Michealson Morley Experiments

[MrGamma]

Michelson Morley ran an experiment using an interferometer to look for the aether relative to the earth's sun.

 

He found a displacement which was proportional to the square of the velocity...

 

If the aether was relative to the sun. Effectively this experiment found a displacement pattern which is visible within the light spectrum but relative to the sun. Correct? What did he find which was thrown away as experimental error?

 

Any help would be much appreciated as I'm still trying to wrap my head around this one.

 

http://en.wikipedia.org/wiki/Michelson-Morley_experiment

[Sayonara]

While you wait for replies I suggest searching the forums, as we have had many a discussion on the MM experiment. Some of those threads may help.

[MrGamma]

While you wait for replies I suggest searching the forums, as we have had many a discussion on the MM experiment. Some of those threads may help.

 

Thank you... Sometimes I overlook the obvious... I found this in one of the threads...

 

"By the context of his speech, it appears that Einstein says the following two things:

 

1) Special Relativity does not disprove the existence of an Ether. That was always known: Ether is just simply NO LONGER NECESSARY in the formulation of Electromagnetism, according to SR.

 

2) In General Relativity, spacetime interacts with matter. And it is this concept of spacetime that Einstein names "Ether" in his 1920 text."

 

So I guess my questions are... What did Michealson-Morely find? Is it nothing more than a "frame of reference"? Or is it something like the electro-magnetic interference from the sun? It must be something... right?

[ydoaPs]

I thought it was what they DIDN'T find that was important.

[MrGamma]

I thought it was what they DIDN'T find that was important.

 

Well if they found "Nothing"... then why are there two separate theories... One which work with "nothing"... and one which works without "nothing"...

 

Clearly... if there was "nothing" then there would be no need to make two different "algorithms"... correct?

 

Whatever he found was "proportional to the square of the velocity" and they were trying to detect movement relative to the sun... so... what did they find?

[mooeypoo]

Saying there's no need for Aether in the theory is like saying there is no need for the invisible pink unicorns in the theory.

 

If it's undetectable, unseen, unidentified and un-affecting-anything, then it's unnecessary and unimportant.

 

Michaelson Morley set out to find the Aether by setting up certain effects (or expected observations) that should be seen if Aether exists.

 

The 'methodology' was something of the spirit of "If Aether exists, then X, Y, Z must happen/be seen".

 

Since these observations were not found, it meant one of two things:

(1) Aether does not exist.

(2) Aether exists but we cannot observe it, interact with it or measure it or its effects on anything else.

 

Statement #2 is not science.

Hence, the conclusion out of the experiment (and others after) was that Aether does not exist.

 

 

 

~moo

[MrGamma]

If it's undetectable, unseen, unidentified and un-affecting-anything, then it's unnecessary and unimportant.

 

I completely understand that it's not needed... I'm just wondering what the measurement was that he found. It was proportional to the square of the velocity. And the measurement according to Einstein effects how Special Relativity and General Relativity works.

 

Was the measurement really nothing? If so... Why two different relativity theories. Is it common place to throw away a measurement whose proportion is square to the speed of the velocity?

 

Does one theory work with a frame of reference while the other doesn't? The experiment was trying to find the aether in relation to the sun. Doesn't this in itself imply that the sun would be the center of our universe?

[Klaynos]

The result was massively below what was expected by theory, and was inside the error of the equipment (impossible to tell between a measurement and a 0, it's VERY difficult to measure a 0).

 

Experiments since then have also measured within their error of 0.

 

So you've no choice but to interoperate the measurement as evidence of no aether.

 

There's actually 3 theories of relativity.

 

The Theory of Relativity, which is classical and applies on earth, throw a ball on a moving train and measure it from a train and from the platform and you'll get this.

The Special Theory of Relativity, which is an adjustment to classical mechanics when velcocites are close to the speed of light, this simplifies to the first theory for v << c.

The General Theory of Relativity, for acceleration and gravity situations, this simplifies to Special Relativity and therefor classical mechanics in normal situations.

[MrGamma]

Experiments since then have also measured within their error of 0.

 

There is a history of the measurements taken over history on this page.

 

http://en.wikipedia.org/wiki/Michelson-Morley_experiment

 

Not one of those experiments hit their expected fringe shift. IN fact... All of them were under their estimates. Example...

