SO writes:
Myself writes:
When? I provided substantial evidence in which relativistic calculations are required in modern day applications such as GPS which you totally ignored and metaphorically stuck your fingers in your ears. You even stated you did not read the links I provided.
Actually, what you provided were links that claimed that they were using the Sagnac effect as the main reference.
Actually the Sagnac effect is fully consistent with relativity not contradictory. For example onf of the links I provided state this:
Relativity in the Global Positioning System" by Dr. Neil Ashby writes:
The purpose of this article is to explain how relativistic effects are accounted for in the GPS.
Although clock velocities are small and gravitational fields are weak near the earth, they give rise to significant relativistic effects. These effects include first- and second-order Doppler frequency shifts of clocks due to their relative motion, gravitational frequency shifts, and the Sagnac effect due to earth’s rotation. If such effects are not accounted for properly, unacceptably large errors in GPS navigation and time transfer will result. In the GPS one can find many examples of the application of fundamental relativity principles
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.)
Gravitational frequency shifts and second-order Doppler shifts must be taken into account together. In this section I shall discuss in detail these two relativistic effects, using the expression for the elapsed coordinate
For a low earth orbiter such as the Space Shuttle, the velocity is so great that slowing due to time dilation is the dominant effect, while for a GPS satellite clock, the gravitational blueshift is greater
There is an interesting story about this frequency offset. At the time of launch of the NTS-2 satellite (23 June 1977), which contained the first Cesium atomic clock to be placed in orbit,
it was recognized that orbiting clocks would require a relativistic correction, but there was uncertainty as to its magnitude as well as its sign. Indeed, there were some who doubted that relativistic effects were truths that would need to be incorporated. A frequency synthesizer was built into the satellite clock system so that after launch, if in fact the rate of the clock in its final orbit was that predicted by general relativity, then the synthesizer could be turned on, bringing the clock to the coordinate rate necessary for operation. After the Cesium clock was turned on in NTS-2, it was operated for about 20 days to measure its clock rate before turning on the synthesizer. The frequency measured during that interval was +442.5 parts in compared to clocks on the ground, while general relativity predicted +446.5 parts in . The difference was well within the accuracy capabilities of the orbiting clock. This then gave about a 1% verification of the combined second-order Doppler and gravitational frequency shift effects for a clock at 4.2 earth radii.
As understanding of the numerous sources of error in the GPS slowly improved, it eventually made sense to incorporate the correct relativistic calculation.
GALILEO is a project of the European Space Agency, intended to put about 30 satellites carrying atomic clocks in orbit. In contrast to GPS which is free to users, the GALILEO system ultimately will be funded by user fees. Information released in 2006 by the GALILEO project states that relativistic corrections will be the responsibility of the users (that is, the receivers). This means that GNSS devices capable of receiving both GPS and GALILEO signals will have to contain additional relativity software to process GALILEO signals. Since no factory frequency offset is applied to atomic clocks in the GALILEO satellites, relativity effects will cause satellite clock time to ramp away from TAI and will require large correction terms to be transmitted to users.
BEIDOU is a satellite navigation system being developed and deployed by the People’s Republic of China. In its early stages, there were three satellites capable of transponding timing signals between a master control station and receivers on the ground. Timed pulses are sent from the control station, to the satellites, and then to ground-based receivers, which sends them back through the satellites to the control station. With the timing information, and topographic information (the receivers have to be on earth’s surface), the receiver position can be computed and relayed back to the receiver. Since receivers must also transmit, they are bulky.
The principal relativistic correction involved here is the Sagnac effect, which can amount to several hundred nanoseconds.
The GPS is a remarkable laboratory for applications of the concepts of special and general relativity. GPS is also valuable as an outstanding source of pedagogical examples. It is deserving of more scrutiny from relativity experts.
Alternative global navigation systems such as GLONASS, GALILEO, and BEIDOU are all based on concepts of clock synchronization based on a locally inertial reference system freely falling along with the earth. This concept, fundamentally dependent on a relativistic view of space and time, appears to have been amply confirmed by the success of GPS.
Plans are being made to put laser-cooled clock(s) having stabilities of and accuracies of , on the International Space Station. This will open up additional possibilities for testing relativity as well as for making improvements in GPS and in other potential navigational satellite systems.
Also
Around-the-World Relativistic Sagnac Experiment Allan, D.W., Weiss, M., and Ashby, N. Science, 228, 69—70, (1985) writes:
In 1971 Hafele and Keating carried portable atomic clocks east and then west around the world and verified
the Sagnac effect, a special relativity effect attributable to the earth's rotation. In the study reported here observations of the effect were made by using electromagnetic signals instead of portable clocks to make clock comparisons. Global Positioning System satellites transmit signals that can be viewed simultaneously from remote stations on the earth; thus an around-the-world Sagnac experiment can be performed with electromagnetic signals. The effect is larger than that occurring when portable clocks are used. The average error over a 3-month experiment was only 5 nanoseconds.
SO writes:
Myself writes:
We can go on this proverbial merry-go-round say "my source is better than your source", however if you want to try to disprove the theories of relativity and the 90+ years of work based on them, you will have to provide something more conclusive than a wikipedia article, which ironically states that SR explains the MM experiment while saying that the M/G experiment is compatible with both the stationary aether and SR ideas (meaning this experiment does not conclusively prove one or the other, however there are many, many other experiments as well as applications that do prove SR).
Actually I also gave a link to the PR article. But the thing is, the test does not square with the SR. No if you take into account the Michelson Morley experiment too!
See above. Quote the exact references in your replies so we know what you are talking about. It is useless throwing links back and forth to each other without knowing exactly where you are pulling this information from. I will do the same.
