energy particles

have equal V's wrt to the rotating ring - a wrong assumption from the

etherist viewpoint because m(V) is wrt ether.

>

>Now consider two slow moving clocks C+ and C-, respectively co- and

>counter-rotating. If they are synchronized with a clock at point A, when

>they come back to A, C+ and C- are respectively late and ahead with

>respect to A and the difference between their reading is exactly the

>above time delay T.

This, again is not surprising, since time dilation in clocks moving wrt

ether is an experimental fact attributable to ether wind action on the

frequency standard. The ether approach would, in addition, expect a

dependence on the clock type - a clock with a directional frequency standard

(e.g., a piezoquartz resonator) could change its ticking rate with a change

in orientation. By the way, there's sufficient experimental evidence on the

ticking rate of satellite clocks to belie the equivalence pinciple - it's

different on different satellites, whereas conditions inside them should be

indistinguishable.

>

>This shows clearly that there is much more than a speed anisotropy at

>work in Sagnac experiments, even if an etherist might believe at first

>that it is a possible explanation for Sagnac experiments based on light

propagation.

By no means. For an etherist, there's nothing more than speed anisotropy in

Sagnac's experiment, but in other experiments, there are other ether wind

effects

[1] J. Anandan, Phys. Rev. D, Vol. 24, N. 2, (1981) 338

>[2] G. Rizzi, A. Tartaglia, gr-qc/9805089

>[3] E.J. Post, Rev. Mod. Phys., Vol. 39, N. 2 (1967) 475

>[4] V. Cantoni, Il Nuovo Cimento, Vol. 57 B, N. 1 (1968) 220

>[5] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

Mar 8, 2000, 3:00:00 AM3/8/00

to

On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

(in message <20000308124906...@ng-fm1.aol.com>):

(in message <20000308124906...@ng-fm1.aol.com>):

>> This shows clearly that there is much more than a speed anisotropy at

>> work in Sagnac experiments,

>

> Dennis: How on Earth does it show that? Do you still not understand that the

> same effect occurs for sound--and for sound clocks?

What I have explained is treated extensively and precisely in the references

I have given. So it is now your turn: please show your math or at least some

references to them and please do not forget to explain the effects for the

two particles moving with the same speed wrt the rim: no speed anisotropy by

definition there.

--

Luc Bourhis

Center of Particle Physics/University of Durham

Mar 9, 2000, 3:00:00 AM3/9/00

to

On Wed, 8 Mar 2000 19:15:16 +0000, Mark Samokhvalov wrote

(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

>> As many people, you consider that defining the length of co- and

>> counter-rotating light rays or the length of the rim itself is a trivial

>> question. It is not the case at all. Indeed the naive notion of length

>> require your being able to consider the whole rim or the whole rays at a

>> given instant. But it can be proved that it is impossible to realize

>> coherently such a "space + time splitting" because it is impossible to

>> devise an unambiguous global synchronisation procedure on the whole

>> ring. I will not give this demonstration because it is too complicated

>> to expose it in ASCII. The interesting reader is refered to [4] and

>> references therein.

>

> An excellent example ot high-brow relativistic blabber just to save the,

> apparently, initially false constant c assumption. There are no problems in

> defining lengths, if it's the same for both rays, if not, there's again no

> need to define them - just to cite a PHYSICAL cause which makes two lengths

> out of one when the ring rotates wrt stars, and certainly no sync problems.

> For an etherist, the cause is simple and one for all RFs - it's constant

> speed of light in ether at rest wrt stars. A relativist shrouds the problem

> in so many words and formulae, and still fails to come up with an answer.

Before defining you as an etherist, you have to precise clearly what ether

theory you want to use to model a Sagnac experiment. Be careful because in

order to escape the difficulties encountered with SR, you have to avoid

LET-like theories which have Lorentz transforms embedded in them. But then

you are most surely in trouble with Michelson & Morley, Kennedy & Thorndike

or Doppler because an Ether theory compatible with these experiments is

equivalent to SR as long as we are concerned with observable predictions. So

I would say that this is the typical answer of an etherist on this forum:

taught about what is the situation in pedagogical terms and referred to

serious references to obtain a deeper knowledge, he comes with a ghost

rebutal not supported by any scientific argument. I am disappointed to see

that you have not better prepared your troll.

>> However, just to give you a flavour of the issue, let's consider the

>> following a priori straightforward situation: two particles are sent

>> from some point A on the rim, in opposite directions, with the *same

>> speed V with respect to the rim*. According to a clock at A, SR predicts

>> that they do not come back at the same time !

>

> A clock has nothing to do here

It could have if one was measuring the arrival times ....

> - a coincidence indicator does the job.

... but indeed one performs quantum experiment and observe the interferences

between the particles going in opposite directions. However the phase shift

is directly proportional to the time delay.

> What d'you mean by "the same speed"? D'you postulate it?

The same speed. I can not be clearer. It is imposed by the experimental

configuration. See below.

> If so, it's exactly the same unanswered question (2).

The 3 following objects have different length:

- the trajectory of a co-rotating particle

- the trajectory of a counter-rotating particle

- the rim

if one works in the non-inertial frame whose world lines are defined by the

following parametric equations in some inertial frame:

x0 = t

x1 = a cos(w t) - b sin(w t)

x2 = a sin(w t) + b cos(w t)

x3 = 0,

with (a^2+b^2)^(1/2) being the radius of the rim and w its rotation speed.

>> This time delay T between

>> the two arrivals (which does not depend on V) is observed experimentally

>> in neutron experiments as a phase shift [5] between the wave functions

>> of these particles (the experimental configuration is not exactly the

>> one I described but it is close enough for my example to be relevant).

>

> In experiment, postulating equal V's is not enough. You must make them

> equal - most probably, it was assumed that opposite equal energy particles

> have equal V's wrt to the rotating ring - a wrong assumption from the

> etherist viewpoint because m(V) is wrt ether.