 

Joos in 1930

Fringe shift expected 0.75

Fringe shift measured 0.002

 

Nobody has hit their mark in all of history.

 

What exactly is a fringe shift in relation to the sun? What is it? And why do experiments continually fall under their estimates?

[insane_alien]

well, the fringeshift is an effect that the aether should produce. the fact that they always fall below expected values is because without an aether fringe shift should be 0. 0 is in the error range for all experimental results.

[MrGamma]

well, the fringeshift is an effect that the aether should produce. the fact that they always fall below expected values is because without an aether fringe shift should be 0. 0 is in the error range for all experimental results.

 

I understand... The fringe shift should reveal the aether as a medium which moves in relation to the sun. I'm convinced that there is no aether. I am also convinced that the detection of nothing should produce a result of 0. These experiments however produce results.

 

Example...

 

Michelson et al. in 1929

 

Fringe shift expected 0.9

Fringe shift measured 0.01

 

 

If they expected to find nothing with a fringe shift of 0.9 but instead found a fringe shift of 0.01.

 

I would think that the search for nothing should return exactly that. 0 right on the money each and every time. But... this experiment suggests that Zero is in fact 0.9 and they found 0.01. So essentially this experiment produced a result of -0.89. Correct?

 

Perhaps I am mis-understanding what a fringe shift is. Right now I am under the impression it's the speed of light as it travels in right angles towards each other. If the speed of light being is a constant. Why do they continually find discrepancies in it?

[John Cuthber]

What they found (just as an example- I don't have the real numbers) is that while they expected a shift of 0.9 they found a shift that was "too small to see". Then the calculated how small a shift they would be able to see and found that calculation gave 0.01 So they know that any shift is less than 0.01 and that they cannot rule out the idea that it might be zero. Someone could always say "the shift was 0.001" but there's no way to check that without a better experiment.

 

It doesn't matter- if I have a theory that says that there are less than ten bananas in my kitchen and someone finds there are lots, but stops counting after they find the first 20, they have still disproved the theory even though they don't have an exact measurement of the number of bananas.

 

"I would think that the search for nothing should return exactly that. 0 right on the money each and every time."

why?

If I weigh a rock and send it to a friend and he weighs it the difference in weight (ignoring a few oddities) should be exactly zero- but would you expect it to be. That would require that my balance was perfectly accurate and so was his.

Then we come back to those oddities. If he is at a different latitude then his measurement will differ from mine because of the earth's spin. If he's at a different height above sea level that will also have an effect.

I can try measuring those factors and try to compensate for them, but I can't do that perfectly so I expect to get some value for the difference in weights that is near zero, but not exactly zero.

[D H]

I would think that the search for nothing should return exactly that. 0 right on the money each and every time.

No, and doubly so in a well-designed experiment. First, there is always experimental error. Forget about this particular experiment for a bit. Suppose you have an instrument that measures some quantity. You measure a value of 0.01. Does that mean your measured value is not zero? Not necessarily. All instruments yield somewhat erroneous values. Instruments exhibit bias and random error. A bias means the instrument consistently yields a high (or low) readings. A random error means the instrument might read 0.01 one time and -0.01 the next time for the exact same input. A well-designed instrument will have a bias as close to zero as possible and a very low random error. It is impossible to completely eliminate either bias or random error. A reading of 0.01 is consistent with a true value of zero if the expected bias + random error might well exceed the reading.

 

But... this experiment suggests that Zero is in fact 0.9 and they found 0.01. So essentially this experiment produced a result of -0.89. Correct?

No. This "fringe shift expected" is what the experimenters expected to see if the luminiferous aether existed and altered the apparent speed of light. The result of 0.01 is almost certainly inconsistent with the expected value of 0.9 and might well be consistent with a value of 0. The particular experiment you cited does not have an entry in the "Experimental Resolution" column. The only experiment that does specify a resolution is the 1927 Illingworth experiment. The measured fringe value was 0.0002 and the resolution was 0.0006. Thus the 0.0002 is completely consistent with a true value of 0.0 and is completely inconsistent with a true value of 0.07.

Why do they continually find discrepancies in it?

They don't.

[insane_alien]

basically what john is saying is that errors are inherent to all measurements.

