Is There a Flaw in the Michelson-Morley Experiment?

[mtworkowski@o]

Consider that last scenario (a car hitting a parked car at 120 mph) viewed from a frame that's moving at 60 mph relative to the ground. It's going to look exactly the same as a collision between two cars both doing 60 mph in the frame where the ground is stationary (neglecting friction).

I think that might be correct.

 

[mtworkowski@o]

I see a lot of confusion here. At the risk of adding more, allow me to suggest this discussion I have posted on my web site.

http://mysite.verizon.net/mikelizzi/MichaelsonMorelyAnalogy.htm

That's a great link...But does, and I not challenging the logic here, the MM machine have the capacity to turn the end mirrors so that the cross current beam comes back to it's source. Or is that too small an amount to be measured? Remember the one boat had to come back fighting a current and was coming back on a diagonal path.

 

[mtworkowski@o]

Again, you have it wrong. In this airplane analogy, if the plane is traveling east-west, the wind must be traveling north-south. You'll never understand why the MM exp works if you can't comprehend why traveling perpendicular to the ether takes longer the faster the ether is moving.

Btw, when applied to a plane or a boat, this is called crabbing: http://en.wikipedia.org/wiki/Crab_landing

Gee thanks. I can't comprehend what your not saying. I didn't know it was the perpendicular leg that was the one we were looking at. Sorry. I just saw where you said it. Double sorry.

 

[PhilDSP]

Just curious: has anyone performed a related experiment where both group velocity and phase velocity were recorded at the same time?

 

[mtworkowski@o]

Just curious: has anyone performed a related experiment where both group velocity and phase velocity were recorded at the same time?

What does that mean...exactly? I'm a lay person. Sorry.

 

[ZapperZ]

This is a fishing expedition.

"We require that when someone says "I read somewhere" or "I heard somewhere", that the exact valid references is given. Or else, it is impossible to know if what you read is correct or valid, if you interpreted it correctly, or if you are reading some crackpot information. So from now on, please provide the exact source if you wish to understand if what you read or heard is correct."

Who is "We"? You're the only one who has complained about this. It's just a Question.

"However, please note that, per the https://www.physicsforums.com/showthread.php?t=5374", dubious sources are not allowed to be referenced here."

I'm not asking if the material I read is correct. I'm asking about the MME. Why are you reprimanding me for asking a question. Would it have been better to leave out the " I read somewhere"? We all get our ideas from somewhere.

It isn't a reprimand (which would involve an official warning). I ask this from everyone who comes here and mentions the same thing. It is the only way to make sure what you read is the same thing as what you interpret. You don't think having a proper citation is at all important? It also forces you to pay attention to your sources, which is something we hope people will take away from being on here.

While PF is still an open forum, we are trying to impose a stricter standard than other forums that do not demand such quality in their discussion, and one of such standards is the use of clear citations of sources.

Zz.

 

[MikeLizzi]

That's a great link...But does, and I not challenging the logic here, the MM machine have the capacity to turn the end mirrors so that the cross current beam comes back to it's source. Or is that too small an amount to be measured? Remember the one boat had to come back fighting a current and was coming back on a diagonal path.

Insightfull response. Following my analogy would suggest that the MM apparatus was reflecting the beams back into the source (the flame). No, it didn't do that. Both cross current and parallel current beams were ultimately reflected toward an observing screen upon which the constructive or destructive interference would be seen.

I should revise my analogy to suit. That will add more complexity, though.

Oh, and yes, the position and angle of the mirrors were adjustable to the maximum precision of the day. I'd hate to be one turning set screws to move something 10 nanometers.

 

[PhilDSP]

What does that mean...exactly? I'm a lay person. Sorry.

Here is a good explanation: http://en.wikipedia.org/wiki/Group_velocity

 

[mtworkowski@o]

http://en.wikipedia.org/wiki/Group_velocity

 

[mtworkowski@o]

Here is a good explanation: http://en.wikipedia.org/wiki/Group_velocity

Thanks, that's exactly where I was when you posted.

 

[mtworkowski@o]

Since the 1980s, various experiments have verified that it is possible for the group velocity of laser light pulses sent through specially prepared materials to significantly exceed the speed of light in vacuum.

 

[ZapperZ]

Since the 1980s, various experiments have verified that it is possible for the group velocity of laser light pulses sent through specially prepared materials to significantly exceed the speed of light in vacuum.

.. and as in the NEC experiment from many years ago (have been discussed many times in here), you need to closely look at what they did and why no part of the wave actually traveled faster than c (another example where knowing the source and reading the actual source can make a difference). When the pulse is reshaped due to the anomalous dispersive material, you can get the appearance of a group velocity moving faster than c. But nothing here violated SR. Such effect doesn't happen in a typical MM experiment.

http://physicsworld.com/cws/article/print/482

Zz.

