Lunar laser ranging test of the invariance of c

[wisp]

IIRC, the light sent out by particles in a particle accelerator has been analyzed. Measurements of the speed of light in both directions (forward resp. reverse relative to the particle's moving direction) confirmed that c= const. These results are very strong arguments against Daniel Gezari ‘s interpretation of his findings.

Unfortunately, I can't find the literature describing these experiments. But I'm sure there are experts here who can tell you more about this.

The experiment I believe had an accuracy of around 0.99975c and this gives an error margin of 75km/s, which is not very accurate.
Gezari’s experiment is dealing with speed accuracies of a few m/s, which is thousands of times more accurate.
These types experiments that support SR seem very crude by comparison.

[wisp]

Hold on there. Where in that paper does Gezari show the exact calculations of the interaction between distance and motion? I'll give you the answer, there are none. He claims he's modeled the combination of distance and motion by (from what I can gather, he isn't really clear on his method) combining the NAIF/SPICE toolkit and the IERS. He's claimed a accuracy of plus or minus 1m which I don't argue. But he doesn't show his full calculations on how exactly he's using the combination of both those sources. Why not? Until he provides his calculations on how he combined the two different scourses, he does not have a exact distance or motion and so doe not have an exact measurement.

I also question several things in his discussion:



There are more than just extended particle half lives that demonstrated time dilation. Also, would you care to explain the underlying physical process of the charge of a electron to me?



Yes, so what? He's cherry-picking and obfuscating. You do know that that equation is a special example of a more general equation, right? The important part of that equation is the general equation, which includes momentum. Gould goes on, in that paper, to explain that whole general equation E² = (mc²)²+(pc)² requires SR.



Well, then you should be able to show the prediction of Ritz's theory explains the inspiral of the binary pulsars, right? Otherwise, Ritz's theory doesn't apply.

To be honest, these three point sounds just like Gezari doesn't like relativity for some reason, more than he can show it to be wrong. I've got a few more, but I'll wait for now.

I think the guys at NASA know what they’re doing when it comes to Lunar Ranging. The distances measured are the most accurate made by mankind.

What do you mean by the interaction between distance and motion?
Light leaves the laser, and the clock records the launch time LT and the modelled distances are noted: DL, DLB, etc.
Light hits the mirror and the motion/distance of the moon relative to the earth-moon centres are noted to great accuracy.
There is a lot of data given - both modelled and measured. This can be analysed in many different ways using classical or SR models.
But the question remains. Why is there a large discrepancy in light’s measured speed of - 8.4 m/s.
And of course the motion of an object does not affect the speed of a photon launching/bouncing/hitting it. So as long as we know the modelled distances, the motion of the object does not transfer onto the photon’s speed.
**
Re:Time Dilation
From SR perspective the underlying physical process of time dilation is not understood. The mathematical relationship that exists between different inertial fames can only mean there can never be a physical process involved. If on the other hand the motion were relative to an absolute ether frame then an underlying physical process could be found. As a body moves relative to the ether absolute frame it would experience time dilation.

[wisp]

The above is aptently false, such experiments have been conducted many times before and falsify Gezari's incorrect experiment. I gave you a boatload of references.

Q2: Prove that "Gerari’s paper is the first accurate direct measurement of light’s speed in free space using a moving detector"

Can you give me one clear experiment that falsifies Gezari’s paper. I’ve looked through the list and can see anything specific?

Ans Q2. The proof is in his paper. Using very accurate time measurement resolutions of 0.1nS, coupled with the most accurate distance measurements ever made by mankind. I would like to see other lunar ranging papers to see if the offset value of -8.4m/s varies.
It doesn’t matter that the motion of the detector cannot be proven to be in motion as with SR it’s always relative. If the motion issue is ignored, why does light travel slower than expected by 8.4m/s! That’s something SR can’t explain, but an absolute ether model could.

Under SR you cannot prove the speed of light is constant. It’s postulated as constant and set accordingly using clocks synchronized Einstein’s way. This is why Gezari is being challenged on his method because it’s against SR thinking. But his experiment is simple - fire a laser at a mirror on the moon and very accurately measure light’s speed by the distance light travelled/time-of-flight. The answer he gets is not c but c-8.4m/s (ignoring the motion of the earth/moon).

[wisp]

There is no "absolute frame".

Q3: Prove that there is one.