 

take when you measure something with a ruler. if you take it to the nearest measurement point you could say it is 1cm +/- 0.5mm which means that the true calue coule be anything from 0.95cm to 1.05cm

 

if i measure something that has an error of +/- 1 and i get an reading of 0.5 then the actual value could be anything from -0.5 to 1.5 including 0.

 

until i find a more accurate way to make the measurement i can never know.

[Klaynos]

If you measure something with a ruler, you can measure it to the nearest 0.5mm,

 

If you expect something to be 10mm if it's correct or 5mm if it's not correct, and you measure it to be 5.5mm +/- 0.5mm then you are pretty sure that it's incorrect.

[MrGamma]

No. This "fringe shift expected" is what the experimenters expected to see if the luminiferous aether existed and altered the apparent speed of light. The result of 0.01 is almost certainly inconsistent with the expected value of 0.9

 

Well... Why would they expect anything is my real question? The aether is by definition "nothing".

 

What would make somebody think that the aether ( which is nothing ) should fringe shift light? Is this a property of light itself? To fringe shift when it's pointed at itself at right angles?

 

Why would they use the sun as a point of reference and not the center of the Milky way?

 

take when you measure something with a ruler. if you take it to the nearest measurement point you could say it is 1cm +/- 0.5mm

 

If I took a measurement with a ruler twice... and each time it was measured I came up with a different result. Then I would immediately realize my measurement was wrong. And I would measure it a third time.

 

Why does light fringe shift at right angles? Shouldn't this produce an accurate reading in all circumstances seeing that the speed of light is a constant?

 

If I weigh a rock and send it to a friend and he weighs it the difference in weight (ignoring a few oddities) should be exactly zero- but would you expect it to be. That would require that my balance was perfectly accurate and so was his.

 

So essentially... these measurements of the Aether are ignoring a few oddities... what oddities are they ignoring? Would the fringe shift be different if they used the center of the earth as reference for the shift as opposed to the sun? Honestly... If I used a scale to weight a rock and then used another scale to measure a rock and I came up with an different weight... I would have to calibrate my scale to the other to get the exact same result. So essentially... over history they have "calibrated" the fringe shift of light to what people expected to be zero?

 

Is that what this experiment does? It calibrates the properties of light to zero in relation to the sun using the theory that nothing should exist?

Edited August 18, 2008 by MrGamma
multiple post merged

[insane_alien]

Well... Why would they expect anything is my real question? The aether is by definition "nothing".

 

thats the definition now, thats not the definition then however.

[swansont]

Well... Why would they expect anything is my real question? The aether is by definition "nothing".

 

What would make somebody think that the aether ( which is nothing ) should fringe shift light? Is this a property of light itself? To fringe shift when it's pointed at itself at right angles?

 

Why would they use the sun as a point of reference and not the center of the Milky way?

 

The aether was the medium and preferred reference frame through which light purportedly traveled. Since stellar aberration had already been observed by Bradley in 1727, scientists knew we could not be stationary with respect to the ether. This is why M-M did not expect zero as a result. AFAIK the aberration indicated that the sun should be the reference point under aether theory, since it was an equal amount no matter what the position of the earth was, with only a direction change. (though there were other complications, but then, the model was wrong)

[D H]

Well... Why would they expect anything is my real question? The aether is by definition "nothing".

What ever gave you the idea that the luminiferous aether is "nothing"? The luminiferous aether (the proper name of the thing the Michelson-Morley experiment was trying to find) was definitely not "nothing". It was some unknown physical material that occupied all space. Physicists of that day did not know what the luminiferous aether was, but they fervently believed it was something rather than nothing. Light was widely believed to be a pure wave phenomenon, and all wave phenomena they were familiar with required some underlying medium through which they propagated.

If I took a measurement with a ruler twice... and each time it was measured I came up with a different result. Then I would immediately realize my measurement was wrong. And I would measure it a third time.

Regarding your measurements with a ruler. Suppose you use something a bit more precise than a ruler -- say a caliper accurate to 0.01 inches -- and measure the length of some object to be 6.01, 5.99, 6.00, 6.02, and 6.00 inches in five separate measurements. Are you going to try again, or are you going to say that your measurements all agree with one another?

 

A major aspect of any scientific experiment that involving measurements is getting a handle on the errors in that experiment. Two measurements of the same quantity are rarely identical, and hence the need for examining error. Having measurements that are too good is one of the hallmarks of bad science -- possibly something as simple as observer bias all the way up to out-and-out forgery.