Again which Ether theory ? Anyway for the non-relativistic particles used

here, de Broglie law relating the wave-length lambda, and therefore the

energy of the particles, their mass m and their speed v,

lambda = h/(m v)

is exceptionaly well verified. Then the two beams are obtained from one

incoming beam by a Bragg diffraction through a layer of silicon. The optical

nature of the phenomena guaranties that the wave-length of the two outgoing

beams is the same. Therefore the situation is the one I have described and

you have only forced me to explain the details related to my remark between

parentheses. Note that the same kind of experiments have been made with

electrons [7] (thanks to Tom Roberts for the reference).

So now how can you explain the experimental results ?

>> Now consider two slow moving clocks C+ and C-, respectively co- and

>> counter-rotating. If they are synchronized with a clock at point A, when

>> they come back to A, C+ and C- are respectively late and ahead with

>> respect to A and the difference between their reading is exactly the

>> above time delay T.

>

> This, again is not surprising, since time dilation in clocks moving wrt

> ether is an experimental fact attributable to ether wind action on the

> frequency standard.

What is tremendously interesting however is that one finds the same T for

this shift between clocks and for the delay between the arrival time of

particles rotating in opposite direction even if a priori there is no links

between these two configurations. If one remembers that the same geometry of

spacetime is at work, everything becomes clear and indeed the important point

is of course that SR gives the correct predictions for all these effects. And

Ether theories ?

> The ether approach would, in addition, expect a

> dependence on the clock type - a clock with a directional frequency standard

> (e.g., a piezoquartz resonator) could change its ticking rate with a change

> in orientation. By the way, there's sufficient experimental evidence on the

> ticking rate of satellite clocks to belie the equivalence pinciple - it's

> different on different satellites, whereas conditions inside them should be

> indistinguishable.

I do not understand : do you say the the equivalence principle can be

believed or that it is ruled out ? I do not know any experimental data

supporting the latter.

[4] V. Cantoni, Il Nuovo Cimento, Vol. 57 B, N. 1 (1968) 220

[5] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

[6] C.M. Will, gr-qc/9811036

[7] Allan et al, Science, 228 (1985), p69.

Mar 9, 2000, 3:00:00 AM3/9/00

to

>

>On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

>(in message <20000308124906...@ng-fm1.aol.com>):

>

>>> This shows clearly that there is much more than a speed anisotropy at

>>> work in Sagnac experiments,

>>

>> Dennis: How on Earth does it show that? Do you still not understand that

>the

>> same effect occurs for sound--and for sound clocks?

>

Bourhis: >What I have explained is treated extensively and precisely in the>On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

>(in message <20000308124906...@ng-fm1.aol.com>):

>

>>> This shows clearly that there is much more than a speed anisotropy at

>>> work in Sagnac experiments,

>>

>> Dennis: How on Earth does it show that? Do you still not understand that

>the

>> same effect occurs for sound--and for sound clocks?

>

references

>I have given. > So it is now your turn: please show your math or at least some

>references to them

Dennis: You have given no evidence for your claim above. That's just a strange

Bourhis conclusion.

Moreover, when you first came to this thread I had to show you the precise

mathematical description of sound Sagnac, ether Sagnac and sound clocks. It's

an obvious physical fact that no one denies--and takes three lines of algebra.

Also, it took me two weeks of getting past all of your ridiculous

objections--but you finally understood it (sound and ether Sagnac.) I'm not

going through it again. If you don't believe sound Sagnac occurs or just want

to deny obvious physical facts that you find inconvenient and irritating, then

this discussion is not worth my time and you are not on an objective search for

the truth.

Also, you gave references for the interesting argument that the length of a

rim is not the same CW as CCW for a rim observer. Very strange to say the

least.

You haven't replied to the following:

Bourhis:

>As many people, you consider that defining the length of co- and

>counter-rotating light rays or the length of the rim itself is a trivial

>question.

Dennis: By "A trivial question," Bourhis means using stationary rulers to

measure a length of a stationary object. Bourhis feels you can't do that.

By "many people", Bourhis means all engineers, scientists, and physicsts--who

aren't addressing the Sagnac question--*ever* who measure length in the normal

way. In fact, this was the method of measuring length for Sagnac which

**Bourhis himself agreed to** within the last few weeks--before he researched

the subject--because it's somewhat embarrassing to deny it. And in fact, I defy

Bourhis to find any experiment in the history of science where length was

determined in the way he advocates. This new anti--empirical method has been

trotted out simply for the Sagnac effect--and that's it. And its reason is to

save the special theory of relativity. It is a length that can only be

determined based on theoretical assumptions, i.e., by putting pen to paper--and

it is a length that *contradicts* what is actually observed by real

experimenters using real stationary rulers. "Forget what you measure, we have

this theory, you see. So the length around a table is longer counter-clockwise

than clockwise. I know that's not what you measure, but trust us." Geez,

that's not an extra-complicating factor, is it?

Dennis McCarthy

Mar 9, 2000, 3:00:00 AM3/9/00

to

>

>On Wed, 8 Mar 2000 19:15:16 +0000, Mark Samokhvalov wrote

>(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

>

>>> As many people, you consider that defining the length of co- and

>>> counter-rotating light rays or the length of the rim itself is a trivial

>>> question. It is not the case at all. Indeed the naive notion of length

>>> require your being able to consider the whole rim or the whole rays at a

>>> given instant. But it can be proved that it is impossible to realize

>>> coherently such a "space + time splitting" because it is impossible to

>>> devise an unambiguous global synchronisation procedure on the whole

>>> ring. I will not give this demonstration because it is too complicated

>>> to expose it in ASCII. The interesting reader is refered to [4] and

>>> references therein.

>>

>> An excellent example ot high-brow relativistic blabber just to save the,

>> apparently, initially false constant c assumption. There are no problems in

>> defining lengths, if it's the same for both rays, if not, there's again no

>> need to define them - just to cite a PHYSICAL cause which makes two lengths

>> out of one when the ring rotates wrt stars, and certainly no sync problems.

>> For an etherist, the cause is simple and one for all RFs - it's constant

>> speed of light in ether at rest wrt stars. A relativist shrouds the problem

>> in so many words and formulae, and still fails to come up with an answer.

