MMX and the earth's rotational sagnac

  • #1
chinglu1998
182
0
MMX proves light is isotropic in all directions.

Hand held GPS units apply the Earth rotational sagnac correction which means light is not isotropic in all directions at the unit from the satellites.

If a hand held GPS unit is placed at the same location as an MMX experiment, one experiment proves light is isotropic in all directions and the other concludes it is not.

Yet both of these results prove SR.

How is that?
 
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Answers and Replies

  • #2
33,702
11,299
Hand held GPS units apply the Earth rotational correction
Do you have a reference for this?

Since you have trouble understanding basic SR concepts I suspect you may have trouble understanding any such reference and any explanations you get here.
 
  • #3
chinglu1998
182
0
Do you have a reference for this?

Since you have trouble understanding basic SR concepts I suspect you may have trouble understanding any such reference and any explanations you get here.

Thanks for the flaming. I have a few links.


GPS and sagnac
http://relativity.livingreviews.org/Articles/lrr-2003-1/ [Broken]

Because Earth rotates, Sagnac effect is large enough in the GPS and the clocks can’t be synchronized in the rotating frame and there is necessity for different approach to synchronize the clocks. In the GPS synchronization is performed in the Earth-Centered Inertial frame using constancy of speed of light.
http://www.phy.syr.edu/courses/PHY312.03Spring/GPS/GPS.html [Broken]

GPS observation processing must also compensate for another relativistic effect, the Sagnac effect. The GPS time scale is defined in an inertial system but observations are processed in an Earth-centered, Earth-fixed (co-rotating) system, a system in which simultaneity is not uniquely defined.

Read more: http://www.articlesbase.com/gps-articles/about-gps-223087.html#ixzz1AgD2Ds8w
Under Creative Commons License: Attribution
Allan et al., Science, 228 (1985), pg 69.They observed the Sagnac effect using GPS satellite signals observed simultaneously at multiple locations around the world. See GPS.
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#Sagnac

Signals
from a single GPS satellite in common view of receivers at the two locations
provide enough information to determine the time difference between the two
local clocks. The Sagnac effect is very important in making such comparisons,
as it can amount to hundreds of nanoseconds, depending on the geometry. In
1984 GPS satellites 3, 4, 6, and 8 were used in simultaneous common view
between three pairs of Earth timing centers, to accomplish closure in performing
an around-the-world Sagnac experiment. The centers were the National
Bureau of Standards (NBS) in Boulder, CO, Physikalisch-Technische Bundesanstalt
(PTB) in Braunschweig, West Germany, and Tokyo Astronomical Observatory
(TAO). The size of the Sagnac correction varied from 240 to 350 ns.
Enough data were collected to perform 90 independent circumnavigations. The
actual mean value of the residual obtained after adding the three pairs of time
differences was 5 ns, which was less than 2 percent of the magnitude of the
calculated total Sagnac effect [4].
http://www.ipgp.fr/~tarantola/Files/Professional/GPS/Ashby_2003.pdf
 
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  • #4
DrGreg
Science Advisor
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The Sagnac effect applies only to light which travels around a closed loop that encloses a non-zero area, for example a circle, triangle or square. In the MMX experiment, light traveled in a straight line there-and-back enclosing zero area, so the Sagnac effect was irrelevant.
 
  • #5
chinglu1998
182
0
The Sagnac effect applies only to light which travels around a closed loop that encloses a non-zero area, for example a circle, triangle or square. In the MMX experiment, light traveled in a straight line there-and-back enclosing zero area, so the Sagnac effect was irrelevant.

Indeed.
Given a sagnac correction is applied to a GPS unit and clearly the signal did not travel around in a closed loop, then why do mainstream papers apply this correction to GPS?
 
  • #6
chinglu1998
182
0
The Sagnac effect applies only to light which travels around a closed loop that encloses a non-zero area, for example a circle, triangle or square. In the MMX experiment, light traveled in a straight line there-and-back enclosing zero area, so the Sagnac effect was irrelevant.


Geez, I missed this on first read. Light travels in straight lines only in ECI. That is why the sagnac must be applied in ECEF. Light aberration is applied in ECEF , the location of the MMX experiment, based on the Earth's rotation.

Therefore, although one's brain may think the light is moving in the MMX arms in straight lines because the arm are straight, in fact the arms are moving in ECEF and hence, light is moving at an angle in the MMX arms. This is proven everyday by GPS.
 
