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So far there is no known theory/model of the speed of light consistent with all these contradicting evidences. Only experiments with complete null results agree with special relativity.
If I wanted to look into, for example, Silvertooth's work, what would you say is the definitive version of his experimental observation?What's his "best shot" at convincing me?
Quote from: Bored chemist on 28/02/2021 11:12:37If I wanted to look into, for example, Silvertooth's work, what would you say is the definitive version of his experimental observation?What's his "best shot" at convincing me?I have some problem copying the links, but you can easily search on Googlescholar:" Motion through the ether", E.W. Silvertooth, 1989Note that even Silvertooth himself could not give a clear theoretical explanation of the effect he observed, as he acknowledges at the end of his paper.Note also that the Silvertooth experiment has been repeated independently:" A Replication of the Silvettooth Experiment", Doug Marett
Quote from: Hal on 28/02/2021 11:00:36Surprise! There is also an experiment that appears to agree with emission (ballistic) theory, hence disproving both the ether and relativity. This is the Venus planet radar range data anomaly as analyzed by Bryan G Wallace.Has this experiment been verified by other scientists?It should be readily repeatable.
Surprise! There is also an experiment that appears to agree with emission (ballistic) theory, hence disproving both the ether and relativity. This is the Venus planet radar range data anomaly as analyzed by Bryan G Wallace.
Quote from: Hal on 28/02/2021 11:00:36So far there is no known theory/model of the speed of light consistent with all these contradicting evidences. Only experiments with complete null results agree with special relativity.I tend to agree with the last sentence above. Thus in order to convince that special relativity is true, it is necessary to find some sources of discrepancies in those experiments with contradicting results.
A somewhat similar experiment has been performed/analyzed by a NASA scientist. The paper can be found on the arXiv:" Lunar Laser Ranging Test of the Invariance of c " , Daniel Y Gezari
1. INTRODUCTIONWe have measured the two-way speed of light (c) using lunar laser ranging to test theinvariance of c to motion of the observer, a necessary condition for the local Lorentzinvariance of c and the fundamental assumption underlying all of the predictions ofthe special theory of relativity (Einstein 1905) in the matter and photon sectors.Surprisingly, a review of the experimental literature finds no previous publishedreport of an attempt to measure c directly with a moving detector to confirm that lightactually propagates this way (Gezari 2009).
4. PRINCIPLE OF THE CALCULATIONCalculating the speed of light from modeled distance and measured time-of-flightwould seem to be a simple exercise, yet there seems to be no agreement on whatmethod would correctly apply, or how the results should be interpreted. Therefore,we must justify all details of this calculation, regardless how obvious or trivial theymight be.In general, we claim that the calculated speed of a light pulse in some reference frameis simply the distance the pulse travels in that frame from source to detector, dividedby the time-of-flight of the pulse over that distance. The observatory (O) is movingalong the line-of-sight at some speed vO in the local Earth-center/Moon-centerstationary frame (S) due to the rotation of the Earth. The emitted light pulse reachesthe detector after some elapsed time T measured directly by the observer in frame O.The observer makes only one time-of-flight measurement, and this single timemeasurement may then be used for whatever speed calculation the observer mightmake, be it the speed of the pulse in frame O, in frame S, or in any other frame. Butthe optical path lengths are different in frame O and frame S when the observatory ismoving (discussed in Section 2.3), and these lengths must be utilized appropriately.
6. DISCUSSIONIn familiar test theories of special relativity (e.g., Mansouri and Sexl 1977) the observedspeed of light is expressed as cO = c ± kvO where vO is the velocity of the observer alongthe line-of-sight in the local stationary frame, and the coefficient k has the value k = 1for classical relativity and k = 0 for special relativity. For the result obtained here wefind k = 0.95 ± 0.05. The observed speed of light measured by an observer moving atspeed vO seems to follow the simple relation cO = c ± vO. This result is notincompatible with nor does it preclude the idea that the speed of light itself isconstant and invariant, or that light always propagates in free space at some uniquespeed, perhaps even at the nominal value c = 299,792,458 m/s. But it does imply thatlight travels at that unique speed only in one preferred or absolute reference frame.An observer moving relative to that preferred frame would measure the speed of lightto be other than the nominal value.
7. CONCLUSIONThe most straightforward analysis and interpretation of two-way lunar laser rangingmeasurement of c presented here suggests that light propagating between the Earthand the Moon obeys a classical rather than special relativistic addition of velocities law.On the face of it, this constitutes a first-order violation of local Lorentz invariance andimplies that light propagates in an absolute reference frame, a conclusion that mostphysicists (except perhaps some contemporary field theorists) would be reluctant toaccept. Rather than simply dismiss the present results and conclusions as implausible,which would be natural considering the strength of the prevailing view, it would beprudent to critically re-examine and improve the present experimental basis for specialrelativity in the photon sector. Ultimately, any concerns about the validity of a theorycan only be resolved by experiment. We are now pursuing two new approaches toone-way measurements of the speed of light with slowly moving sources and detectors,both by one-way laser ranging outside the Earth’s atmosphere (Gezari et al. 2010) andby direct optical pulse timing in the laboratory.