>

B:>Before defining you as an etherist, you have to precise clearly what ether >On Wed, 8 Mar 2000 19:15:16 +0000, Mark Samokhvalov wrote

>(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

>

>>> As many people, you consider that defining the length of co- and

>>> counter-rotating light rays or the length of the rim itself is a trivial

>>> question. It is not the case at all. Indeed the naive notion of length

>>> require your being able to consider the whole rim or the whole rays at a

>>> given instant. But it can be proved that it is impossible to realize

>>> coherently such a "space + time splitting" because it is impossible to

>>> devise an unambiguous global synchronisation procedure on the whole

>>> ring. I will not give this demonstration because it is too complicated

>>> to expose it in ASCII. The interesting reader is refered to [4] and

>>> references therein.

>>

>> An excellent example ot high-brow relativistic blabber just to save the,

>> apparently, initially false constant c assumption. There are no problems in

>> defining lengths, if it's the same for both rays, if not, there's again no

>> need to define them - just to cite a PHYSICAL cause which makes two lengths

>> out of one when the ring rotates wrt stars, and certainly no sync problems.

>> For an etherist, the cause is simple and one for all RFs - it's constant

>> speed of light in ether at rest wrt stars. A relativist shrouds the problem

>> in so many words and formulae, and still fails to come up with an answer.

>

>theory you want to use to model a Sagnac experiment. Be careful because in

>order to escape the difficulties encountered with SR, you have to avoid

>LET-like theories which have Lorentz transforms embedded in them.

>order to escape the difficulties encountered with SR, you have to avoid

>LET-like theories which have Lorentz transforms embedded in them.

Dennis: You are coming close to outright dishonesty. The only person in the

world who follows the type of LET that you use to confuse situations and

complicate Sagnac is you. All other known etherists (Michelson, Sagnac, Ives,

etc., and those on these boards and all whom I know personally), no matter what

the ether theory, derive the Sagnac effect quite simply with the Galilean

analysis.

Now, unfortunately, the following involves physical reasoning, but I'll still

try. In the Sagnac effect, the Lorentz contraction can be disregarded by

Lorentzians because there is only one rim and so LC has an equal effect on both

path lengths. Also, no clock movements or synch procedures need to be made.

Thus, the Galilean nature of light is clearly recovered in the

experiment--because there are no relevant deformations of the measuring devices

to counteract this Galilean nature. And **all** etherists whom I know believe

in the underlying Galilean nature of light. Lorentzians apply the Lorentzian

corrections only when measuring devices are altered in a relevant way. If not,

then the Galilean nature is recovered, and as you know, I hope, it takes 3

lines of algebra to produce Sagnac.

B: But then

>you are most surely in trouble with Michelson & Morley, Kennedy & Thorndike

>or Doppler because an Ether theory compatible with these experiments is

>equivalent to SR as long as we are concerned with observable predictions.

Dennis: That's false. Obviously. IGS theory, for example, fits the known

experiments. And Lorentz contraction does not need to be assumed.

B:So

>I would say that this is the typical answer of an etherist on this forum:

>taught about what is the situation in pedagogical terms and referred to

>serious references to obtain a deeper knowledge, he comes with a ghost

>rebutal not supported by any scientific argument.

Dennis: The etherist argument was put forth by Sagnac in 1913 in the original

paper on the subject. The Galilean analysis that predicts the result came

centuries before that. It is unfortunate that you still pretend to be unaware

of it.

Dennis McCarthy

Mar 9, 2000, 3:00:00 AM3/9/00

to

Mark Samokhvalov wrote:

> Luc Bourhis пишет в сообщении <38C63528...@durham.ac.uk> ...

> >

> >However, just to give you a flavour of the issue, let's consider the

> >following a priori straightforward situation: two particles are sent

> >from some point A on the rim, in opposite directions, with the *same

> >speed V with respect to the rim*. According to a clock at A, SR predicts

> >that they do not come back at the same time !

>

> A clock has nothing to do here - a coincidence indicator does the job. What

> d'you mean by "the same speed"? D'you postulate it? If so, it's exactly the

> same unanswered question (2).

No, our observers measure it. They, for some strange reason, are under the

impression that the speeds they measure with their clocks and rulers are

the actual speeds in their frame.

I suppose _you're_ going to say that their measurements are invalid for

some reason now, aren't you...

Mar 9, 2000, 3:00:00 AM3/9/00

to

On 08 Mar 2000 djm...@aol.com (Dennis McCarthy) wrote:

>That paragraph I quoted does not confine its "attention to

>inertial coordinates." Instead, it states "but of course such

>coordinates are necessarily accelerating (viz., rotating), and

>special relativity does not assume light speed to be isotropic

>with respect to non-inertial coordinates."

>That paragraph I quoted does not confine its "attention to

>inertial coordinates." Instead, it states "but of course such

>coordinates are necessarily accelerating (viz., rotating), and

>special relativity does not assume light speed to be isotropic

>with respect to non-inertial coordinates."

That web page mentions analyzing the Sagnac device in terms of

coordinates rigidly fixed to the ring, notes that these are

necessarily accelerating coordinates, notes that lightspeed need

not be c with respect to such coordinates, comments on how one

might imagine that this leads to a contradiction, since it IS

possible to define a coordinate system "in terms of which the

position of a point fixed on the disk is independent of time", and

then defers further discussion of accelerated coordinates until

later, saying "For the moment, let's just confine our attention

to inertial coordinates...", following which appears an analysis

of the Sagnac device in terms of the co-moving inertial coordinates

of a fixed point on the ring. In the subsequent sections it

describes the helical locus of local simultaneity implied by the

the sequence of co-moving inertial coordinates, and then gives an

account in terms of a single accelerating coordinate system and

the resulting pseudo-gravitational potentials. In summary, you

misread, misunderstood, and misrepresented the reference (IMHO).

On 08 Mar 2000 djm...@aol.com (Dennis McCarthy) wrote:

>Are you arguing that it is theoretically acceptable for the

>SR explanation to assume that the speed of light is non-

>isotropic for the rim observer?