  • #7
33,702
11,299
In the GPS synchronization is performed in the Earth-Centered Inertial frame using constancy of speed of light.
That seems to explicitly contradict your assertion that GPS handheld units use a Sagnac correction. The citations that you provided that actually detected Sagnac effect using GPS did so via a system of multiple recievers at different locations on the earth, certainly not a Sagnac correction embedded in a hand held unit.
 
  • #8
chinglu1998
182
0
That seems to explicitly contradict your assertion that GPS handheld units use a Sagnac correction. The citations that you provided that actually detected Sagnac effect using GPS did so via a system of multiple recievers at different locations on the earth, certainly not a Sagnac correction embedded in a hand held unit.

In the GPS synchronization is performed in the Earth-Centered Inertial frame using constancy of speed of light.
Yes, I thought that would trip you up. Synchronization is performed in ECEF for the hand held units, not ECI. In ECI, light is measured c in all directions.

The links reveal the sagnac effect to receivers on the ground as you admit. So how would you apply triangulation to determine position without considering the sagnac effect since it has been scientifically proven and you agree? Actually Ashby confesses the sagnac effect is applied to the units.


For atomic clocks in satellites, it is most convenient to consider the motions as they would be observed in the local ECI frame. Then the Sagnac effect becomes irrelevant. (The Sagnac effect on moving ground-based receivers must still be considered.)
http://relativity.livingreviews.org/Articles/lrr-2003-1/ [Broken]

Chapter 5.
 
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  • #10
chinglu1998
182
0
That seems to explicitly contradict your assertion that GPS handheld units use a Sagnac correction. The citations that you provided that actually detected Sagnac effect using GPS did so via a system of multiple recievers at different locations on the earth, certainly not a Sagnac correction embedded in a hand held unit.

This may help you.

Sagac Effect.
--- Maximum Value 133ns
--- Correction applied to receiver.
http://www.intalek.com/Index/Projects/Research/gps.ppt
 
  • #11
chinglu1998
182
0
  • #12
grav-universe
457
1
The MMX allows for a margin of error due to such effects, but the Sagnac effect would be insignificant. The experimenters were trying to find a difference in times for the light pulse to traverse each arm due to the Earth's motion. The Earth travels around the sun at a speed of appromimately 1 / 10000 the speed of light, so the experimenters thought this would make a difference. The difference in times expected between an arm aimed into the Earth's motion and the other aimed perpendicularly to it would be d / (c - v) in the direction of the Earth's motion and d / (c + v) against, while the time either way along the perpendicular arm would be d / sqrt(c^2 - v^2), where d is the length of the arms of let's say 1 meter, giving a difference in times of

(d / (c + v) + d / (c - v)) - 2 d / sqt(c^2 - v^2)

= (d / c) [1 / (1 + v/c) + 1 / (1 - v/c) - 2 / sqrt(1 - (v/c)^2)]

= 3.33 * 10^(-17) seconds

For a maximum difference in times with the Sagnac effect, let's say the light pulses travel completely around the perimeter of the MM apparatus in opposite directions, so the area covered is A = 1 m^2. The apparatus would rotate at the same rate as the Earth. The difference in times for the light pulses will be 4 A w / c^2, where w is the rotational speed of the Earth where w = 2 pi / (24 hours) = 1 / (13751 sec), so we have a difference in times of just 3.232 * 10^(-21) seconds. The difference with the Sagnac effect is still 4 orders of magnitude smaller than the expected value, and that is with the maximum effect of having the pulses travel all the way around, which would be nowhere near that otherwise. So while the Sagnac and other effects might not allow the result of the MMX to be precisely null, it is nowhere near what the experimenters were looking for and expecting with the motion of the Earth. Of course as well as this, the Sagnac effect deals with rotation, not inertial motion. Only inertial frames measure an isotropic speed of light, but even non-inertial frames are well within the margin of error for subtle issues such as the Sagnac effect as compared to what would otherwise be expected.
 
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  • #13
chinglu1998
182
0
The MMX allows for a margin of error due to such effects, but the Sagnac effect would be insignificant. The experimenters were trying to find a difference in times for the light pulse to traverse each arm due to the Earth's motion. The Earth travels around the sun at a speed of appromimately 1 / 10000 the speed of light, so the experimenters thought this would make a difference. The difference in times expected between an arm aimed into the Earth's motion and the other aimed perpendicularly to it would be d / (c - v) in the direction of the Earth's motion and d / (c + v) against, while the time either way along the perpendicular arm would be d / sqrt(c^2 - v^2), where d is the length of the arms of let's say 1 meter, giving a difference in times of

