Why Haven't Two Clocks on a Table Been Used to Measure Light's One-Way Speed?

[Martin Miller]

[DrChinese noted:]
Not so fast.
Same example, add a couple of observers: C in A's frame at -X,
D in B's frame at +X. Now C sees the explosion at a different
time than A & B, as well as D. This is because the times in each
reference frame are different. Besides, even in your example
A & B witness the X explosion occurring at different times because
one of them sees the event before the other (since they are in
relative motion, they will not be co-located at each others' origin).
This effect is called the relativity of simultaneity, because the
only way to get everyone to agree on the timing of events is to have
them share information about each other's reference frames. If this
were not necessary, then we would have absolute simultaneity - which
we don't.
Case closed.

[MM replies:]
Ironically, you just confirmed the temporal portion of my little
experiment, even though no one was quibbling about that.

If you look back at my experiment, you will see that I was
counting on the _times_ being different.

But the _distances_ are the _same_.

Thus, light's speed in each frame was different, contrary to SR.

Case still closed, my way.

 

[DrChinese]

...Thus, light's speed in each frame was different, contrary to SR.

Case still closed, my way.

Why are you on this board if your purpose is to ignore facts? It has been demonstrated to you amply that in your example, it requires the observers to share information about their reference frames to get the anwer you desire. This would not be necessary in a world of absolute time. You are aware that the speed of light is always measured experimentally to be the same in any reference frame, and yet you make statements like the one above.

I would agree the case is closed, your way... because why would I want to waste my time going around in circles on a subject you don't want to learn about? Please enjoy your ego trip and the chance to make statements "your way". Revel in the thought that you are brilliant, and your line of reasoning is original. And by all means, please note that the physics establishment is blind and trying to keep your Nobel-worthy insights from seeing the light of day.

 

[geistkiesel]

Synchronizing clock and veirifation

ahrkron wrote:
"Once you have the two clocks' terminal connected to the same source,
you just send the signal. Each will receive half the current, but
they will start prompted by the same pulse."

There are only two problems with this, namely, you have yet to
prove that the pulses travel at equal speeds wrt the clocks, and
you have yet to provide a means of verifying absolute synchronicity.

And, as I said, but as you seemingly ignored, _if_ you had actually
discovered a means of absolutely synchronizing clocks, then you
would be the first.
[Ref: for some others who have tried, see the following:
"Conventionality in Distant Simultaneity," wherein three
proposals for absolute synch are shot down.
Peter Ohrstrom, Found. Phys. 10, 333 (1978).]

Pardon this abrupt intrusion, but when reading the thread Iwas compelled to respond with the the following regarding synchronicity and verification of same:

Synchronizing clocks
What about the following synchronizing model: Two identical electronic clocks with any necessary resolution, or measured accuaracy, to what ever is level necessary to satisfy the constraints of the problem, are attached to two moving platforms on a steel track that is laser light engineered flat for 2000 km in each direction. The platforms begin to move in opposite directions from each other where the velocities are held constant by identical control pulses to each clock. The instantaneous location is measured within a wavelength of the light photons being emitted simultaneously in the stationary platform. The relativistic implication of length shortening and clock speed dilation are measurably zero at say 1 cm/second for a full journey time of 200,000 seconds for each clock.

Now sending a '0' signal along the attached wire start the clocks ticking. The output channels containing the measured clocks' readings are sent to the origin at regular intervals and both clocks send identical clocktimes in response to a single instance of two pulses directed at both clocks. That the clocks are running at the same speed is demonstrated by their synchronous output measured at the origin.

If this doesn't satisfy synchronicity and verification of the same, then at some instance a photon is directed at both clocks instantaneously from the origin. These photons arrive simultaneously back at the origin to within a wavelength of light after simply reflecting from mirrors on both clock platforms.We even have some calibrating to do perhaps to set the clocks such that the origin is their mutual midpoint. This procedure establishes the exact location of the clocks with respect to the origin which is guaranteed to be located at the midpoint of the clocks.

The fact of the constant velocity of light in what ever frame measured assures us the test photons are moving at the same velocity and travel the same distance in equal durations of flight time. What else is needed, contant temperature housings, correlations of signal during any direction the 4000 km track is pointing, atmospheric conditions minimized, what?

 

[geistkiesel]

Yes, there are a lot of them, aren't there? Which ones have you performed? It's not a question of 'bias', it's a question of results. You're the one proposing that SR is invalid (in some way), I'm challenging you to tell us which of the dozens of experiments which are consistent with SR are, in fact, not. That's precisely what I'm asking* you to do, show us the flaws in the experiments. Experimental or observational results which show this, please!

*For the avoidance of doubt (and at the risk of being painfully repetitious), please look at the experiments on the lists, and for each *you* answer these questions:
1) was a specific prediction from SR made?
2) was that prediction made correctly (e.g. no screw-up in the math)?
3) did the researchers do the experiment/make the observation?
4) were the results consistent with the prediction?

Having done that, please tell us which of the experiments, in your mind, have "NO" as the answer to *any* question.

1) Yes, If an Einstein gedunken experiment described in "Relativity" page 25 - 27 counts as an experiment then I can answer unambiguously Yes to 1). SR through the derived consequences of simultaneity loss predicts such loss for a moving platform that passes the midpoint of two photons emitted simultaneously from A and B with the movng platform located at the midpoint M of A nad B. The moving platform by detecting the light from the B source then the A source is hereby shown to necessitate the discarding of the concept of "simultaneity". The different arrival times lead the observer to conclude the photons were not emitted simultaneously.

2) No the prediciton was not correct.This is not the only possibility the moving observer can intitally make. She could observe that if she were moving the difference in the photons arrival on the moviong platform could result from the motion of the platform. Working backwards http://frontiernet.net/~geistkiesel/index_files/

Basically, the moving platform observer zeros her clock when passing the midpoint and measures t1', the instant the B photon arriives, and t2' the instant the A photon arrives. By making the assumption, to be tested, that she passed the midpoint of two emitted photons at M (where her clocks were zeroed) she ultimatey arrives at an expression t1' = (c-1)/2 = k. Comparing k with the measurd t1' proves simultaneity if t1' = k and one or the other photons was emitted first depending on the difference in t1' and k.