Fundamentally the Sagnac effect from an SR perspective is due

to the difference in optical path lengths, but it's possible to

define spatial and temporal parameters in terms of which this

optical path lengh difference can be expressed as an equivalent

anisotropy in the "speed of light" at various points around

the rim. Of course, this involves defining "speed" in terms

of distances and times that are not components of a single

inertial coordinate system. The reference web page describes

in detail one way of doing this.

You have to be careful not to confuse the different approaches

that can be taken to describe the operation of a Sagnac device.

First, since the Sagnac effect is not essentially relativistic,

it's possible to get the right answer by taking a Galilean approach.

Second, there is the drop-dead simple SR method in terms of a single

system of inertial coordinates, which is how anyone in their right

mind approaches the problem. Needless to say, the speed of light

is isotropic with respect to this parameterization.

Now, if we get bored doing things the sensible way, there are (at

least) two ways that we can describe "how this looks" in terms of

coordinates in which an observer fixed on the rim is stationary.

The first way is to use momentarily co-moving inertial coordinates,

which vary as the disk rotates. This is still an "SR explanation"

in the sense that no pseudo-gravitational potentials are invoked,

but it's really a composite view over a sequence of coordinate

systems, each of which is inertial in itself, but the union of

which does not constitute a single inertial frame. Instead it

yields a helical locus of simultaneity, and of course a difference

in the effective path lengths in the two directions around the

rim. In this case, as mentioned above, it's possible to define

space and time parameters in such a way that we can express the

difference in path lengths as an equivalent difference in light

"speed", on the understanding that this speed is not defined in

terms of components of an inertial coordinate system. (There's

not much reason to actually DO this, other than to show that

it's possible.)

Another approach is to use a single accelerating coordinate

system, with respect to which a given point on the rim is

*permanently* stationary. This requires the introduction of

pseudo-gravitational potentials to account for the accelerations

to which the various points on the rim are subjected with respect

to these accelerated coordinates. Some people would call this

a "GR" approach, but since the spacetime is still flat, this is

debatable. In any case, the key here is to properly account

for ALL the accelerations, including the Coriolis acceleration,

which turns out to be the dominant factor in establishing the

pseudo-gravitational potential corresponding to the differential

progress of light around the rim in the two directions, because

the Coriolis effect is different for the two directions.

This is all standard stuff, and has been explained many times

before. For example, there's a nice overview in Ciufolini and

Wheeler's "Gravitation and Inertia".

On 08 Mar 2000 djm...@aol.com (Dennis McCarthy) wrote:

>...the only "mistake" of Selleri that was *alleged* by R&T was

>that the paradox negates the SR view.

Selleri claimed (in a self-published note) that Sagnac was

inconsistent with special relativity. Rizzi and Tartaglia

published a rebutal, pointing out that Selleri was mistaken (as

if this wasn't obvious), and they highlighted one particular

flaw in Selleri's reasoning, sufficient to invalidate his claim.

However, R&T did not detect (or at least didn't mention) ALL of

the errors in Selleri's reasoning. (This would have made for a

MUCH longer paper.) They focused only on the most interesting

error in his reasoning, one that has been committed by other

people as well, namely, the assumption that we can always define

a single-valued foliation of simultaneity for an accelerating

observer. Of course, this assumption is false, and has always

been known to be false, i.e., this was not a discovery of R&T.

They simply published their note to rebut Selleri and as an

informational service to highlight an interesting aspect of

special relativity.

One of Selleri's errors that R&T failed to mention in their

little rebutal note was his simple failure to correctly evaluate

the "anisotropic speed ratio" in the limit of increasing radius,

even according to his own (flawed) premises. He asserted that

this ratio remains constant as the radius increases to infinity,

leading to (he claimed) a conflict with special relativity in

the limit of *linear* light paths. The correct analysis shows

that the deviation from 1 of the "anisotropic ratio" is always

exactly proportional to the *angular* travel of the device

during the transit of light, and this remains true in the

limit as the radius increases to infinity.

On 08 Mar 2000 djm...@aol.com (Dennis McCarthy) wrote:

>RChan: Again, just so no one is misled, Dennis is completely

>incorrect in his assessment. There is nothing mysterious about

>accelerating coordinate systems, at least not to anyone who

>understands them.

>

>Dennis: Are you trying to argue that R&T's position regarding

>the Sagnac effect was *not* that the "path becomes, in the

>course of the ring's rotation, different for the clock-wise

>and the anti-clockwise waves"--even for the rim observer?

Why on Earth would I be trying to argue that? Let's see now,

you're saying that R&T are saying that the path lengths are

different due to the absolute rotation of the ring. Gosh,

what an insight. How mysterious! Actually, that's what I

(and everyone else, as far as I can tell) have been saying

all along, including the reference web page, which says "Notice

that this anisotropy ... for any inertial frame is actually

in the distance travelled, not the speed of travel", and then

goes on to describe the helical locus of simultaneity, etc.

What I WAS arguing is that "There is nothing mysterious about

Mar 9, 2000, 3:00:00 AM3/9/00

to

Luc Bourhis пишет в сообщении

To my knowledge, ALL experiments performed to detect the effect of the

Earth's orbital velocity on physical processes, including my own to detect

the anisotropy of electrophysical parameters induced by it, have produced

nil results. Together with the existence of star aberration, this could be

explained by ether drag by the Earth's gravitational field and verified by

any of the aforementioned experiments on board satellites, or on the Earth

by such experiments sensitive enough to detect the effects of Earth's

rotation velocity. Perhaps, such experiments have already been performed -

any information?

Clearly, a case when sollipsism comes in conflict with reality - different

results obtained by reasoning with no physical cause. SR was originally

constructed not as a physical, but as a metric theory - had another signal

carrier (e.g., fast particles) been used, the results would have been

different. Had different signal carriers been used jointly, all ambiguity

(=relativity), would have been removed.

Indeed, during the XX-th century triumphs of theoretical physics elated the

intellectual elite aleready influenced by sollipsist philosophy to the

extent that they thought they could construct reality. It the same with

quantum physics: all sorts of weird hypotheses have been advanced to explain

the interference of isolated quanta instead of aknowledging the simple fact

of their division and propagation in the form of sub-quantum oscillations.