Quote from: hamdani yusuf on 28/02/2021 12:46:24Quote from: Hal on 28/02/2021 11:00:36Surprise! There is also an experiment that appears to agree with emission (ballistic) theory, hence disproving both the ether and relativity. This is the Venus planet radar range data anomaly as analyzed by Bryan G Wallace.Has this experiment been verified by other scientists?It should be readily repeatable.A somewhat similar experiment has been performed/analyzed by a NASA scientist. The paper can be found on the arXiv:" Lunar Laser Ranging Test of the Invariance of c " , Daniel Y Gezari
I had a brief lookThe first thing to note is that it doesn't matter if he's a NASA scientist.The second is the claim; here's the start of the abstract."The speed of laser light pulses launched from Earth and returned by a retro-reflectoron the Moon was calculated from precision round-trip time-of-flight measurements andmodeled distances. The measured speed of light (c) in the moving observer’s rest framewas found to exceed the canonical value c = 299,792,458 m/s by 200±10 m/s, just thespeed of the observatory along the line-of-sight due to the rotation of the Earth duringthe measurements. "So he has calculated the speed of light based on a model of where the Moon is; compared to the laser ranging data.He finds that there's a discrepancy of 200 +/- 10 m/s
It leads you to wonder how come nobody noticed before.Plenty of high precision measurements rely on C being constant. If it wasn't then it would throw up anomalies in other experiments.
It was mentioned in the paper that all high precision measurements of c were done where the distance between source and receiver is constant, i.e. no relative speed.
But my sat nave works.
So the practical experience of lots of people shows that C is actually constant.You might do one experiment- or a dozen.But I can show you ten million experiments that show that C is constant.
No amount of experimentation can ever prove me right; a single experiment can prove me wrong.Albert Einstein
Is it not more realistic to suppose that the model of the moon's location that he used is inaccurate?
I haven't looked into it closely.
QuoteNo amount of experimentation can ever prove me right; a single experiment can prove me wrong.Albert Einstein
That doesn't quite work, does it.If I say these seeds will grow and produce white flowers, and you say they won't then the experiment of growing the seeds and looking at the flowers will prove that one of us is wrong and the other is right.More generally, if an experiment can prove a theory wrong, then that same experiment proves that the theory "that other theory is incorrect" is right.
The first thing to note is that it doesn't matter if he's a NASA scientist.However the measurements of C have been refined over the centuries and we can measure it precisely The value of C was known to 9 digits before they opted to use it as the definition of the metre.So a change of 1.5 parts per million is a huge discrepancy.It leads you to wonder how come nobody noticed before.Plenty of high precision measurements rely on C being constant. If it wasn't then it would throw up anomalies in other experiments.The third, and perhaps biggest, problem is the model.We have a good idea of where the Moon is, and we can model it's behaviour very accurately.But the only reason we can do this is that we measure the distance to it by bouncing light off it, and measuring the round trip time.What that paper says is that the round trip time gives the wrong answer.In which case the model is wrong.In which case you can't use it to measure the round trip time.You end up going in circles here.And finally there's the fundamental idea that we have to decide on which is right: either the speed of light is wrong or the model is wrong.
There is no experiment so far using time of flight method.
Regarding the precisely known speed of light, I think it is the phase velocity that is known with precision.There is no experiment so far using time of flight method.
The radar level transmitter’s working principleWhen the product surface reflects the pulse, the meter receives the reflection. Then the device calculates how long it took the pulse to return and translates that time delay into a level measurement.
Quote from: Hal on 05/03/2021 15:15:55There is no experiment so far using time of flight method.Are you sure?This looks to me like one."Between 1877 and 1931, Albert A. Michelson made multiple measurements of the speed of light. His 1877–79 measurements were performed under the auspices of Simon Newcomb, who was also working on measuring the speed of light. Michelson's setup incorporated several refinements on Foucault's original arrangement. ... He used carefully calibrated tuning forks to monitor the rotation rate of the air-turbine-powered mirror R, and he would typically measure displacements of the slit image on the order of 115 mm.[8] His 1879 figure for the speed of light, 299944±51 km/s, was within about 0.05% of the modern value. His 1926 repeat of the experiment incorporated still further refinements such as the use of polygonal prism-shaped rotating mirrors (enabling a brighter image) having from eight through sixteen facets and a 22 mile baseline surveyed to fractional parts-per-million accuracy. His figure of 299,796±4 km/s[16] was only about 4 km/s higher than the current accepted value."Fromhttps://en.wikipedia.org/wiki/Fizeau%E2%80%93Foucault_apparatus#Michelson's_refinement_of_the_Foucault_experiment
Quote from: Hal on 05/03/2021 15:15:55Regarding the precisely known speed of light, I think it is the phase velocity that is known with precision.There is no experiment so far using time of flight method.There is. I know because I use it as part of my routine job. I'm responsible for instrumentation device selection and supervising their maintenance, including calibrations.QuoteThe radar level transmitter’s working principleWhen the product surface reflects the pulse, the meter receives the reflection. Then the device calculates how long it took the pulse to return and translates that time delay into a level measurement.https://visaya.solutions/en/qa/radar-level-measurementThis sensor type is pretty reliable and precise, and can detect a millimeter distance variation.
Quote from: hamdani yusuf on 02/03/2021 08:21:22I haven't looked into it closely.I'm not sure what needs looking into.You can't model the position of the moon unless you can tell where it is.The only good data we have on the position of the moon is from laser or radar.He's using the model to say that laser ranging can't work.So he is using the constancy of the speed of light to show that the speed of light is not constant.His argument fails by reductio ad absurdum.