3)It is a gedunken experiment discussed in the literature with some repititon and depth.

4) No, see the link above.

 

[Martin Miller]

[DrChinese declared:]
You are aware that the speed of light is always measured
experimentally to be the same in any reference frame, and
yet you make statements like the one above.

[MM replies:]
Who's wasting whose time?

[MM continues:]
I say you are unless you can back up your above claim
with a date and names re the alleged experiment which
allegedly measured light's one-way speed between two
clocks.

[MM continues:]
Some Chinese doctors can sure cop an attitude.

 

[Martin Miller]

[geistkiesel wrote:]
Synchronizing clocks

What about the following synchronizing model: Two identical
electronic clocks with any necessary resolution, or measured
accuaracy, to what ever is level necessary to satisfy the
constraints of the problem, are attached to two moving platforms...

[MM replies:]
Clocks in different frames will almost certainly run at
different rates, and the difference will matter when
measuring light's speed.

Not to mention the fact that we need the synchronous clocks
to be in a single frame so we can use them to measure light's
one-way speed between them.

Did you know that no one has ever used two clocks in one
frame to measure light's speed? Have you ever wondered
why this is so?

 

[russ_watters]

Did you know that no one has ever used two clocks in one
frame to measure light's speed? Have you ever wondered
why this is so?

It would surprise me if it hasn't been done, but if it hasn't, there's a simple reason: its redundant since both clocks say exactly the same thing.

 

[wisp]

It would surprise me if it hasn't been done, but if it hasn't, there's a simple reason: its redundant since both clocks say exactly the same thing.

Not so, if this test is done by a professional body it will kill off Einstein's SR in one go.
I can't think of anything more embarrassing than to find the fundamental pillar upon which modern physics bases many of its theories, has a dirty great crack in it.
The sooner this experiment is done the better. It is the most important challenge that SR has to face. I hope SR passes, but I think it will prove to be its undoing.

 

[ahrkron]

Physics experiments are currently taking care of much more delicate business. SR has been tested continuously and detailedly since 1905. Despite the wish of many that would like to "uncover the truth about SR", the theory is extremely well established due to its excellent agreement with experiment.

Currently, experimental physics is geared towards much different problems. SR is not an issue anymore. Current efforts have to do with many other aspects of the models we have for nature (CP violation, quark-hadron duality, high temp superconductors, dark matter, supersymmetry, etc.). The type of discrepancies between theory and experiment are clearly not coming from something as basic as SR. If that was the case, the discrepancies would be all over the place, QFT (which is based on SR) would not work, the Standard Model of particle physics wouldn't be able to predict with an 11-digit accuracy, and nobody would be able to hide it.

 

[russ_watters]

Not so, if this test is done by a professional body it will kill off Einstein's SR in one go.
I can't think of anything more embarrassing than to find the fundamental pillar upon which modern physics bases many of its theories, has a dirty great crack in it.
The sooner this experiment is done the better. It is the most important challenge that SR has to face. I hope SR passes, but I think it will prove to be its undoing.

Why would two identical clocks sitting next to each other in the same frame show different times and what would that say about SR (besides 'we need better clocks to test SR...')?

 

[Martin Miller]

[Martin Miller wrote:]
Did you know that no one has ever used two clocks in one
frame to measure light's speed? Have you ever wondered
why this is so?

[russ_watters wrote:]
It would surprise me if it hasn't been done, but if it hasn't,
there's a simple reason: its redundant since both clocks say
exactly the same thing.

[MM replies:]
It has not been done, but not because of your reason; the real
reason is the fact that no physicist knows how to correctly
synchronize clocks.

-------------

[ahrkron declared:]
Physics experiments are currently taking care of much more delicate
business. SR has been tested continuously and detailedly since 1905.

[MM replies:]
Shall this urban legend never die?
Which part of SR has been tested?
Who has tested the basis of SR, namely, the light postulate?

No part of SR is testable because all parts of it are based
100% on a definition.

Every result of SR is a result of Einstein's definition of
synchronization, a mere convention given by man, and having
zilch to do with nature or physics.

For example, SR's "time dilation" or "clock slowing" is
merely an effect of Einstein's definition which relates
clocks incorrectly which in turn causes observers to see
a passing clock "run slow."

Here is how this happens, for those who need pictures:

passing clock
[3]-->
[3]------Frame A------[4]


------------------------[4]-->
[4]------Frame A------[5]

Although all three clocks really run at the same rate,
observers using Einstein's asynchronous clocks "see the
passing clock run slow."

SR per se has nothing to do with actual or real or physical
or intrinsic clock slowing because it does not even know how
to measure it. Also, Einsteinian observers in different frames
find different "rhythms" for the _same_ clock, whereas it is
physically impossible for one clock moving inertially to have
more than one intrinsic rhythm, so we know that SR does not
address or pertain to intrinsic clock rhythms.

And it is impossible to overstate the importance of getting
two clocks correctly related because all two-clock measurements
depend upon this, including light's one-way speed.

 

[russ_watters]

It has not been done, but not because of your reason; the real
reason is the fact that no physicist knows how to correctly
synchronize clocks.

Sorry I asked and I should have guessed - your objections are (of course) based on misunderstandings of the theory and definitions of the terms involved. That your thought experiment is wrong is easily demonstrated by flipping on a GPS receiver.

Synchronizing clocks is trivially easy and is done all the time (quite literally).

 

[Martin Miller]

[russ_watters claimed:]
Synchronizing clocks is trivially easy and is done all the
time (quite literally).

[MM replies:]
So how do the GPS scientists obtain absolute simultaneity
(or absolute synchronization) in violation of Einstein's
relative simultaneity?

(You do not seem to be aware of the fact that the GPS
works not because of synchronous clocks but because of
geometric corrections which can even override the US
military's deliberate data degradation.)

 

[russ_watters]

[russ_watters claimed:]
Synchronizing clocks is trivially easy and is done all the
time (quite literally).

[MM replies:]
So how do the GPS scientists obtain absolute simultaneity
(or absolute synchronization) in violation of Einstein's
relative simultaneity?

(You do not seem to be aware of the fact that the GPS
works not because of synchronous clocks but because of
geometric corrections which can even override the US
military's deliberate data degradation.)