>>> This time delay T between

>>> the two arrivals (which does not depend on V) is observed experimentally

>>> in neutron experiments as a phase shift [5] between the wave functions

>>> of these particles (the experimental configuration is not exactly the

>>> one I described but it is close enough for my example to be relevant).

>>

>> In experiment, postulating equal V's is not enough. You must make them

>> equal - most probably, it was assumed that opposite equal energy

particles

>> have equal V's wrt to the rotating ring - a wrong assumption from the

>> etherist viewpoint because m(V) is wrt ether.

>

>Again which Ether theory ? Anyway for the non-relativistic particles used

>here, de Broglie law relating the wave-length lambda, and therefore the

>energy of the particles, their mass m and their speed v,

> lambda = h/(m v) is exceptionaly well verified. Then the two beams are

obtained from one

>incoming beam by a Bragg diffraction through a layer of silicon. The

optical

>nature of the phenomena guaranties that the wave-length of the two outgoing

>beams is the same. Therefore the situation is the one I have described and

>you have only forced me to explain the details related to my remark between

>parentheses. Note that the same kind of experiments have been made with

>electrons [7] (thanks to Tom Roberts for the reference).

>

>So now how can you explain the experimental results ?

>The experimental fact of inertial mass vs V dependence explained/predicted

by several theories, includung SR. With the ether concept, V is measured wrt

ether, and therefore in the ring's RF it will be different for co- and

counter-rotating equal energy particles.

>>> Now consider two slow moving clocks C+ and C-, respectively co- and

>>> counter-rotating. If they are synchronized with a clock at point A, when

>>> they come back to A, C+ and C- are respectively late and ahead with

>>> respect to A and the difference between their reading is exactly the

>>> above time delay T.

>>

>> This, again is not surprising, since time dilation in clocks moving wrt

>> ether is an experimental fact attributable to ether wind action on the

>> frequency standard.

>

>What is tremendously interesting however is that one finds the same T for

>this shift between clocks and for the delay between the arrival time of

>particles rotating in opposite direction even if a priori there is no links

>between these two configurations. If one remembers that the same geometry

of

>spacetime is at work, everything becomes clear and indeed the important

point

>is of course that SR gives the correct predictions for all these effects.

And

>Ether theories ?

No space-time needed. Suffice it that both effects are described by small

terms quadratic in V. Integration over travel time produces the result.

>

>> The ether approach would, in addition, expect a

>> dependence on the clock type - a clock with a directional frequency

standard

>> (e.g., a piezoquartz resonator) could change its ticking rate with a

change

>> in orientation. By the way, there's sufficient experimental evidence on

the

>> ticking rate of satellite clocks to belie the equivalence pinciple - it's

>> different on different satellites, whereas conditions inside them should

be

>> indistinguishable.

>

>I do not understand : do you say the the equivalence principle can be

>believed or that it is ruled out ? I do not know any experimental data

>supporting the latter.

>

I mean, it doesn't work, because the clocks on satellites at different

altitudes tick differently.

Mar 9, 2000, 3:00:00 AM3/9/00

to

Dennis McCarthy wrote:

>

> >

> >On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

> >(in message <20000308124906...@ng-fm1.aol.com>):

> >

> >>> This shows clearly that there is much more than a speed anisotropy at

> >>> work in Sagnac experiments,

> >>

> >> Dennis: How on Earth does it show that? Do you still not understand that the

> >> same effect occurs for sound--and for sound clocks?

> >

>

> >

> >On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

> >(in message <20000308124906...@ng-fm1.aol.com>):

> >

> >>> This shows clearly that there is much more than a speed anisotropy at

> >>> work in Sagnac experiments,

> >>

> >> Dennis: How on Earth does it show that? Do you still not understand that the

> >> same effect occurs for sound--and for sound clocks?

> >

> >What I have explained is treated extensively and precisely in the references

> >I have given. So it is now your turn: please show your math or at least some

> >references to them

>

> Dennis: You have given no evidence for your claim above. That's just a strange

> Bourhis conclusion.

> >I have given. So it is now your turn: please show your math or at least some

> >references to them

>

> Dennis: You have given no evidence for your claim above. That's just a strange

> Bourhis conclusion.

For the moment I have not seen either Tom Roberts or Steve Carlip

contradicting me. Usually they do not hesitate to point out errors in

whatever messages they are made. Do you think you know better Special

and General Relativity than all of us ?

> Moreover, when you first came to this thread I had to show you the precise

> mathematical description of sound Sagnac, ether Sagnac and sound clocks. It's

> an obvious physical fact that no one denies--and takes three lines of algebra.

For Sagnac experiment, you have shown only a mere Galilean analysis

which does give the correct result for light only because terms in

(v/c)^2 are experimentally not observable. However this same kind of

analysis predicts no delay between the comeback of two particles sent

simultaneously in opposite direction with the same speed with respect to

the rim. SR predicts on the contrary a delay and this effects is

observed for neutron and electrons [1,2]. So how do you reconciliate

your point of view with experimental results ? Surely not with clocks.

Moreover your sound clocks are the analogs of Einstein light clocks :

waves bouncing between two walls. How do you manage to model mechanical

clocks, atomic clocks, molecular clocks, instable particles decaying

through weak interaction, instable particles decaying through strong

interaction with such a kindergarten *non-quantum* model ? Is it that

you have to postulate that this simple analogy can be extended to treat

any kind of periodical phenomena ? But are you not using the Postulate

of Relativity then ? If fact you have advocated a long time ago what you

called PLET (Poincarre LET), i.e. LET + PoR. Well it was before your

infatuation for IGS.

> Also, you gave references for the interesting argument that the length of a

> rim is not the same CW as CCW for a rim observer. Very strange to say the

> least.

Strange is not by itself a scientific comment. Furthermore you are

mistaken. Co- and counter-rotating light rays do not have the same

lengths and these lengths are different from the one of the rim.

Precisely (I have to be careful: Tom and Steve are around in this

thread) this is true in the non-inertial frame whose world lines are

paramametrized by:

x0 = t

x1 = R cos(w t)

x2 = R sin(w t)

x3 = 0

where R is the radius of the rim and w its angular speed (as you see

this frame is intuitively the rim). This comes from the fact that

neither the rim nor the light rays are well defined geometrical objects

entirely embedded in space at a given instant.