Well if light travels at a speed c in an absolute frame. And the earth-moon system is moving through this frame at speed v.
Then the time-of-flight for light to travel between the earth-moon is:
2Lc/(c^2-v ^2) assuming light is travelling parallel to the ether flow.
The slowing of light would be by (v^2)/c.
Lets say v=50km/s
Light would slow by 8.3m/s similar to the figure Gezari found. It could be that the ether flow V (possibly 600km/s) is much larger than this and the direction of the laser light at the time of the experiment was affected by a component (V*cos(theta)) of its value, where theta (85 degrees) is the angle between the ether flow and the laser light. See,
http://muller.lbl.gov/COBE-early_history/SciAm.pdf 4 meg file. Billions of years ago the motion of the CMBR may have been linked with the ether flow direction, but this may have changed over time as a result of local rotations in the ether.
This is not proof the there is an absolute frame but the slower speed of light result does imply it could exist.

[wisp]

He's old but he still made the rookie mistake of taking the closing speed as measured light speed.

He has years of experience in this type of work and is getting criticized for challenging the view that the speed of light in free space is constant. To be expected. All he’s done is published the results of a very accurate experiment. Even ignoring the motion bit the result is definitely not c.

[macaw]

Can you give me one clear experiment that falsifies Gezari’s paper. I’ve looked through the list and can see anything specific?

All experiments measuring light speed from moving sources falsify Gezari's paper.

Ans Q2. The proof is in his paper. Using very accurate time measurement resolutions of 0.1nS, coupled with the most accurate distance measurements ever made by mankind. I would like to see other lunar ranging papers to see if the offset value of -8.4m/s varies.

Gezari is NOT measuring light speed, he's measuring the closing speed.
Do you understand the difference?

It doesn’t matter that the motion of the detector cannot be proven to be in motion as with SR it’s always relative. If the motion issue is ignored, why does light travel slower than expected by 8.4m/s!

Light does not travel slower, his formula measures c-v, where v is the receding speed of the reflector.

That’s something SR can’t explain, but an absolute ether model could.

This is something that is elementary in SR, called "closing speed". Gezari doesn't understand it. Neither do you.

Under SR you cannot prove the speed of light is constant.

You cannot prove anything in respect to a theory. The scientific method shows that you can only disprove (falsify) a theory. The way prior experiments falsify Gezari's fringe paper.

It’s postulated as constant and set accordingly using clocks synchronized Einstein’s way. This is why Gezari is being challenged on his method because it’s against SR thinking.

Gezari is being challenged because he doesn't know basic physics. He measured closing speed and he claims he's measured variable light speed. This is a rookie mistake.

But his experiment is simple - fire a laser at a mirror on the moon and very accurately measure light’s speed by the distance light travelled/time-of-flight. The answer he gets is not c but c-8.4m/s (ignoring the motion of the earth/moon).

Q5: What happens if there is relative motion between the moon and the Earth? Show the formulas.

[wisp]

This is wrong, as explained to you it does so, on a daily basis.
Q4: Please explain how GPS can work if the speed of em waves coming from GPS satelittes varied with the relative speed between satelittes and the Earth receptors.

Gezari doesn't understand the basics of SR, even less how GPS works. Please stop using his fringe claims in support of your ATM and answer the questions in your own words.

From your "Tom Roberts" link in #2

“The Global Positioning System (GPS)
While not really an experiment, and not really any sort of test of SR, the GPS is an interesting and useful system in which relativity plays an important part. In particular it has become the best and most economical method of highly accurate time transfer around the globe.”

[macaw]

Well if light travels at a speed c in an absolute frame. And the earth-moon system is moving through this frame at speed v.

Err, no. The moon is moving wrt the Earth at speed v.

Then the time-of-flight for light to travel between the earth-moon is:
2Lc/(c^2-v ^2) assuming light is travelling parallel to the ether flow.

Err, also wrong.

Q6: Derive the above formula. Let's see your derivation.

The slowing of light would be by (v^2)/c.

Wrong again.

Q7: The mon is receding from the Earth at speed v, what is the time for a light beam sent off the Earth to bounce off the reflector located on the moon and to come back to Earth?

Q8: same question for the mon approaching the Earth at speed v.

This is not proof the there is an absolute frame but the slower speed of light result does imply it could exist.