(d / (c + v) + d / (c - v)) - 2 d / sqt(c^2 - v^2)

= (d / c) [1 / (1 + v/c) + 1 / (1 - v/c) - 2 / sqrt(1 - (v/c)^2)]

= 3.33 * 10^(-17) seconds

For a maximum difference in times with the Sagnac effect, let's say the light pulses travel completely around the perimeter of the MM apparatus in opposite directions, so the area covered is A = 1 m^2. The apparatus would rotate at the same rate as the Earth. The difference in times for the light pulses will be 4 A w / c^2, where w is the rotational speed of the Earth where w = 2 pi / (24 hours) = 1 / (13751 sec), so we have a difference in times of just 3.232 * 10^(-21) seconds. The difference with the Sagnac effect is still 4 orders of magnitude smaller than the expected value, and that is with the maximum effect of having the pulses travel all the way around, which would be nowhere near that otherwise. So while the Sagnac and other effects might not allow the result of the MMX to be precisely null, it is nowhere near what the experimenters were looking for and expecting with the absolute motion of the Earth. Of course as well as this, the Sagnac effect deals with rotation, not inertial motion. Only inertial frames measure an isotropic speed of light, but even non-inertial frames are well within the margin of error for subtle issues such as the Sagnac effect as compared to what would otherwise be expected.

Nice post.


The Michelson-Morley Experiment (the MMX)
The Michelson-Morley experiment (MMX) was intended to measure the velocity of the Earth relative to the “lumeniferous æther” which was at the time presumed to carry electromagnetic phenomena. The failure of it and the other early experiments to actually observe the Earth's motion through the æther became significant in promoting the acceptance of Einstein's theory of Special Relativity, as it was appreciated from early on that Einstein's approach (via symmetry) was more elegant and parsimonious of assumptions than were other approaches (e.g. those of Maxwell, Hertz, Stokes, Fresnel, Lorentz, Ritz, and Abraham).
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html

The fact is, the null result supported relativity.

Those that understand basic math understand the result cannot be null.

So, a null MMX has been used to prove SR. But, it is not actually null.
 
  • #14
JesseM
Science Advisor
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The fact is, the null result supported relativity.

Those that understand basic math understand the result cannot be null.

So, a null MMX has been used to prove SR. But, it is not actually null.
Seems like another case of reviving an old argument you raised on another forum:

http://www.sciforums.com/showthread.php?t=105408&page=25

If someone just doesn't understand some mainstream conclusions they can of course ask questions, but the rules here don't allow for aggressively disputing mainstream results in SR as you did on the other forum and appear to be doing above, make sure to read the IMPORTANT! Read before posting thread.
 
  • #15
chinglu1998
182
0
Seems like another case of reviving an old argument you raised on another forum:

http://www.sciforums.com/showthread.php?t=105408&page=25

If someone just doesn't understand some mainstream conclusions they can of course ask questions, but the rules here don't allow for aggressively disputing mainstream results in SR as you did on the other forum and appear to be doing above, make sure to read the IMPORTANT! Read before posting thread.

Uh, what mainstream am I disputing? The sagnac correction is a mainsteam fact. I agree with the modern experiments of GPS with distances to measure correctly.

Please be specific on what mainstream I am disputing.

If you are disputing the mainstream fact of the sagnac correction in GPS, I have supplied many many many mainstream papers for that experimentally verified position.

Please indicate your position so I can understand.
 
  • #16
chinglu1998
182
0
Seems like another case of reviving an old argument you raised on another forum:

http://www.sciforums.com/showthread.php?t=105408&page=25

If someone just doesn't understand some mainstream conclusions they can of course ask questions, but the rules here don't allow for aggressively disputing mainstream results in SR as you did on the other forum and appear to be doing above, make sure to read the IMPORTANT! Read before posting thread.

I read my stuff over there. I can't see where I am refuting any GPS facts. Can you please prove your flat Earth accusations? I support the conclusions of modern non-flat Earth GPS experimental data and did in all my posts here and there that I have proven with the most accepted mainstream links.

Perhaps you can be more specific.
 
  • #17
grav-universe
457
1
Nice post.
Thanks.


The fact is, the null result supported relativity.

Those that understand basic math understand the result cannot be null.

So, a null MMX has been used to prove SR. But, it is not actually null.
The expected effect resulting solely from the inertial motion was not found. Other insignificant effects due to rotation or anything else do not apply as they are not what MMX was intended to measure, so do not affect the overall outcome of the experiment for inertial motion only.
 
  • #18
chinglu1998
182
0
Thanks.