This is a definitive result of SR and/or GR, and of course of LET -- the

theory exposed by Lorentz in 1904 can indeed be extended to deal with

non-inertial frame as SR is and this results in the same framework since

SR and LET are equivalent for inertial motions.

> You haven't replied to the following:

Sun-Tzu said : "When involved in a guerilla, launch first the attacks

which do not cost you anything".

> >As many people, you consider that defining the length of co- and

> >counter-rotating light rays or the length of the rim itself is a trivial

> >question.

>

> Dennis: By "A trivial question," Bourhis means using stationary rulers to

> measure a length of a stationary object. Bourhis feels you can't do that.

> By "many people", Bourhis means all engineers, scientists, and physicsts--who

> aren't addressing the Sagnac question--*ever* who measure length in the normal

> way.

That is to say in situations where relativistic effects are completely

negligeable. That is to say by working with a Galilean framework which

was indeed a good approximation.

> In fact, this was the method of measuring length for Sagnac which

> **Bourhis himself agreed to** within the last few weeks--before he researched

> the subject--because it's somewhat embarrassing to deny it. And in fact, I defy

> Bourhis to find any experiment in the history of science where length was

> determined in the way he advocates.

The definition of length used in [4] and precisely explained in [3] is

used routinely in GR for a very long time. Moller [5] described it in a

book published in the 60's and it is therefore even older. It is a very

general definition because it is equivalent locally to the kind of

intuitive method you advocate which uses rulers -- semi-precisely, it

transforms the measurement of the length of a 1-dimensional body in a

frame R into an infinite succession of length measurements at successive

points P by inertial observers moving with the same speed as R at this

point P. So this means naively that for infinitesimal lengths we are

back to our usual rulers.

Difficulties do only occur when one considers global properties, the

whole rim for example. These difficulties are seen only for a particular

class of non-inertial frames (see [5] p. 248 for a complete analysis)

and rotating frames are in this class. And yes this is a new effect

predicted by Special Relativity and LET but not by Galilean Relativity.

But how is it possible to be surprised by this fact ?

> This new anti--empirical method has been

> trotted out simply for the Sagnac effect--and that's it. And its reason is to

> save the special theory of relativity.

It is blatantly wrong as explained above. Before criticizing modern

physic one is supposed to learn it. You know you can not get this

knowledge solely from this newsgroup. Contributors like me do not have

the time or the energy to give the best pedagogical explanations and we

have to be often too concise or sketchy.

> It is a length that can only be

> determined based on theoretical assumptions, i.e., by putting pen to paper--and

> it is a length that *contradicts* what is actually observed by real

> experimenters using real stationary rulers.

You are again completely confused. An observer moving infinitely slowly

along the rim will measure the perimeter:

L = 2 pi R/(1-(R Omega)^2)^(1/2)

in units where c=1. But this is not the length of a light ray

propagating along the rim in the non-inertial frame I have defined

precisely above. Now how do you propose to measure with rulers the

length of a light ray ?

[1] S.A. Werner et al, Phys. Rev. A 21 (1980) 1419

[2] Hasselbach and Nicklaus, Phys. Rev. A 48#1 (1993), p143.

[3] J. Anandan, Phys. Rev. D, Vol. 24, N. 2, (1981) 338

[4] G. Rizzi, A. Tartaglia, gr-qc/9805089

[5] C. Moller, The Theory of Relativity (Oxford 1952)

Mar 9, 2000, 3:00:00 AM3/9/00

to

>

>>Dennis: Are you trying to argue that R&T's position regarding

>>the Sagnac effect was *not* that the "path becomes, in the

>>course of the ring's rotation, different for the clock-wise

>>and the anti-clockwise waves"--even for the rim observer?

>

Chan: Why on Earth would I be trying to argue that? Let's see now,>>Dennis: Are you trying to argue that R&T's position regarding

>>the Sagnac effect was *not* that the "path becomes, in the

>>course of the ring's rotation, different for the clock-wise

>>and the anti-clockwise waves"--even for the rim observer?

>

>you're saying that R&T are saying that the path lengths are

>different due to the absolute rotation of the ring. Gosh,

>what an insight. How mysterious! Actually, that's what I

>(and everyone else, as far as I can tell) have been saying

>all along, including the reference web page, which says "Notice

>that this anisotropy ... for any inertial frame is actually

>in the distance travelled, not the speed of travel",

Dennis: Perhaps, you should read the paper again? R&T are arguing the distance

is different according to the frame **for the rim observer**--for the frame of

the rim. That means the desk your computer is on would be longer CCW than

CW--according to *you*--who is stationary wrt the desk despite what you

measure.

And apparently that result is "mysterious" --as you didn't understand it.

I have snipped your other mistakes as they all relate to that point.

Dennis McCarthy

Mar 9, 2000, 3:00:00 AM3/9/00

to

Dennis McCarthy wrote:

>

> >

> >On Wed, 8 Mar 2000 19:15:16 +0000, Mark Samokhvalov wrote

> >(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

> >

>

> >

> >On Wed, 8 Mar 2000 19:15:16 +0000, Mark Samokhvalov wrote

> >(in message <8a68pl$utl$1...@gavrilo.mtu.ru>):

> >

> >Before defining you as an etherist, you have to precise clearly what ether

> >theory you want to use to model a Sagnac experiment. Be careful because in

> >order to escape the difficulties encountered with SR, you have to avoid

> >LET-like theories which have Lorentz transforms embedded in them.

>

> >theory you want to use to model a Sagnac experiment. Be careful because in

> >order to escape the difficulties encountered with SR, you have to avoid

> >LET-like theories which have Lorentz transforms embedded in them.

>

> Dennis: You are coming close to outright dishonesty. The only person in the

> world who follows the type of LET that you use to confuse situations and

> complicate Sagnac is you. All other known etherists (Michelson, Sagnac, Ives,

> etc., and those on these boards and all whom I know personally), no matter what

> the ether theory, derive the Sagnac effect quite simply with the Galilean

> analysis.