 

[mtworkowski@o]

.. and as in the NEC experiment from many years ago (have been discussed many times in here), you need to closely look at what they did and why no part of the wave actually traveled faster than c (another example where knowing the source and reading the actual source can make a difference). When the pulse is reshaped due to the anomalous dispersive material, you can get the appearance of a group velocity moving faster than c. But nothing here violated SR. Such effect doesn't happen in a typical MM experiment.

Zz.

My only reason for pointing it out was that I had read it and that the mathematics had been ambiguous...Excellent link, by the way.

 

[cristo]

My only reason for pointing it out was that I had read it and that the mathematics had been ambiguous.

Doesn't this go back to Zz's point though: where did you read about the experiment? Do you have a source showing the 'ambiguities' in the mathematics?

By the way, I've cleaned up the quote tags in your post on the previous page. It gets pretty confusing telling who said what if you either mess the tags up, or don't put them in. For future reference, to break up a quote so that you can write inside use [ /quote ] and [ quote ] (without the spaces in the brackets). You can hit "quote" on your post above to see the input, and see what I mean.

 

[pmb_phy]

I think I read somewhere that there's a flaw in the Michaelson Morley experiment. Is this true?

Yes. It is true. The flaw has to do with what is known as the extinction theorem. This is mentioned in Special Relativity, by A.P. French, Norton Press, (1968). pages 127-128. The author writes

As mentioned in Chapter 3, this result, although an essential feature of Einstein's formulation of special relativity, did not receive a convincing demonstration until much later. One crucial reason is that the propagation of light through a medium (even a transparent one) involves a continual process of absorption of the incident light and its reemission as secondary radiation by the medium - it takes only a very small thickness of matter to bring about this replacement. Thus, for example, with visible light, a thickness of 10^-8cm of glass or 0.1 mm of air at atmospheric pressure is almost enough to erase any possible memory, as it were, of the motion of the original source. This phenomena, known as extinction (even though it may not involve any appreciable loss of intensity in the light beam), has invalidated some of the observations (e.g. the apparent motions of binary stars, already referred to in Chapter 3) that were at first believed to provide confirmation of Einstein's second postulate - the invariance of c.

I'm sad to see that you had problems asking this question. Its a shame that this kind of thing happens here. Rest assured that not all of us think like that. I admire it when people ask questions like this. Its obvious that if you had more than a mere "heard of" then you probably wouldn't have had to ask this question. Please don't let this discourage ypou from asking questions in the future. If you are given a hard time again then feel free to ask me in PM.

Best wishes and keep asking these probing questions.

Pete

 

[mtworkowski@o]

Thank you Pete.

 

[pmb_phy]

Thank you Pete.

You're welcome.

Do you think that this may be what you were referring to?

Pete

ps - Check your PM.

 

[Nickelodeon]

As I see idea that aether is traveling towards the Earth is most logical taking into account knowledge that light is bent near massive objects.
However I doubt that it is technically feasible to perform interferometer experiment vertically. You will have material deformations due to gravity and probably a lot of vibrations when rotation of apparatus is performed. And predicted outcome of experiment is not obvious to me as well. To make a prediction one needs good understanding of material deformations in accelerated frame.

And it is not obvious that wavelength of the merging beams should be different. Why should they differ?

I think the the light beam going skywards against gravity would be blue shifted and red shifted on its return. The horizontal beam would be unaffected.

 

[mtworkowski@o]

Do you think that this may be what you were referring to?

Something along those lines.

 

[russ_watters]

Yes. It is true. The flaw has to do with what is known as the extinction theorem. This is mentioned in Special Relativity, by A.P. French, Norton Press, (1968). pages 127-128. The author writes...
Pete

Pete, I'd just like to clarify that that passage was actually referring to the MM experiment. It doesn't actually say that in the passage. Is the "this result" it is referring to (from the previous sentence?) a reference to the MM experiment? And if so, how, exactly does it point to a flaw in the experiment?

I am unable to find any confirmation of that (merely googling "michelson morley experiment extinction theorem" turns up only this thread!) and I don't have that book handy...

 

[Doc Al]

Pete, I'd just like to clarify that that passage was actually referring to the MM experiment. It doesn't actually say that in the passage. Is the "this result" it is referring to (from the previous sentence?) a reference to the MM experiment? And if so, how, exactly does it point to a flaw in the experiment?