You answer has nothing to do with any "absolute frame".

[macaw]

From your "Tom Roberts" link in #2

“The Global Positioning System (GPS)
While not really an experiment, and not really any sort of test of SR, the GPS is an interesting and useful system in which relativity plays an important part. In particular it has become the best and most economical method of highly accurate time transfer around the globe.”

I asked you not to cut and paste and to give your own answers.
The GPS tracking through trilateration would fail if light speed were variable, as in the Gezari paper. So, you need to go back and answer the challenge at Q4:

Q4: Show how the GPS trilateration would work if light speed were variable. Use your own formulas, please.

[macaw]

Re:Time Dilation
From SR perspective the underlying physical process of time dilation is not understood.

This is false, the process is very well understood (by the people in the mainstream physics).

The mathematical relationship that exists between different inertial fames can only mean there can never be a physical process involved.

Q9: Why would you claim such athing? The time dilation predicted in SR has been measured thruogh many experiments, do you think that measurement is not part of the physical reality?

If on the other hand the motion were relative to an absolute ether frame then an underlying physical process could be found. As a body moves relative to the ether absolute frame it would experience time dilation.

Q10: How does the presence of an aether frame affect the time dilation. Derivethe time dilation equation of your ATM from base principles (the presence of the "aether frame")

[macaw]

The experiment I believe had an accuracy of around 0.99975c and this gives an error margin of 75km/s, which is not very accurate.
Gezari’s experiment is dealing with speed accuracies of a few m/s, which is thousands of times more accurate.
These types experiments that support SR seem very crude by comparison.

This is false, see below:



A free-electron laser (http://vuv-fel.desy.de/.) was used to generate highly collimated X-rays parallel to the relativistic electron beam that is their source. If the region that generates the X-rays is L meters long, and the speed of light emitted from the moving electrons is c+kv (here v is essentially c), then at the downstream end of that region the minimum pulse width is k(L/c)/(1+k), because light emitted at the beginning arrives before light emitted at the downstream end. For FLASH, L=30 meters, v=0.9999997 c (700 MeV), and the observed X-ray pulse width is as short as 25 fs. This puts an upper limit on k of 2.5×10^−7.

Q11: What is 2.5×10^−7 c?

If you look at the link I gave you, the researchers have just upgraded FLASH from 700MeV to 1.2 GeV.

Q12: What is the effect of the increased energy on the increased precision? What is the newly predicted precision?

Oh, btw, look here:

K. Brecher, “Is the Speed of Light Independent of the Velocity of the Source?”, Phys. Rev. Lett. 39 1051–1054, 1236(E) (1977).

Uses observations of binary pulsars to put a limit on the source-velocity dependence of the speed of light. k < 2×10^−9.

Q13: What is 2×10^−9 c?

[AstroRockHunter]

... [SNIP] ... I think the guys at NASA know what they’re doing when it comes to Lunar Ranging. The distances measured are the most accurate made by mankind.

Assuming that this statement is true (and I believe that it is) what makes the measurement so accurate?

To answer my own question, from the fact that NASA, and other institutions, bounced laser light off of reflectors placed on the moon. Now, bouncing laser light off of the moon doesn't, in and of itself, yield the answer magically. What happens is that the round trip of the light is timed very accurately, and that time is multiplied by the speed of light (which is defined as c)!

Since the earth/moon distance is determined in this manner, and the models of the earth/moon distance is based on this procedure, then the next question that needs to be answered is:

Direct Question:

How can one use the same procedure to prove that the speed of light is not constant?

On a lighter note, if the guys at NASA are really that good at this measurment thing, then where did the saying 'guess the units, hit the planet' come from?

[wisp]

We can make a few stabs at it. He says:His results are amazingly regular--which is what attracted me to this problem--in fact, they're so regular, I think we can deal with just a single data point. So, for myself, I chose the first one, from Table 1. You can refer to his Figure 2 (which I've attached below) also--it appears that his Modeled Time-of-Flight T_LB+T_BR is just D_LB+D_BR divided by the speed of light c (299,792458 m/s), or a round-trip time of just over 2.6 seconds.