The expected effect resulting solely from the inertial motion was not found. Other insignificant effects due to rotation or anything else do not apply as they are not what MMX was intended to measure.

Again nice post.

6 months ago, you could find many links that claimed MMX supported isotropic light.

Try to look now. There are none. Therefore, MMX does not prove lorentz invariance and if any readers believe this, look for it.

If anyone finds a mainstream paper of flat Earth times, I have a modern one based on verified GPS data waiting to counter.

So, here is the bottom line, what does MMX prove? Nothing.

So, what is the experimental basis of special relativity without MMX?
 
  • #19
grav-universe
457
1
Again nice post.
Thanks again. :smile:

6 months ago, you could find many links that claimed MMX supported isotropic light.

Try to look now. There are none. Therefore, MMX does not prove lorentz invariance and if any readers believe this, look for it.
A lesser number of links showing that MMX supports Lorentz invariance means it's not true? That doesn't sound right. :smile:

So, here is the bottom line, what does MMX prove? Nothing.

So, what is the experimental basis of special relativity without MMX?
It proves that light can be measured isotropically in any arbitrary inertial frame, since it travels away and back with the same two way time over the same distance in any direction. From there, SR follows.
 
  • #20
PAllen
Science Advisor
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Again nice post.

6 months ago, you could find many links that claimed MMX supported isotropic light.

Try to look now. There are none. Therefore, MMX does not prove lorentz invariance and if any readers believe this, look for it.

If anyone finds a mainstream paper of flat Earth times, I have a modern one based on verified GPS data waiting to counter.

So, here is the bottom line, what does MMX prove? Nothing.

So, what is the experimental basis of special relativity without MMX?

See: https://www.physicsforums.com/showthread.php?t=229034

Harping on this like harping on the relatively well accepted fact the first measurement of light bending in an eclipse was swamped by experimental errors; ignoring hundreds of additional tests of GR of enormously greater precision; same goes for SR.

Please desist.
 
  • #21
JesseM
Science Advisor
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Uh, what mainstream am I disputing?
That the MMX (and other more recent experiments of the same type) is evidence for SR because SR predicts a null result. Aren't you disputing this claim?

(note, I'm not saying the rotation of the Earth has precisely zero effect on what we should predict for the MMX to an infinite number of decimal places, just that any rotational effect is too miniscule to change the fact that SR predicts a null result to within the limits of experimental error).
 
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  • #22
chinglu1998
182
0
See: https://www.physicsforums.com/showthread.php?t=229034

Harping on this like harping on the relatively well accepted fact the first measurement of light bending in an eclipse was swamped by experimental errors; ignoring hundreds of additional tests of GR of enormously greater precision; same goes for SR.

Please desist.

I want to desist. But that would mean I need to toss all of the GPS evidence proven everyday in the trash.

GPS proves light is not isotropic in the ECEF frame everyday. Do you refute the mainstream evidence?
 
  • #23
chinglu1998
182
0
A lesser number of links showing that MMX supports Lorentz invariance means it's not true? That doesn't sound right. :smile:
No, there was a paper that has been accepted modernly and refutes MMX using GPS data. It is even at Microsoft's publishing outlet.

It proves that light can be measured isotropically in any arbitrary inertial frame, since it travels away and back with the same two way time over the same distance in any direction. From there, SR follows.

You cannot claim ECEF sagnac is true and MMX proves isotropy.
 
  • #24
chinglu1998
182
0
That the MMX (and other more recent experiments of the same type) is evidence for SR because SR predicts a null result.

(note, I'm not saying the rotation of the Earth has precisely zero effect on what we should predict for the MMX to an infinite number of decimal places, just that any rotational effect is too miniscule to change the fact that SR predicts a null result to within the limits of experimental error).

Why don't you show me links that MMX proves light is isotropic in post GPS papers. I want to see them.
 
  • #25
JesseM
Science Advisor
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Why don't you show me links that MMX proves light is isotropic in post GPS papers. I want to see them.
Try searching "Michelson-Morley" on google books, you'll find plenty of books more recent than the GPS system (which dates to 1973).
 
  • #26
PAllen
Science Advisor
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I want to desist. But that would mean I need to toss all of the GPS evidence proven everyday in the trash.

GPS proves light is not isotropic in the ECEF frame everyday. Do you refute the mainstream evidence?

The key is the following:

"So, what is the experimental basis of special relativity without MMX?"

Your way of dealing with this is intellectually fraudulent. A tendentious misinterpretation of MMX is taken to refute it plus hundreds of other experiments supporting SR.
 