Absolute simultaneity? Who said anything about that? All I said was they synchronize the clocks.

Geometric corrections? You are aware that GPS satellites contain clocks, right? You are aware that the signals sent from the satellites to the recievers are time-coded signals, right? You are aware that the satellite clocks are monitored and corrected by clocks in ground stations, right?

I know you think you're being clever/coy by changing/ignoring definitions and throwing in irrelevant words as if they were important, but it really doesn't help you here: to argue against scientists about a scientific theory, you (whether you like it or not) have to follow their rules. Not following them just makes your arguments look silly.

 

[ahrkron]

Shall this urban legend never die?
Which part of SR has been tested?

Urban legend? now that is funny.

Pretty much all of SR has been thoroughly tested. http://www.weburbia.demon.co.uk/physics/experiments.html has a good compilation of references to serious physics articles about experimental tests of SR.

The following is a quote from that page:

Physics, as a natural science, is based on empirical facts. Physical theories cannot be based just on speculation or suspicion. On the other hand it is always reasonable to have doubts concerning established theories. Reading the posts in sci.physics.relativity I have got the impression, that the huge experimental support for this theory is sometimes not well known. The list of experiments below shows that the SRT is really tested very well. Hypotheses which claim, that SRT is just "wrong" have to show that all the experiments mentioned below had errors or that their interpretation is not correct.

There is a lot of redundancy in these experimental tests. There are also a lot of indirect tests of SRT which are not included in the list shown below. This list of experiments is NOT complete! I cannot guarantee, that the literature list has no mistakes. If I get a positive feedback, I am willing to update the list shown below and to correct all possible errors.

For those seriously concerned about this subject there is an essential new reference book: "Special Relativity and its Experimental Foundation" by Yuan Zhong Zhang, World Scientific (1996).

(the color emphasis is mine)

Who has tested the basis of SR, namely, the light postulate?

Look at section VII in that page.

No part of SR is testable because all parts of it are based 100% on a definition.

Every result of SR is a result of Einstein's definition of
synchronization, a mere convention given by man, and having zilch to do with nature or physics.

"100% definition". Can you point out the what definition you are talking about, and how it affects the measurement of speeds, masses, energies and electromagnetic fields? Please take into account that, when doing an experiment to test SR, the readings are not obtained from SR, but from the actual detectors (which, of course, are not "programmed with SR equations").

 

[wisp]

Pretty much all of SR has been thoroughly tested. this page has a good compilation of references to serious physics articles about experimental tests of SR.

None of these tests compensate for the lack of one-way light speed measurements. The one-way tests that have been done are not accurate enough to prove or disprove SR.
And it is not necessary for all these tests to fail to prove SR false. It only takes one test to fail a theory. Much of the relativistic effects used by SR can be supported by absolute ether theories.
If a one-way test using two clocks shows that the speed of light is not constant because of the motion of the clocks' frame relative to the ether, then relativity is false.

 

[Martin Miller]

[russ_watters asked:]
Absolute simultaneity? Who said anything about that?
All I said was they synchronize the clocks.

[MM replies:]
You did, "dummy." Absolute synchronization is
synonymous with absolute simultaneity, and one
would assume that your "synchronize the clocks"
means "absolutely synchronize the clocks," or
else, why bother.

This conversation has obviously reached its
limits; you merely assert unsubstantiated stuff
over and over, whilst completely ignoring any
and all challenges such as "How can two clocks
be correctly related?" and "How do the GPS folk
actually absolutely synchronize clocks?"

BTW, I think that if you really dig into the GPS
system, you will soon find that even their clocks
are related per Einstein's definition of clock
synchronization, a definition that merely dictates
one-way light speed invariance/isotropy. (This has
to be true because there is no other definition of
synchronization available, sir.)

 

[Martin Miller]

[ahrkron wrote:]

Originally Posted by Martin Miller
Who has tested the basis of SR, namely,
the light postulate?

Look at section VII in that page.

[MM replies:]
It is you who needs to look at Section VII because
that section says zilch about light's one-way speed
between two clocks. (All it talks about is the fact
of light's source-independent nature.)

If you are silly enough to still insist that Sect VII
pertains to light's one-way speed per two clocks, then
please let us know how the clocks were synchronized.

Quote:
No part of SR is testable because all parts of it are based
100% on a definition.
Every result of SR is a result of Einstein's definition of
synchronization, a mere convention given by man, and having
zilch to do with nature or physics.

"100% definition". Can you point out the what definition you
are talking about, and how it affects the measurement of speeds,
masses, energies and electromagnetic fields? Please take into
account that, when doing an experiment to test SR, the readings
are not obtained from SR, but from the actual detectors (which,
of course, are not "programmed with SR equations").

[MM replies:]
'Round and 'round we go, where we'll stop, no one knows.

And here you are trying to discuss SR sans a knowledge of
its basis, Einstein's definition of clock synchronization.

And you are wrong about the "detectors" not being programmed
with SR equations -- the only detectors used in SR are clocks,
and every clock has been related to every other clock (in any
given frame) by Einstein's definition, a convention given only
by man, and which dictates one-way invariance/isotropy.

That is how the programming affects the speed of electromagnetic
fields which are moving through space (i.e., light waves).

And here is how this programming affects all other two-clock
**speed** measurements in SR:

[1] Since Einstein's clocks are asynchronous, all two-clock
measurements in SR are incorrect.
[2] Since Einstein's clock are forced by mere definition from
man to obtain c in all frames for light no matter how a frame
may move through space, the two-clock speeds of any other rapidly-
moving entities are distorted downward.

And here is how this programming affects all two-clock
**mass** measurements in SR:

Since the only tools (or instruments) in SR are clocks and
rods, all mass measurements must involve clocks and rods, and
therefore all mass measurements are incorrect due to the
asynchronousness of Einstein's clocks. For example, despite
the simple and obvious fact that a given object moving at
a single velocity cannot have more than one physical mass,
SR observers in different frames find _different_ masses for
one and the same passing object. This proves that SR does not
pertain to intrinsic or actual masses.