One thing that jumped out at me was the calculations involving the surface of the earth. He doesn't seem to account for the almost 3000 meter altitude of APO (Apache Point Observatory) nor the oblateness of the earth nor the geodetic character of latitude--but I've convinced myself that none of those would result in the discrepany that he reports. But, the distance from the moon to APO is dependent upon the longitude of APO. Their website gives it as 105° 49' 13" W, which is 254.1797°--not much different from Gazari's value above of 254.18°, but Gazari's value translates into 105° 49' 12" W, a difference of exactly 1". 1" at a latitude of 32° is about 25 meters, or over 50 meters round-trip, which in 2.6 seconds would make a difference of nearly 20m/s, two or three times the result that he seems to be reporting. So, we can't use his published values to check his results.

The figures in his paper - 3. Observations
Just set the scene for observations made. They were made at sunrise at the APO (lat and long were given so you could lookup the station on google earth is you wished). The fact they are rounded up doesn’t make them the same as the ones used by NASA for lunar ranging calculations - Lunar ranging measurements is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to one hundredth of an inch.
I google earthed the figures and it took me straight to the AP observatory.
This has nothing to do with the data used to measure the speed of light in the experiment, which was found to be slower than c by 8.4m/s.

[macaw]

Lunar ranging measurements is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to one hundredth of an inch.

The NASA measurements were made using c=constant. Did you know that?

I google earthed the figures and it took me straight to the AP observatory.
This has nothing to do with the data used to measure the speed of light in the experiment, which was found to be slower than c by 8.4m/s.

Sure, if you are Gezari and you don't know what you are doing and you inadvertenly subtract the separation speed between the moon and the Earth.

[Strange]

From your "Tom Roberts" link in #2

“The Global Positioning System (GPS)
While not really an experiment, and not really any sort of test of SR, the GPS is an interesting and useful system in which relativity plays an important part. In particular it has become the best and most economical method of highly accurate time transfer around the globe.”

Apart from being completely irrelevant to the question asked, that is an almost surreal bit of highlighting. Was it supposed to imply that GPS doesn't use SR? How about the in which relativity plays an important part bit? How many GPS processors have you designed?

[macaw]

Apart from being completely irrelevant to the question asked, that is an almost surreal bit of highlighting. Was it supposed to imply that GPS doesn't use SR? How about the in which relativity plays an important part bit? How many GPS processors have you designed?

Seconded, see here for a detailed explanation.

[grav]

It seems that even a discrepency of ten meters one way would produce that result for the speed of light. I don't see how the distance the light has travelled can be measured so precisely to begin with, except by perhaps using light travelling at c in the first place. If we were to attempt to measure the distance between the Earth and moon through observations of the paths travelled gravitationally, for instance, by using their centers of masses, the gravitational constant is only known to a few digits as well as that of the masses in the same way, and gravity is an incomplete theory as well, so the most we could hope to achieve by that method is a margin of error of about 10^-4. On top of this, we couldn't specify the exact distance from the center of mass of the moon to the mirror or for that on Earth without using light measurement either as far as I know. So as far as I can tell, measuring the speed of light over a distance that is measured using light in the first place is circular, and at best would only serve to reaffirm light speed itself and the preciseness of the measurements taken as the Earth and moon move. It reminds me of when it was attempted to show the speed of gravity at c using the light travelling from Jupiter, when they were really only measuring light speed to begin with. Otherwise, how can the distance between the Earth and moon be determined to such accuracy without using light speed?

[macaw]

It seems that even a discrepency of ten meters one way would produce that result for the speed of light. I don't see how the distance the light has travelled can be measured so precisely to begin with, except by perhaps using light travelling at c in the first place.

Have you read post #42? It answers your question.

[grav]

Have you read post #42? It answers your question.

Ah, so it does.

[macaw]

Ah, so it does.

So, Gezari is using distances Earth-moon derived using the fact that c=constant in order to "prove" that c=variable.
Attaboy! such a "scientist" is not to be found every day :-)

[Geo Kaplan]

S, Gezari is using distances Earth-moon derived using the fact that c=constant in order to "prove" that c=variable.
Attaboy! such a "scientist" is not to be found every day :-)

It will be interesting to see if the journal accepts the paper. It would seem to have some, um, weaknesses.

[macaw]

The figures in his paper - 3. Observations
Just set the scene for observations made. They were made at sunrise at the APO.

The measurements of the Earth-moon distances by NASA are based on c=constant (they really measured to transition times for light).