> world who follows the type of LET that you use to confuse situations and

> complicate Sagnac is you. All other known etherists (Michelson, Sagnac, Ives,

> etc., and those on these boards and all whom I know personally), no matter what

> the ether theory, derive the Sagnac effect quite simply with the Galilean

> analysis.

And you are then using incoherent ad hoc solution ruled out

experimentaly if you advocate a mere Galilean analysis of the Sagnac

effect. Indeed,

1) Are you really ready to promote LET for Michelson & Morley, Kennedy &

Thorndike, Trouton & Noble, ..... while you advocate a Galilean analysis

as the fundamental theory for Sagnac ?

2) Or is it that a Galilean analysis is a good approximation of LET when

it comes to compare the theoretical predictions with the experimental

results of light Sagnac experiments ?

3) But then what about the experiments made with massive particles for

which this Galilean analysis is completely wrong ? How do you treat this

case ?

> Now, unfortunately, the following involves physical reasoning, but I'll still

> try. In the Sagnac effect, the Lorentz contraction can be disregarded by

> Lorentzians because there is only one rim and so LC has an equal effect on both

> path lengths. Also, no clock movements or synch procedures need to be made.

> Thus, the Galilean nature of light is clearly recovered in the

> experiment--because there are no relevant deformations of the measuring devices

> to counteract this Galilean nature. And **all** etherists whom I know believe

> in the underlying Galilean nature of light.

Obviously not Lorentz.

> Lorentzians apply the Lorentzian

> corrections only when measuring devices are altered in a relevant way. If not,

> then the Galilean nature is recovered, and as you know, I hope, it takes 3

> lines of algebra to produce Sagnac.

But you end up with a theory which has to treat differently light

propagation, motion of clocks and motion of massive particles around the

rim. On the contrary SR treats all these effects exactly in the same way

and the results can also be derived in a few lines of algebra if one

works in an inertial frame in which the rim is rotating. And more

importantly, this SR treats also with the same tools every experiments

involving inertial frames, and in many cases (all MMX-line experiments),

the result is a mere tautology.

> >But then

> >you are most surely in trouble with Michelson & Morley, Kennedy & Thorndike

> >or Doppler because an Ether theory compatible with these experiments is

> >equivalent to SR as long as we are concerned with observable predictions.

>

> Dennis: That's false. Obviously. IGS theory, for example, fits the known

> experiments. And Lorentz contraction does not need to be assumed.

IGS postulate that the Earth is corotating with a vortex of Ether and

therefore that the speed of a lab on Earth wrt Ether is tiny. But then

you have to assume the consequences of this hypothesis: a vortex around

the Earth corotating with the Moon, a vortex around Saturn corotating

with its satellites. But wait the trajectory of these satellites are not

in the same planes and their periods of rotation are very different. So

does this leads to some observable effects related to the propagation of

the light coming from these objects ? Or do you need one vortex for each

satellite ? Same problem with Jupiter. And what about comets ?

And more importantly where is the complete exhaustive quantitative

comparison of the prediction of IGS with the available relevant

experimental data ? GR and SR predictions and their confrontation to

experiments are reported in hundreds of papers published in widely

available journals. There are even summaries of the current situation,

cf [1] for example. So if you want to convince mainstream science you

have to produce a work with the same quality. Can you do that ?

[1] C.M. Will, gr-qc/9811036 and references therein

Mar 9, 2000, 3:00:00 AM3/9/00

to

>

>

>Dennis McCarthy wrote:

>>

>> >

>> >On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

>> >(in message <20000308124906...@ng-fm1.aol.com>):

>> >

>> >>> This shows clearly that there is much more than a speed anisotropy at

>> >>> work in Sagnac experiments,

>> >>

>> >> Dennis: How on Earth does it show that? Do you still not understand

>that the

>> >> same effect occurs for sound--and for sound clocks?

>> >

>> >What I have explained is treated extensively and precisely in the

>references

>> >I have given. So it is now your turn: please show your math or at least

>some

>> >references to them

>>

>> Dennis: You have given no evidence for your claim above. That's just a

>strange

>> Bourhis conclusion.

>

Bourhis>For the moment I have not seen either Tom Roberts or Steve Carlip>

>Dennis McCarthy wrote:

>>

>> >

>> >On Wed, 8 Mar 2000 17:49:06 +0000, Dennis McCarthy wrote

>> >(in message <20000308124906...@ng-fm1.aol.com>):

>> >

>> >>> This shows clearly that there is much more than a speed anisotropy at

>> >>> work in Sagnac experiments,

>> >>

>> >> Dennis: How on Earth does it show that? Do you still not understand

>that the

>> >> same effect occurs for sound--and for sound clocks?

>> >

>> >What I have explained is treated extensively and precisely in the

>references

>> >I have given. So it is now your turn: please show your math or at least

>some

>> >references to them

>>

>> Dennis: You have given no evidence for your claim above. That's just a

>strange

>> Bourhis conclusion.

>

>contradicting me. Usually they do not hesitate to point out errors in

>whatever messages they are made. Do you think you know better Special

>and General Relativity than all of us ?

Dennis: Forgive me for not being convinced by

proof-by-non-contradiction-by-authority, when my point seems so clear. I'll

repeat it:

Bourhis wrote: ">Now consider two slow moving clocks C+ and C-, respectively

co- and

>counter-rotating. If they are synchronized with a clock at point A, when

>they come back to A, C+ and C- are respectively late and ahead with

>respect to A and the difference between their reading is exactly the

>above time delay T.

>

>This shows clearly that there is much more than a speed anisotropy at

>work in Sagnac experiments, "

Obviously, your argument involving changing clocks cannot rule out the

possibility that speed anisotropy can the cause of the Sagnac effect. This is

true because open-air sound clocks moving around a rotating rim experience the

same effect as described in your premise--and speed anisotropy is what causes

the sound Sagnac.

A cannot entail B when I show an instance where A is true and B is false.

D:>> Also, you gave references for the interesting argument that the length

of

>a

>> rim is not the same CW as CCW for a rim observer. Very strange to say the

>> least.

>

B: >Strange is not by itself a scientific comment.