And here is how this programming causes **time dilation**
in SR:

passing clock
[3]-->
[3]------Frame A------[4]


------------------------[4]-->
[4]------Frame A------[5]

Although all three clocks really run at the same rate,
observers using Einstein's asynchronous clocks "see the
passing clock run slow."

SR per se has nothing to do with actual or real or physical
or intrinsic clock slowing because it does not even know how
to measure it. Also, Einsteinian observers in different frames
find different "rhythms" for the _same_ clock, whereas it is
physically impossible for one clock moving inertially to have
more than one intrinsic rhythm, so we know that SR does not
address or pertain to intrinsic clock rhythms.

Any more questions from the unknowledgeable?

 

[ahrkron]

Let me recap:

Martin Miller asked:

Who has tested the basis of SR, namely, the light postulate?

To which I said:

Look at section VII in that page.

Then, his answer is

It is you who needs to look at Section VII because that section says zilch about light's one-way speed between two clocks. (All it talks about is the fact of light's source-independent nature.)

i.e, you accept (in blue) that the site talks about light's source-independent nature. Your not having posted anything on that respect seems to imply that you either have no problem with that part, that you cannot deny the experimental support showed in the articles referred to in that page, or that you concede the point.

Now, you need to make clear for us what is the connection between the light postulate (which is well supported experimentally, as you seemingly accepted), and your idea of "light's one-way speed between two clocks".

You need to do so in a way that does not contradict the experiments reported in that page. And, of course, that does not mean just the little mention on the webpage, but the actual peer-reviewed articles.

I'm not able to do much this weekend, but I'll try to look for the articles later on the week. If I find them, I'll try to post at least the abstracts, so we can make this a real discussion.

 

[Martin Miller]

[ahrkron wrote:]
Now, you need to make clear for us what is the connection between
the light postulate (which is well supported experimentally, as you
seemingly accepted), and your idea of "light's one-way speed between
two clocks".

You need to do so in a way that does not contradict the experiments
reported in that page. And, of course, that does not mean just the
little mention on the webpage, but the actual peer-reviewed articles.

[MM replies:]
The problem here is the fact that you are confused re Einstein's
light postulate.

The following site contains the following definition:
http://www.physics.cornell.edu/courses/p101-102/p102/16/concepts/

The Speed of Light Postulate
"The speed of light in vacuum, measured in any inertial reference frame,
always has the same value of c, no matter how fast the source of light
and the observer are moving relative to each other."

Did you notice the key word "measured"?

It means "measured by using two clocks."
(We don't need a postulate for light's round-trip, one-clock speed
because it has long been c per direct experiment, but, as I have
said, there has been no corresponding one-way experiment.)

In other words, Einstein's light postulate does not pertain to the
source-independency of light, but to the measured one-way speed of
light per two clocks in any given frame.

Do you see the light now?

 

[Nereid]

1) Yes, If an Einstein gedunken experiment described in "Relativity" page 25 - 27 counts as an experiment then I can answer unambiguously Yes to 1). SR through the derived consequences of simultaneity loss predicts such loss for a moving platform that passes the midpoint of two photons emitted simultaneously from A and B with the movng platform located at the midpoint M of A nad B. The moving platform by detecting the light from the B source then the A source is hereby shown to necessitate the discarding of the concept of "simultaneity". The different arrival times lead the observer to conclude the photons were not emitted simultaneously.

2) No the prediciton was not correct.This is not the only possibility the moving observer can intitally make. She could observe that if she were moving the difference in the photons arrival on the moviong platform could result from the motion of the platform. Working backwards http://frontiernet.net/~geistkiesel/index_files/

Basically, the moving platform observer zeros her clock when passing the midpoint and measures t1', the instant the B photon arriives, and t2' the instant the A photon arrives. By making the assumption, to be tested, that she passed the midpoint of two emitted photons at M (where her clocks were zeroed) she ultimatey arrives at an expression t1' = (c-1)/2 = k. Comparing k with the measurd t1' proves simultaneity if t1' = k and one or the other photons was emitted first depending on the difference in t1' and k.

3)It is a gedunken experiment discussed in the literature with some repititon and depth.

4) No, see the link above.

Perhaps I should have been more clear; 'experiments' refers to real experiments, not 'gedunken's.

Thought experiments play a useful role in the development of a new idea; they can bring potential inconsistencies into sharp focus (so the folk developing the theories can make refinements, or scrap the theory), and they can suggest experiments which, if carried out, should yield a clear result - either consistency with the theory, or inconsistency.

However, by and in themselves, thought experiments don't tell you anything about the real world; only stuff done in a lab - with equipment - or the field - with detectors etc - can test an idea or theory.

So, can you provide details of an experiment - done in a lab, in the field, or with telescopes (etc) - whose results are inconsistent with SR?

Perhaps an example by contrast would help: "Are there any experiments - done in a lag, in the field, or with telescopes (etc) - whose results are inconsistent with the Newtonian theory of gravity?" The answer is, of course, yes! Dozens and dozens of them, from the advance of the perihelion of Mercury, to the bending of EM by the Sun's mass (and the Shapiro effect) as observed recently with the Cassini spaceprobe, to observations of binary pulsars.

 

[loseyourname]

It means "measured by using two clocks."
(We don't need a postulate for light's round-trip, one-clock speed
because it has long been c per direct experiment, but, as I have
said, there has been no corresponding one-way experiment.)

In other words, Einstein's light postulate does not pertain to the
source-independency of light, but to the measured one-way speed of
light per two clocks in any given frame.

Do you see the light now?

What you are proposing isn't possible. Even in principle, there is no way to measure the one-way speed of light using only one clock. The constancy of the speed of light is the reason we get the Lorentz coordinate transformations rather than Galilean transformations, which assume absolute time and a variable speed of light. Therefore, any experiment that confirms the Lorentz transformations confirms the absolute nature of the speed of light and hence confirms SR. I'm aware that there exist other explanations given, but SR is the parsimonious theory.

 

[reilly]

SR Test

Nereid noted:
"Einstein's theories ... have been tested in the
crucible of experiment and observation, and have
passed with flying colours."

Sorry to burst your bubble, "Mr. Nereid," but as
far as Einstein's special relativity goes, your
above is purely an urban legend.

There have been exactly zero tests of SR.
***************
You must be joking.