BTW, the MM experiment which was created to test for the presence of a luminescent ether actually disproved the presence of this ether.
This is what Michelson himself says in his
‘The Relative Motion of the Earth and the Luminiferous Ether’ article describing his experiment in American Journal of Science, 1881, 22: 120-129:
Michelson writes:
The interpretation of these results is that there is no displacement of the interference bands.
The result of the hypothesis of a stationary ether is thus shown to be incorrect, and the necessary conclusion follows that the hypothesis is erroneous.
This conclusion directly contradicts the explanation of the phenomenon of aberration which has been hitherto generally accepted, and which presupposes that the earth moves through the ether, the latter remaining at rest.
SO writes:
Experiment gave the measured speed of 8 km/s. The predicted speed was 30 km/s.
My understanding is that they incorrectly calculated the rotational velocity of the Earth using in which they failed to utilize the superposition property of waves. Taking this into consideration the calculations accurately depict a rotational speed for the Earth of 30 km/s. However, they may have inadvertently also detected the absolute motion of the Earth through space itself Source:
The Michelson and Morley 1887 Experiment and the Discovery
of Absolute Motion
SO writes:
So they actually interpreted this as a null result and said that there was no aether. So in other words, relativity came along and said that light speed is independent from the observer and that's why we got the null result.
A null result means that they did not detect the presence of an ether based on the results of the experiment. There was 0.005 fringe shift compared to the expected 0.04 fringe shift if ether slowed down the light. Which in taking into account a 130 year old experiment using antiquated equipment is pretty close to 0?
SO writes:
But than came the MG experiment which gave the right predicted results, which means that there is an aetehr, and that it is the aether that is rotating.
Those results being what? Please connect the dots. Again saying so doesn’t make it so.
So the only reason why we got the null result in the MM experiment is because the Earth is not moving.
I am not even sure if this is worth debating? Are you fucking serious?
Um, ok. So how do you explain the retrograde motions of the planets in the sky? How about the phases of Venus? How do you explain a Foucault pendulum? The parallax shift of stars every 6 months? The Coriolis effect of hurricanes and other weather phenomena? etc. etc.
How the hell do we send geosynchronous satellites to orbit the Earth and not fall out of the sky if the Earth is not rotating?
BTW, we get the null result (meaning virtually no fringe shifting) because there is no difference in time the light proceeds in both perpendicular directions and returns to the interferometer detector. This means there is nothing slowing down the light in either direction aka no ether.
SO writes:
So you can't say relativity explains the MM experiment since the recorede speed was supposed to be 0.
No, the differences between the speed of light going in two perpendicular directions are supposed to be near 0 (to prove there is no ether) not the recorded speed of light!?! This experiment was nearly 130 years ago and the results were pretty close to 0. New experiments result in an anisotropy of to 210-13. That is 0 when you take into consideration the inaccuracy of the equipment involved as I stated previously.
SO writes:
Myself writes:
Saying it so, doesn't make it so.
BTW, it detected the angular velocity of the Earth with no outside reference (in other words it measured the angular velocity of the Earth w/ reference to spacetime itself) as shown here:
The scientists said so, not me.
Show me.
SO writes:
And what they meant by an outside reference was something outside the mechanism. The aether is passing through all matter, so it is obviously inside the mechanism. Why do you think they used light? Becasue the aether is supposed to be a medium that carries light waves. And in reference to that they were measuring the rotation.
Are we talking about MM still? If so that was not measuring the rotation of anything. It was measuring the speed of light traveling in two perpendicular directions. As far as the MG experiment, accurately measuring the angular speed of the Earth in reference to spacetime was a beneficial by-product of this experiment and it very closely matched the sidereal estimate of the Earth’s rotation.
SO writes:
Myself writes:
So are you saying the Earth does not rotate??
Isn't it obious?
Answered above. Show me answers to the above questions about phenomena that can only be explained by a rotating Earth and heliocentric solar system.
SO writes:
Myself writes:
SO writes:
But the point remains there is aether.
Baseless assumption.
It's not an assumption it's a common knowledge.
Common by who? The flat earth society and geocentric nutcases?
SO writes:
The firnge shifts in MG experiment would be 0 if there were no aether.
Now we are shifting back to the MG experiment? No, because in the MG experiment we have to take into consideration the Sagnac effect which we didn’t have to do with the MM experiment due to its different construction (MM’s round-trip propogation path vice MG’s two rectangular interferometers). As a result the MG will result in a non-0 fringe shift when taking into consideration the Sagnac effect. See ‘Reinterpretation of the Michelson-Morley experiment based on the GPS Sagnac correction’ Ching-Chuan Su 2001 Europhys. Lett. 56 170-174 (I was able to access it using my university’s online research database).
SO writes:
Myself writes:
Or they detected the effects of SR which is why this experiment is inconclusive in proving one or the other.
How exactly does SR produce fringe shifts? It doesn't.
SR doesn’t ‘produce’ anything. SR is a theory which explains the nature of spacetime.
Fringe shifts are the measurement of out of phase light patterns as a result of an interferometry experiment such as the Michelson-Morley experiment. Fringe shifts result from a delay of one light beam going one direction from another going perpendicular the same distance. An ether would result in a fringe shift of 4% the size of a single fringe. This did not occur i.e. the fringe shift was less than 20% of what would be expected if an ether existed (recent more accurate experiments result in a nearly close to 0 fringe shift ). Therefore this experiment does not contradict the SR model of spacetime.
Edited by DevilsAdvocate, : No reason given.
Edited by DevilsAdvocate, : No reason given.
For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.Dr. Carl Sagan
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