Q14: How can Gezari justify using aforementioned distances , derived for c=constant, in order to "prove" that c=variable? Do you see the internal contradiction in his paper? It is kind of ironic that Gezari uses the results of a theory (c=constant) in his "derivation", thus contradicting himself. Attaboy!

[macaw]

It will be interesting to see if the journal accepts the paper. It would seem to have some, um, weaknesses.

The journal is not a very good one but I don't think they'll touch the Gezari paper with a 10 foot pole. It is too obviously crank.

[Geo Kaplan]

The journal is not a very good one but I don't think they'll touch the Gezari paper with a 10 foot pole. It is too obviously crank.

If the peer review process works at all, it may be rejected so fast that it Doppler shifts...

[grapes]

Since the Moon and the Earth are in relative motion wrt each other, what Gezari is measuring is their closing speed, i.e. c+v when they are moving towards each other and c-v when they are moving away from each other. This is painfully evident from paragraph 4.2.

Isn't paragraph 4.2 a discussion about what the author thinks should be avoided? I don't see where 4.2 shows that he is actually doing it.

The figures in his paper - 3. Observations
Just set the scene for observations made. They were made at sunrise at the APO (lat and long were given so you could lookup the station on google earth is you wished). The fact they are rounded up doesn’t make them the same as the ones used by NASA for lunar ranging calculations - Lunar ranging measurements is one of the most precise distance measurements ever made, and is equivalent in accuracy to determining the distance between Los Angeles and New York to one hundredth of an inch.
I google earthed the figures and it took me straight to the AP observatory.
This has nothing to do with the data used to measure the speed of light in the experiment, which was found to be slower than c by 8.4m/s.

You might be right, it might have nothing to do with it. I was just using the figures that he mentions in his paper. If he used different figures, then he should have reported them in the paper. That was Tensor's point, that we don't really have enough information in the paper to check the paper's results.

Which, is a major failing.

ETA: you all might want to read the other paper by Gezari that I linked earlier, which purports to show why the speed of light hasn't been measured in the fashion that he thinks it should. I haven't even started it yet myself.

[macaw]

Isn't paragraph 4.2 a discussion about what the author thinks should be avoided? I don't see where 4.2 shows that he is actually doing it.

Paragraph 4.2 , equation (3) is where Gezari is "calculating" light speed.

[dhd40]

The experiment I believe had an accuracy of around 0.99975c and this gives an error margin of 75km/s, which is not very accurate.
Gezari’s experiment is dealing with speed accuracies of a few m/s, which is thousands of times more accurate.
These types experiments that support SR seem very crude by comparison.

I can't remember the accuracy of the experiment (obviously you do?). But at an emitter speed of > 0.9 c (IIRC), even this accuracy seems to be excellent, from my point of view.

[macaw]

I can't remember the accuracy of the experiment (obviously you do?). But at an emitter speed of > 0.9 c (IIRC), even this accuracy seems to be excellent, from my point of view.

wisp is dead wrong, by many orders of magnitude, see post #41.

[dhd40]

wisp is dead wrong, by many orders of magnitude, see post #41.

Ah, thanks, I missed this post

[wisp]

All experiments measuring light speed from moving sources falsify Gezari's paper.




Gezari is NOT measuring light speed, he's measuring the closing speed.
Do you understand the difference?



Light does not travel slower, his formula measures c-v, where v is the receding speed of the reflector.



This is something that is elementary in SR, called "closing speed". Gezari doesn't understand it. Neither do you.





You cannot prove anything in respect to a theory. The scientific method shows that you can only disprove (falsify) a theory. The way prior experiments falsify Gezari's fringe paper.





Gezari is being challenged because he doesn't know basic physics. He measured closing speed and he claims he's measured variable light speed. This is a rookie mistake.




Q5: What happens if there is relative motion between the moon and the Earth? Show the formulas.

Quote Gezari “Observations of moving sources cannot discriminate between special relativity and the old ether hypothesis, and do not favor one over the other, because the invariance of c to motion of the emitting source is a common feature of both special relativity and classical wave theory of light (discussed by Gezari 2009)."

Your response is so heavily biased against any concept of an ether that a proper scientific debate cannot be had.

Your logic seems to be that any discussion or maths concerning:
Absolute frame
Motion through the ether
= wrong, followed by a disrespectful comment about the person for having alternative viewpoint.
Followed up by question(s) that will only be accepted as right if answered in SR terms.