We must live in alternate universes. SR is tested, for example in every high energy particle experiment-relativistic kinematics, using momentum and enrgy rather than space and time- has yet to be found wanting, and it is as basic as it gets in much of today's physics. The Dirac equation, QED, the Standard Theory all SR based, do pretty well, and all are key to today's physics. Why even radar can help test SR. SR is used in the design of accelerators. The arguments are ultimately "preponderance of evidence arguments", and for SR this means many thousands of experiments.

Also be aware that the various arguments/discussions of clocks, measuring rods, time dilation and so forth are simply designed to help make the math more understandable. The verbal arguments can, if not handled with care, lead to problems. The math of SR is as close to perfect as theory can be. You want to discredit SR, go for the hard stuff, like particle physics. Like, show that the Thomas Precession is fake, or something like that.

If this is all an urban myth, then most physicists live in a huge city.

Reilly Atkinson

 

[geistkiesel]

Perhaps I should have been more clear; 'experiments' refers to real experiments, not 'gedunken's.

Thought experiments play a useful role in the development of a new idea; they can bring potential inconsistencies into sharp focus (so the folk developing the theories can make refinements, or scrap the theory), and they can suggest experiments which, if carried out, should yield a clear result - either consistency with the theory, or inconsistency.

However, by and in themselves, thought experiments don't tell you anything about the real world; only stuff done in a lab - with equipment - or the field - with detectors etc - can test an idea or theory.

So, can you provide details of an experiment - done in a lab, in the field, or with telescopes (etc) - whose results are inconsistent with SR?

Perhaps an example by contrast would help: "Are there any experiments - done in a lag, in the field, or with telescopes (etc) - whose results are inconsistent with the Newtonian theory of gravity?" The answer is, of course, yes! Dozens and dozens of them, from the advance of the perihelion of Mercury, to the bending of EM by the Sun's mass (and the Shapiro effect) as observed recently with the Cassini spaceprobe, to observations of binary pulsars.

If there is a consistently generated flaw in SR then SR will be SR whatever and however tested. I will suggest you look at Groubnded's thread for some up to date informtion. Also, if Eibnsteing proposes a Gebndunken, you cannot complain because others discuss that gedunken can you?

Try this one for size: Virtually all experiments discussed where there is a stationary platform and a moving platform make a huge error ion logic. Stationary means stationary, ie. v = 0. Therefiore, when making a conmparison with a moving frame and there is the ineviable claim that each frame is equivalent such that the moving and styationary frames can be exchanged, is physically inpossible to do. Again, "stationary frame" means v = 0, or said in other words, the stationary frame is assumed as an absolute v = 0, from which all measurements are ultimately measured.
-----------------------------------------------------------------------
All moving frame values are non-primed with the exception of M’, the consistent location of the observer O in the moving frame.

At no time is there an inference that M’ was at the midpoint of the A and B photons emitted in the stationary frame.

To demonstrate the following:

Einstein’s moving train calculation indicating when the oncoming B photon is detected at t1 the A photon was located at a position consistent with –t1. Said in other words, as t1 is determined from t0 which locates M’ at t0, the A and B were equidistant to M’(t0) when t = t1.

Proof:
A moving observer located at M’ on a moving frame passes through the midpoint M of photon sources located at A and B in the stationary frame just as A and B emit photons. M’ is moving along a line connecting A and B, toward B.

At this instant the moving source t = t0. Later the moving observer detects the photon from B at t1, and later the photon from A at t2. The observer has measured her velocity wrt the stationary frame as v. Determine the position of the A photon at tx in terms of t0, t1, t2, and v when the B photon was detected at t1.

The photon from A must reach the position of M’ when t = t2. Therefore, the distance traveled by the A photon during Δt = t2 – t1, is Δtc. This is equal to the distance cΔt = vΔt + vt1 + vtx . Now we rearrange somewhat to arrive at, vtx = vΔt – cΔt + –vt1. Now as vΔt - cΔt is just -vtx - vt1

vtx = -vtx - vt1 – vt1

2tx = -2t1

tx = -t1

Therefore, in the moving frame the photon from A and the photon from B were equidistant from M’(t0) at t1.

 

[geistkiesel]

[ahrkron wrote:]

Originally Posted by Martin Miller
Who has tested the basis of SR, namely,
the light postulate?

Look at section VII in that page.

[MM replies:]
It is you who needs to look at Section VII because
that section says zilch about light's one-way speed
between two clocks. (All it talks about is the fact
of light's source-independent nature.)

If you are silly enough to still insist that Sect VII
pertains to light's one-way speed per two clocks, then
please let us know how the clocks were synchronized.

Quote:
No part of SR is testable because all parts of it are based
100% on a definition.
Every result of SR is a result of Einstein's definition of
synchronization, a mere convention given by man, and having
zilch to do with nature or physics.

"100% definition". Can you point out the what definition you
are talking about, and how it affects the measurement of speeds,
masses, energies and electromagnetic fields? Please take into
account that, when doing an experiment to test SR, the readings
are not obtained from SR, but from the actual detectors (which,
of course, are not "programmed with SR equations").

[MM replies:]
'Round and 'round we go, where we'll stop, no one knows.

And here you are trying to discuss SR sans a knowledge of
its basis, Einstein's definition of clock synchronization.

And you are wrong about the "detectors" not being programmed
with SR equations -- the only detectors used in SR are clocks,
and every clock has been related to every other clock (in any
given frame) by Einstein's definition, a convention given only
by man, and which dictates one-way invariance/isotropy.

That is how the programming affects the speed of electromagnetic
fields which are moving through space (i.e., light waves).

And here is how this programming affects all other two-clock
**speed** measurements in SR:

[1] Since Einstein's clocks are asynchronous, all two-clock
measurements in SR are incorrect.
[2] Since Einstein's clock are forced by mere definition from
man to obtain c in all frames for light no matter how a frame
may move through space, the two-clock speeds of any other rapidly-
moving entities are distorted downward.

And here is how this programming affects all two-clock
**mass** measurements in SR:

Since the only tools (or instruments) in SR are clocks and
rods, all mass measurements must involve clocks and rods, and
therefore all mass measurements are incorrect due to the
asynchronousness of Einstein's clocks. For example, despite
the simple and obvious fact that a given object moving at
a single velocity cannot have more than one physical mass,
SR observers in different frames find _different_ masses for
one and the same passing object. This proves that SR does not
pertain to intrinsic or actual masses.