Dennis: Well, it certainly contradicts what the rim observer measures--as well

as the procedure for determining lengths in all known experiments, including

the one you agreed to.

Bourhis: . This comes from the fact that

>neither the rim nor the light rays are well defined geometrical objects

>entirely embedded in space at a given instant.

Dennis: Ether theories don't have this problem with hypothesizing an

*unobservable* problem with geometrical objects entirely embedded in space at a

given instant.

Bourhis: >This is a definitive result of SR and/or GR, and of course of LET

Dennis: Please stop confusing your idiosyncratic views of a 1904 paper with

ether theories followed today. I have asked you many times to stop this.

B:>Sun-Tzu said : "When involved in a guerilla, launch first the attacks

>which do not cost you anything".

Dennis: I think we should be on an objective search for the truth, not a

guerilla attack.

B:>> >As many people, you consider that defining the length of co- and

>> >counter-rotating light rays or the length of the rim itself is a trivial

>> >question.

>>

>> Dennis: By "A trivial question," Bourhis means using stationary rulers to

>> measure a length of a stationary object. Bourhis feels you can't do that.

>> By "many people", Bourhis means all engineers, scientists, and

>physicsts--who

>> aren't addressing the Sagnac question--*ever* who measure length in the

>normal

>> way.

>

Bourhis: >That is to say in situations where relativistic effects are

completely

>negligeable. That is to say by working with a Galilean framework which

>was indeed a good approximation.

Dennis: Trusting your stationary rulers to measure length of stationary objects

is a "Galilean framework"? And ignoring what you actually measured and going

by theory instead is the relativistic method. Okay, agreed.

D:>> In fact, this was the method of measuring length for Sagnac which

>> **Bourhis himself agreed to** within the last few weeks--before he

>researched

>> the subject--because it's somewhat embarrassing to deny it. And in fact, I

>defy

>> Bourhis to find any experiment in the history of science where length was

>> determined in the way he advocates.

>

Bourhis: >The definition of length used in [4] and precisely explained in [3]

is

>used routinely in GR for a very long time. Moller [5] described it in a

>book published in the 60's and it is therefore even older. It is a very

>general definition because it is equivalent locally to the kind of

>intuitive method you advocate which uses rulers

Dennis: So your desk having a different length CW than CCW is

"intuitive"--despite what you observe, despite what you measure, and despite

the way the rest of the planet measures length?

Bourhis: >Difficulties do only occur when one considers global properties,

Dennis: "Difficulties do only occur" for the theory you advocate. No

"difficulty" occurs for the ether analysis--or for sound Sagnac. And it is

absolutely no problem to measure the distance around a square or circle by

rulers. Engineers, architects, and scientists do it all the time without the

slightest bit of problem at all. The problem only occurs for your theory. So

you have to throw out this obvious measuring method that everyone uses, that is

completely natural, that relies on commonsense definitions of length, and that

you yourself agreed to within the last two weeks--not because engineers or

architects or scientists have a "difficulty" in making the measurement--but

because relativists have a "difficulty" reconciling that obvious measurement

with their theory.

B: And yes this is a new effect

>predicted by Special Relativity and LET but not by Galilean Relativity.

>But how is it possible to be surprised by this fact ?

Dennis: Actually, I would be very surprised to find out that my desk is longer

CW than CCW--as I think most people would. Apparently, you should have been

too because you agreed that it's the same length in both directions two weeks

ago. However, I'm not surprised people are willing to believe that desk is

longer CW than CCW (despite what they measure) in defense of a theory they

advocate.

D: >> It is a length that can only be

>> determined based on theoretical assumptions, i.e., by putting pen to

>paper--and

>> it is a length that *contradicts* what is actually observed by real

>> experimenters using real stationary rulers.

>

B:You are again completely confused. An observer moving infinitely slowly

>along the rim will measure the perimeter:

> L = 2 pi R/(1-(R Omega)^2)^(1/2)

>in units where c=1. But this is not the length of a light ray

>propagating along the rim in the non-inertial frame I have defined

>precisely above. Now how do you propose to measure with rulers the

>length of a light ray ?

Dennis: When you measure the average speed of something that moves from one

point to another (in your frame)--all scientists and engineers measure the

distance between the points (according to your frame) and divide by the time of

travel. I explained this for a week, showing how you glue rulers around the

rim to measure the path. You accepted this incredibly obvious method of

distance measurement that all scientists and all engineers use.

What happened since then?

Do you think it's reasonable to change such reasonable measurement methods

simply because you have since found it that it poses a problem for a theory you

want to advocate?

Don't you think it's more reasonable to abandon the theory--not the universally

accepted and reasonable measurement method?

Dennis McCarthy

Mar 9, 2000, 3:00:00 AM3/9/00

to

>>

>> A clock has nothing to do here - a coincidence indicator does the job. What

>> d'you mean by "the same speed"? D'you postulate it? If so, it's exactly the

>> same unanswered question (2).

>

Berry: >No, our observers measure it. They, for some strange reason, are under

the

>impression that the speeds they measure with their clocks and rulers are

>the actual speeds in their frame.

>

>I suppose _you're_ going to say that their measurements are invalid for

>some reason now, aren't you...

>> A clock has nothing to do here - a coincidence indicator does the job. What

>> d'you mean by "the same speed"? D'you postulate it? If so, it's exactly the

>> same unanswered question (2).

>

Berry: >No, our observers measure it. They, for some strange reason, are under

the

>impression that the speeds they measure with their clocks and rulers are

>the actual speeds in their frame.

>

>I suppose _you're_ going to say that their measurements are invalid for

>some reason now, aren't you...

Dennis: I'm not sure what is meant here. The rim observer using stationary

rulers and a single stationary clock (or just a "coincidence indicator")

clearly measures anisotropy.

It is the relativists who want to argue that the distance measured by the

stationary rulers is actually wrong--and hypothesize that there are

unobservable deformations of the path that make it different CW than CCW.

It would seem to be that if your theory has a difficulty with a well-known

standard, intuitive, logically consistent, universal measurement method--it's

not the measurement method that should be abandoned.

Dennis McCarthy