[MrGamma]

What ever gave you the idea that the luminiferous aether is "nothing"?

 

Perhaps what I am thinking is that Nothing is the medium through which energy travels through. I do not believe that scientists of the time could have had the correct means to determine if an Aether existed or not. So I have been trying to understand the experiment better so that I can understand how it has influenced history and our understanding of the universe. That's all.

 

I have a great deal of respect for science. My limited understanding of particle physics has me questioning the validity of the following video. I have made the connection between their findings regarding the origins of mass and the Aether. Is this a correct view?

 

[D H]

Since you responded to my question, I must reiterate: Stop with the stupid videos, please. Give a recap, or even better, a paper.

[MrGamma]

Since you responded to my question, I must reiterate: Stop with the stupid videos, please. Give a recap, or even better, a paper.

 

My apologizes... I am not fluent with Particle Physics or Quantum Theory enough to know how to dissect the papers... This is the list of publications of the person who gave the lecture...

 

http://web.mit.edu/physics/facultyandstaff/faculty_documents/wilczek_pubs_15_march_04.pdf

 

I was just wondering if the lecture was related to the Aether in any way shape or form.

[Klaynos]

The luminiferous aether was definitely believed to be something, and they devised an experiment that if it got the predicted value would show that it existed, otherwise that it didn't. Everyone expected a positive result. It failed. It was then found that aether wasn't a requirement of wave propagation, so the theory then matched the negative experiment.

 

There will always be errors on experiments, and it's notoriously hard to measure 0, generally because of the shapes of probability curves... for example when finding polarisation states of polarisers you don't look for extinction because it's nearly impossible to find, you look for the peak in intensity because it's sharper, and less hidden in the noise and error of the experiment.

 

Science has moved on alot since the MM experiment, but their result is still very valid.

[MrGamma]

Science has moved on alot since the MM experiment, but their result is still very valid.

 

I understand this... I did not understand that precise measurements could vary.

 

In a Hubble video there was mention that during a solar eclipse the effects of gravitational lensing were noticed to change. Stars in the sky changed their position and the effects of gravitational lensing were "proven".

 

To quote a website...

 

"He studied the properties of a solar eclipse on various expeditions around the world. This research eventually confirmed Albert Einstein's theory that as light passes a very massive star, its path is bent due to gravity."

 

I was unaware that the moon's gravity could bend light and I would think this bending of light could have been observed without the need of a solar eclipse. ( you could just look at the moon as it passed a star right? )

 

The nature of the Michealson Morely experiment attempted to determine the presence of a Luminous Aether and it's movement relative to the Sun. If the experiment was carried out during a solar eclipse would it have effected the outcome at all?

 

This article from Nasa ( suggests to me anyways ) that the possibility exists, "Decrypting the Eclipse"

 

The very nature of a Foucault pendulum detecting the spin of the earth and the Aether experiments using interferometers which eventually led to the discovery of the laser gyroscope has me thinking that the perhaps the MM experiment would have found something different during the tests if performed during an eclipse? Would he have found something if he wasn't using the Sun as a point of reference for the tracking of the Aether? Essentially... the Aether should move relative to itself... shouldn't it?

 

I understand my speculation is completely psuedo but please understand it is just me trying to understand the nature of light, gravity, aether and spin, direction and how they work with each other.

 

How does one use the light from the sun and the sun as a point of reference to determine the movement of the Aether when logically... he was trying to detect a property of light itself as it came from the sun? Shouldn't the speed of light be a constant? And any variation found in the experiment, which is stated as being...

 

“since the displacement is proportional to the square of the velocity”

 

...be a discovery of the property of light itself?

 

If you were running modern physics experiements on the speed of light and you discovered a displacement which was proportional to the square of the velocity... would you write it off as an error?

Edited August 27, 2008 by MrGamma

[Klaynos]

I watched teh first 2 mins of the video, and it appears to be talking about vacuum fluctuations which is nothing to do with the aether.

 

IIRC the MM experiment used a coherent light source, not the sun, the fact the earth is moving (and the sun is moving) is the reason that taken at different times of the year the speed of light should be measured to be different as the aether would be moving at a different speed relative to the earth.