And here is how this programming causes **time dilation**
in SR:

passing clock
[3]-->
[3]------Frame A------[4]


------------------------[4]-->
[4]------Frame A------[5]

Although all three clocks really run at the same rate,
observers using Einstein's asynchronous clocks "see the
passing clock run slow."

SR per se has nothing to do with actual or real or physical
or intrinsic clock slowing because it does not even know how
to measure it. Also, Einsteinian observers in different frames
find different "rhythms" for the _same_ clock, whereas it is
physically impossible for one clock moving inertially to have
more than one intrinsic rhythm, so we know that SR does not
address or pertain to intrinsic clock rhythms.

Any more questions from the unknowledgeable?

Martin Miller: I thought you would be interested in the following regarding SR and simultaneity. It is the Einstein train experiment, looked at slightly differently.

All moving frame values are non-primed with the exception of M’, the consistent location of the observer O in the moving frame.

At no time is there an inference that M’ was at the midpoint of the A and B photons emitted in the stationary frame.

To demonstrate the following:

Einstein’s moving train calculation indicating when the oncoming B photon is detected at t1 the A photon was located at a position consistent with –t1. Said in other words, as t1 is determined from t0 which locates M’ at t0, the A and B were equidistant to M’(t0) when t = t1.

Proof:
A moving observer located at M’ on a moving frame passes through the midpoint M of photon sources located at A and B in the stationary frame just as A and B emit photons. M’ is moving along a line connecting A and B, toward B.

At this instant the moving source t = t0. Later the moving observer detects the photon from B at t1, and later the photon from A at t2. The observer has measured her velocity wrt the stationary frame as v. Determine the position of the A photon at tx in terms of t0, t1, t2, and v when the B photon was detected at t1.

The photon from A must reach the position of M’ when t = t2. Therefore, the distance traveled by the A photon during Δt = t2 – t1, is Δtc. This is equal to the distance cΔt = vΔt + vt1 + vtx . Now we rearrange somewhat to arrive at, vtx = vΔt – cΔt + –vt1. Now as vΔt - cΔt is just -vtx - vt1

vtx = -vtx - vt1 – vt1

2tx = -2t1

tx = -t1

Therefore, in the moving frame the photon from A and the photon from B were equidistant from M’(t0) at t1.

 

[Nereid]

If there is a consistently generated flaw in SR then SR will be SR whatever and however tested. I will suggest you look at Groubnded's thread for some up to date informtion.

Er, um, ... I'm not really following this ... if leseiktsieg proposes that, for masses of 1g to 10^30 g, and distances of 1mm to 10^15 mm, the gravitational force between two masses goes as the inverse cube of the distance between their respective centres of mass, it's pretty easy to test that proposal. Similarly, if SR predicts that pions' observed decay rate will have a certain dependency on their observed speed, it's quite easy to test.

In both cases the experiments and observations are what they are, and proposals or theories are either consistent with the observational data, or not.

Also, if Eibnsteing proposes a Gebndunken, you cannot complain because others discuss that gedunken can you?

Einstein may or may not have proposed a gedunken experiment, but a discussion of any such - no matter how interesting or who proposed it - carries no weight whatsoever against real experiments, competently done.

Try this one for size: Virtually all experiments discussed where there is a stationary platform and a moving platform make a huge error ion logic.

Counter (1): as has been shown many times here on PF, and in many books and papers, claims of such 'huge error ion logic' reflect misunderstanding or SR, misinterpretation, or their own errors.

Counter (2): You take the equations, you plug in the parameters, you crunch the numbers ... and you come up with predictions. You go to the lab, you do the experiments, you get the data. Compare predictions with data, and what do you find? Consistency.

 

[geistkiesel]

Perhaps I should have been more clear; 'experiments' refers to real experiments, not 'gedunken's.

Thought experiments play a useful role in the development of a new idea; they can bring potential inconsistencies into sharp focus (so the folk developing the theories can make refinements, or scrap the theory), and they can suggest experiments which, if carried out, should yield a clear result - either consistency with the theory, or inconsistency.

However, by and in themselves, thought experiments don't tell you anything about the real world; only stuff done in a lab - with equipment - or the field - with detectors etc - can test an idea or theory.

So, can you provide details of an experiment - done in a lab, in the field, or with telescopes (etc) - whose results are inconsistent with SR?

Perhaps an example by contrast would help: "Are there any experiments - done in a lag, in the field, or with telescopes (etc) - whose results are inconsistent with the Newtonian theory of gravity?" The answer is, of course, yes! Dozens and dozens of them, from the advance of the perihelion of Mercury, to the bending of EM by the Sun's mass (and the Shapiro effect) as observed recently with the Cassini spaceprobe, to observations of binary pulsars.

I do not deny your experimental results, I deny the propriety of the way the speed of light is determined, the wave length, the frequency. Your error is consistent.

No theory is set in concrete. All theories must end. Prepare yourself for the inevitable.

 

[Nereid]

I do not deny your experimental results, I deny the propriety of the way the speed of light is determined, the wave length, the frequency. Your error is consistent.

No theory is set in concrete. All theories must end. Prepare yourself for the inevitable.

So how do you propose that the wavelength and frequency of EM radiation be determined?

Please try to be a specific as possible, highlighting differences between the methods used in the lab and field today.

 

[geistkiesel]

So how do you propose that the wavelength and frequency of EM radiation be determined?

Please try to be a specific as possible, highlighting differences between the methods used in the lab and field today.

I suggest you look at Grounded's thread. It takes a while to go from "essay" to the nitty gritty", but in outline it goes like this. In measuring frequency one counts the number of full wave length segments passing through the eye/sec.
There is no denying doppler effects, but one should not consider that moving againt the incoming photon stream compresses the wave lenth, nor does movong away from the photon stream stretch the wavelength.