I am unable to find any confirmation of that (merely googling "michelson morley experiment extinction theorem" turns up only this thread!) and I don't have that book handy...

That passage in French's book does not refer to the MM experiment, but to experiments/observations attempting to prove that the speed of light is independent of the motion of the source. I don't see the relevance of the quoted passage to the MM experiment, nor does French raise the issue of extinction (or any other issue) in his discussion of the MM experiment.

 

[pmb_phy]

Pete, I'd just like to clarify that that passage was actually referring to the MM experiment.

The reason that I quoted it was because it seemed apparent to me that the author was indeed referring to experiments such as the Michelson Morley experiment. I wouldn't have posted it otherwise.

Is the "this result" it is referring to (from the previous sentence?) a reference to the MM experiment?

If you'd like I can scan that portion of the book in and upload it onto my web site. You can then read it yourself and come to your own conclusion.

And if so, how, exactly does it point to a flaw in the experiment?

The way I see it is that the MMX was supposed to determine whether or not the speed of light was independent of the motion of the source. The extinction effect indicates that the speed of light will be relative to the medium, in this case air. Thus if the speed of light actually was independent on the speed of the source then this information would be lost since the speed of light will end up moving relative to the medium itself.

I am unable to find any confirmation of that (merely googling "michelson morley experiment extinction theorem" turns up only this thread!) and I don't have that book handy...

You could always E-mail the author. Let me do some searching myself and see what I come up with. In the meantime I will upload some relavent articles about the extinction effect that appeared in the American Journal of Physics.

I could very well be wrong though. However I did mention this to an expert and he didn't object to this interpretation.

Pete

 

[russ_watters]

The way I see it is that the MMX was supposed to determine whether or not the speed of light was independent of the motion of the source.

Relative to what? In the MMX, the source and detector are stationary wrt each other. From what Doc said, it implies that that passage is talking about a source moving relative to the detector.

If you'd like I can scan that portion of the book in and upload it onto my web site. You can then read it yourself and come to your own conclusion.

No, that answer is good enough for me: what you are saying is that this is your conclusion, not what was actually being said by the author (but an extension of it). It does not appear that your conclusion is part of the conventional interpretation of the experiment.

 

[pmb_phy]

Relative to what? In the MMX, the source and detector are stationary wrt each other. From what Doc said, it implies that that passage is talking about a source moving relative to the detector. No, that answer is good enough for me: what you are saying is that this is your conclusion, not what was actually being said by the author (but an extension of it). It does not appear that your conclusion is part of the conventional interpretation of the experiment.

I could very well be wrong. That's why I'm going to E-mail the author and ask him.

Pete

 

[mtworkowski@o]

Russ and Doc,
Are you guys saying that an experiment related to the ether is not related to the question of a preferential reference frame?

 

[russ_watters]

Russ and Doc,
Are you guys saying that an experiment related to the ether is not related to the question of a preferential reference frame?

That's not anywhere close to what we were saying - we didn't mention anything about the concept of the universal/preferential reference frame in our recent posts. I don't know where you would get that or how to interpret what you are asking. However:

The classical ether is the Universal/Preferential Reference Frame. The MM experiment was the first good evidence that it does not exist.

 

[mtworkowski@o]

That passage in French's book does not refer to the MM experiment, but to experiments/observations attempting to prove that the speed of light is independent of the motion of the source. I don't see the relevance of the quoted passage to the MM experiment, nor does French raise the issue of extinction (or any other issue) in his discussion of the MM experiment.

doc says it here

 

[mtworkowski@o]

Relative to what? In the MMX, the source and detector are stationary wrt each other. From what Doc said, it implies that that passage is talking about a source moving relative to the detector. No, that answer is good enough for me: what you are saying is that this is your conclusion, not what was actually being said by the author (but an extension of it). It does not appear that your conclusion is part of the conventional interpretation of the experiment.

and you say it here

 

[Doc Al]

doc says it here

and you say it here

What are you talking about?

 

[Integral]

It is nice when you have a quoted source at hand.

The quoted phrase: "This result" clearly refers to the last sentence in the previous paragraph:

This then includes the result that light emitted from a source that is moveing relative to the laboratory still has the speed c, no matter how fast the source moves.

In the MM experiment, the source is NOT moveing wrt to the lab therefore this is NOT a disscussion of the MM experiment. Further the last sentence in the quoted paragraph, but not, for some strange reason, included in Pete's quote, goes like this:

We shall now descibe two experiments which do not appear to be vitated by the extinction phenomenon.

edit:
Let me be clear the source of these quotes is Special Relativity by A.P. French copyright @ 1968,1966 by MIT Published by W.W. Norton &Co