  • #27
chinglu1998
182
0
Try searching "Michelson-Morley" on google books, you'll find plenty of books more recent than the GPS system (which dates to 1973).

No,GPS did not consider Sagnac until the 80's. You live in flat Earth times.

Anyway bring a modern article from a mainstream university. I want to see it.
 
  • #28
chinglu1998
182
0
The key is the following:

"So, what is the experimental basis of special relativity without MMX?"

Your way of dealing with this is intellectually fraudulent. A tendentious misinterpretation of MMX is taken to refute it plus hundreds of other experiments supporting SR.

So, are you claiming all the mainsteam papers are false on GPS which is proven everyday in which MMX is false?

Can you prove MMX is true and GPS is true? I will knock that one down quick.


That is where we are for your argument to be true. Are you going to defend your position under this logic?
 
  • #29
russ_watters
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chinglu1998, this is your thread and these are your claims being discussed. You need to start substnatiating them with mainstream, peer reviewed papers. Laying down a claim and demanding to be proven wrong is not acceptable.

Putting words in other peoples' mouths is also not acceptable. Like with your other thread, the mainstream view, obviously, is that Relativity is correct and no mainstream experiments - as interpreted by mainstream scientists in mainstream journals - contradict this. The other posters are following that, so implications that they are contradicting the mainstream view is putting words in their mouths they didn't say.

This forum is not a game, it is here to teach people science. If you're not here to learn, then stop wasting our time.
 
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  • #30
PAllen
Science Advisor
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So, are you claiming all the mainsteam papers are false on GPS which is proven everyday in which MMX is false?

Can you prove MMX is true and GPS is true? I will knock that one down quick.


That is where we are for your argument to be true. Are you going to defend your position under this logic?


MMX was intentded to measure anisotropy from a particular source, based on a particular model, and the expected effect was a particular size. Whether done now or a 100 years ago, an effect of the then expected size does not occur. Therefore MMX came out against expectations, leading to the Lorentz interpretation and also verified Einstein's SR interpretation. That a different, much smaller effect, might be detected (though even this is disputed - whether any design of MMX could detect Sagnac) is irrelevant.

Further, there are hundreds of other experiments in the link I provided validating SR.

To sum up your response to this with the following, which is your concluding quote from your post #18:

"So, what is the experimental basis of special relativity without MMX?"

is, pure and simple intellectual dishonesty.
 
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  • #31
JesseM
Science Advisor
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No,GPS did not consider Sagnac until the 80's.
Are you just saying that until the 80s all the calculations involving GPS devices were done in the nonrotating ECI frame rather than the ECEF frame? If not, where are you getting this claim? Certainly the GPS designers would have known about the Sagnac effect, which dates back a lot further than 1973.
chinglu1998 said:
Anyway bring a modern article from a mainstream university. I want to see it.
Find it yourself--try google scholar. It's pretty obvious this isn't a matter of you accepting relativity but believing modern physicists don't accept MMX, you are trying to say physicists are wrong to accept MMX as evidence for relativity, and are using this argument to question SR itself (as evidenced by your rhetorical question "So, what is the experimental basis of special relativity without MMX?") I'm not going to play the game of looking for a source that exactly matches your specifications, but just so you can't say you weren't shown a source, here is a book that discusses modern variations on MMX on page 152 which you can read on google books, it's published by Springer which is a respected publisher of scientific texts (and the book's original publication date is 1999, this is a 2nd publishing from 2006). And here is the abstract of a published journal article which backs up my claim that rotational effects into account are not precisely zero, but in the MMX they would be too small to make any observable difference to the experimental results:

Reinterpretation of the Michelson-Morley experiment based on the GPS Sagnac correction
By examining the effects of rotational and orbital motions of the Earth on wave propagation in the global positioning system and an intercontinental microwave link, it is pointed out that the Earth's orbital motion has no influence on these earthbound wave propagations, while the Earth's rotation does contribute to the Sagnac effect. As the propagation mechanism in the Michelson-Morley experiment cannot be different from that in the aforementioned ones, it is concluded that due to the Earth's rotation, the shift in interference fringe in this famous experiment is not exactly zero. However, by virtue of the round-trip propagation path, this shift becomes second order and hence is too small to observe within the present precision.
Anyway, feel free to try to continue to argue that relativity should predict a non-null result for the MMX, but you can't claim ignorance now, so doing that will probably just get you banned.
 
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  • #32
berkeman
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Not sure about the ban yet, but this thread is closed for now.
 

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