Using de Sitter's finding that the speed of light is not a funcion of the velocity of the sources one can measure one's speed realative to the the speed of light, which is constant;

relative velocity(to source) is fL - c
where f is the frequency and L the wave length.

measuirng frequency (c + V(observed rel to source))/L

L (relative to the universe) V (obs wrt source)/ f (measured)

Change in frequency = (distance per second relative to source)/L

b3efore you come unglued by this you must look at Grounded's thread. If nothing else you will admit it is uniques and cleverly devised. SR suffers tremendously in its agonizing process of extinguishment.

Absolutes take on a real meaning.

 

[geistkiesel]

So how do you propose that the wavelength and frequency of EM radiation be determined?

Please try to be a specific as possible, highlighting differences between the methods used in the lab and field today.

I suggest you look at Grounded's thread. It takes a while to go from "essay" to the nitty gritty", but in outline it goes like this. In measuring frequency one counts the number of full wave length segments passing through the eye/sec.
There is no denying doppler effects, but one should not consider that moving againt the incoming photon stream compresses the wave length, nor does movong away from the photon stream stretch the wavelength.

Using de Sitter's finding that the speed of light is not a funcion of the velocity of the sources one can measure one's speed realative to the the speed of light, which is constant; Again, i am echoing Grounded without as firm a grasp as zI would like, so don't go ballistic until you too have a "grasp" OK?

relative velocity(to source) is fL - c
where f is the frequency and L the wave length.

measuirng frequency (c + V(observed rel to source))/L

L (relative to the universe) V (obs wrt source)/ f (measured)

Change in frequency = (distance per second relative to source)/L

b3efore you come unglued by this you must look at Grounded's thread. If nothing else you will admit it is uniques and cleverly devised. SR suffers tremendously in its agonizing process of extinguishment.

Absolutes take on a real meaning. I know, heresy, at its worst.
____________________________________________

And while we are on the subject of 'possible contradictions' here is a simple Einstein moving train scenario for your calculations. The moving observer O located at M' in the moving frame passes through M the midpoint of photon sources at A and B just as the sources emit photons. SR predicts the moving frame will not determeine the emitted photons were simultaneous in the moving frame.

So here is the problem:

All moving frame values are non-primed with the exception of M’, the consistent location of the observer O in the moving frame.

At no time is there an inference that M’ was the midpoint of the A and B photons emitted in the stationary frame.

To demonstrate the following:

A_______A_?_______M______|B_____|A________B
                  t0     t1     t2

Whee the moving frame is below the line and all points noted by time (referenced in the moving frame) also indicate the location of M' , the observer. So at t0 M' was colocated with M the midpoint of the emitted photons in the stationary frame.

Einstein’s moving train calculation indicating when the oncoming B photon is detected at t1 the A photon was located at a position consistent with –t1. Said in other words, as t1 is determined from t0 which locates M’ at t0, the A and B were equidistant to M’(t0) when t = t1.

Proof:
A moving observer located at M’ on a moving frame passes through the midpoint M of photon sources located at A and B in the stationary frame just as A and B emit photons. M’ is moving along a line connecting A and B, toward B.

At this instant the moving source t = t0. Later the moving observer detects the photon from B at t1, and later the photon from A at t2. The observer has measured her velocity wrt the stationary frame as v. Determine the position of the A photon at tx in terms of t0, t1, t2, and v when the B photon was detected at t1.

The photon from A must reach the position of M’ when t = t2. Therefore, the distance traveled by the A photon during Δt = t2 – t1, is Δtc. This is equal to the distance cΔt = vΔt + vt1 + vtx . Now we rearrange somewhat to arrive at, vtx = vΔt – cΔt + –vt1. Now as vΔt - cΔt is just -vtx - vt1

vtx = -vtx - vt1 – vt1

2tx = -2t1

tx = -t1

Therefore, in the moving frame the photon from A and the photon from B were equidistant from M’(t0) at t1.

 

[Nereid]

I suggest you look at Grounded's thread. It takes a while to go from "essay" to the nitty gritty", but in outline it goes like this. In measuring frequency one counts the number of full wave length segments passing through the eye/sec.

How does one 'count the number of full wave length segments passing through the eye/sec.'?

 

[geistkiesel]

How does one 'count the number of full wave length segments passing through the eye/sec.'?

Whatever the device that detects the wave as you are heading into it, each complete wave length that passes through the eye, or detector, is a wave length. Grounded makes the point that the reason the wave length seems to change and hence the .constant speed of light measurment which is obvious,, is the failure to account for the speed of the 'eye'., which is neglected in SR theory. The number of these complete wave lengths per second passing through a point would be the frequency.Using Maxwells equations where the product of frequency and wavelength always calculates to c we neglect the observers relative velocity. Adding the detectors velocty the wavelength do not change when "detected".

Doppler shifts are not a compressing of the wave length when moving against the stream.

Grounded has a very lucid post where he uses the analogy of relative velocity of two automobiles. If the observer determines a car passes by at 80.66 ft/sec and the car will pass by in 1/4 of a second the length of the car is 20.1 ft. Now if you go 14.6 ft/sec in the opposite direction our relative speed is 95.32 ft/sec., by adding the 80.66 and the 14.6 ft/sec.

Lets see what happens when we leave out the relative velocity of the observer. 80.66ft/sec with a frequency of 4.7 cars per second we get each car length of 17.1, which we know is wrong. Adding the 14.6/4.7 or 3.1. to the 17.1 we get the proper length of the automobiles.
Ciao

 

[Nereid]

I had a read of quite a few of the posts on this topic, esp by you and Grounded. My conclusion is that, if you are seeking to understand SR and the nature of light (and fully understand how and why Grounded's posts miss the mark*), you may find the best approach is to sign up for a Physics course delivered by a good teacher. Next best would be an online physics course, and third a good textbook.

The challenge, as I see it from the posts, is that this medium of learning (Physics Forums) isn't really working for you two; you need to interact with a good teacher in a richer setting - blackboard/real-time/etc.

Perhaps some PF members could recommend good courses/teachers? textbooks?

Good luck!

*this is not to say that Tom et al haven't done a good job of trying; they obviously know their stuff and their explanations seem clear and cogent to me.

 

[Doc Al]

geistkiesel's "train gedanken" redux

Since geistkiesel has been inspired to repeatedly share his analysis of the Einstein train gedanken experiment (in several threads, mind you) it may bear yet another comment.

And while we are on the subject of 'possible contradictions' here is a simple Einstein moving train scenario for your calculations. The moving observer O located at M' in the moving frame passes through M the midpoint of photon sources at A and B just as the sources emit photons. SR predicts the moving frame will not determeine the emitted photons were simultaneous in the moving frame.

So here is the problem:

All moving frame values are non-primed with the exception of M’, the consistent location of the observer O in the moving frame.

At no time is there an inference that M’ was the midpoint of the A and B photons emitted in the stationary frame.

To demonstrate the following:

A_______A_?_______M______|B_____|A________B
                  t0     t1     t2

Note that the picture is a view from the stationary frame's viewpoint showing where geistkiesel thinks the moving observer is when she:

#1: detects a photon from B (what he labels B/t1), and
#2: detects a photon from A (what he labels A/t2)​

Note further that he thinks he's talking about measurements of time (t1 & t2) made by the moving frame--but he's not.

Whee the moving frame is below the line and all points noted by time (referenced in the moving frame) also indicate the location of M' , the observer. So at t0 M' was colocated with M the midpoint of the emitted photons in the stationary frame.

Einstein’s moving train calculation indicating when the oncoming B photon is detected at t1 the A photon was located at a position consistent with –t1. Said in other words, as t1 is determined from t0 which locates M’ at t0, the A and B were equidistant to M’(t0) when t = t1.

Again, he thinks he is going to show something about measurements made in the moving frame. But he really ends up showing (through some oddball calculation) that according to the stationary frame the photons from A and B are equidistant from M at the moment that event #1 occurs. But this is hardly noteworthy--since, in the stationary frame, the photons are emitted simultaneously and start out equidistant from the midpoint, thus they are always equidistant from the midpoint.

Proof:
A moving observer located at M’ on a moving frame passes through the midpoint M of photon sources located at A and B in the stationary frame just as A and B emit photons. M’ is moving along a line connecting A and B, toward B.

At this instant the moving source t = t0. Later the moving observer detects the photon from B at t1, and later the photon from A at t2. The observer has measured her velocity wrt the stationary frame as v. Determine the position of the A photon at tx in terms of t0, t1, t2, and v when the B photon was detected at t1.

Note again that he thinks he's using times measured in the moving frame, but when you see what he actually does with those times you'll realize that they must be times measured in the stationary frame.

The photon from A must reach the position of M’ when t = t2. Therefore, the distance traveled by the A photon during Δt = t2 – t1, is Δtc. This is equal to the distance cΔt = vΔt + vt1 + vtx . Now we rearrange somewhat to arrive at, vtx = vΔt – cΔt + –vt1. Now as vΔt - cΔt is just -vtx - vt1

vtx = -vtx - vt1 – vt1

2tx = -2t1

tx = -t1

Therefore, in the moving frame the photon from A and the photon from B were equidistant from M’(t0) at t1.

Now that's quite a piece of analysis. If it seems convoluted, it's because geistkiesel thinks he's doing something special with times measured in the moving frame (t2 - t1). But all he's doing is taking an oddball approach to "proving" what should have been obvious: Yes, as seen in the stationary frame the photons from A and B are always equidistant from the midpoint.

 

[Martin Miller]

[Reilly Atkinson wrote:]

[Martin Miller wrote:]
"Einstein's theories ... have been tested in the
crucible of experiment and observation, and have
passed with flying colours."

Sorry to burst your bubble, "Mr. Nereid," but as
far as Einstein's special relativity goes, your
above is purely an urban legend.

There have been exactly zero tests of SR.

***************

[Reilly Atkinson replied:]
You must be joking.

We must live in alternate universes. SR is tested, for example in
every high energy particle experiment-relativistic kinematics, using
momentum and enrgy rather than space and time- has yet to be found
wanting, and it is as basic as it gets in much of today's physics.

[MM replies:]
Wrong. SR does not pertain to intrinsic masses, but only to observer-
dependent, point-of-view "masses." If you believe otherwise, then
tell us how SR measures intrinsic masses.

And your missing the mark so badly with your opening gambit does not
bode well for the remainder of your "arsenal."

[but Reilly Atkinson continued anyway:]
The Dirac equation, QED, the Standard Theory all SR based, do pretty
well, and all are key to today's physics. Why even radar can help test
SR. SR is used in the design of accelerators. The arguments are
ultimately "preponderance of evidence arguments", and for SR this means
many thousands of experiments.

[MM replies:]
Wrong again. Since SR says only one thing, namely, one-way light speed
invariance/isotropy, anything that is "SR based" must also say one-way
light speed invariance; however, none of the things which you mentioned
above say that.

(Further explanation: All SR results {usually called "relativistic
effects} depend on measurements made by two or more clocks in each
frame, and, as we all know, all clock pairs in SR are related via
Einstein's definition of clock synchronization, which of course is
Einstein's demand that clocks obtain one-way light speed invariance.)

[Reilly Atkinson continued:]
Also be aware that the various arguments/discussions of clocks,
measuring rods, time dilation and so forth are simply designed to help
make the math more understandable. The verbal arguments can, if not
handled with care, lead to problems. The math of SR is as close to
perfect as theory can be. You want to discredit SR, go for the hard
stuff, like particle physics. Like, show that the Thomas Precession
is fake, or something like that.

[MM replies:]
Wrong once more. SR's math is totally bogus. The times (t and t') of
SR's math are admittedly incorrect due to the lack of absolute clock
synchronization in SR, and the distances (x and x') of SR's math have
not been proved to be correct because no one has shown that rulers
do not physically contract. (In fact, the Michelson-Morley experiment
showed the opposite.)

[Reilly Atkinson continued:]
If this is all an urban myth, then most physicists live in a huge city.

[MM replies:]
You seem to have forgotten that Einstein himself (supposedly) "blew
away" the majority of physicists in his day.

Here is a little math exercise for you, since you seem to think that
math is so great for physics:

It is well known that Einstein's assumption of one-way light speed
invariance/isotropy was the basis of SR. (This is often called his
light postulate.) Your task, should you be bold enough to accept it,
is to show on paper and mathematically exactly how one-way invariance
and isotropy could occur in nature. (I won't be holding my breath!)