Michelson Morley experiment is no confirmation of Special Relativity

[vanholten]

Hello. Excuse me, but I do question the relevance of the Michelson-Morley experiment regarding Special Relativity.

At the time the MM interferometer didn’t show any phase shift at the receiver within the instrument. The outcome of the MM experiment suggests that the velocity of Earth relative to the Sun being the light source, had no effect on the measurement of the propagation velocity of sunlight in neither directions.

This absence of phase shift is considered to be a confirmation of the second postulate of Special Relativity:

“2. Second postulate (invariance of c)

As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body. Or: the speed of light in free space has the same value c in all inertial frames of reference.”

But is the absence of phase shift indeed a solid confirmation of second postulate postulate? Not quite I think. To measure the propagation velocity of light, you should measure the velocity of one and the same photon. (@swanson)

In the decennia after the MM experiment and SR, Quantum mechanics evolved mead thanks to Einstein explanation of photo-electric effects. The interferometer makes use of mirrors.  However when a photon strikes a mirror and it would be absorbed by an electron, that electron will be excited, gaining energy and momentum. Later, it will drop back to the previous state, emitting a photon. When indeed the electrons in the mirrors of the interferometer act like light sources, they will emit other photons than those being intercepted and absorbed from the sunlight.

If that is true the MM experiment compares the velocity of different photons coming from different light sources.  Of course photons emitted by the MM mirrors would have propagated at the velocity of light but independently from the photons emitted by the Sun.  The fact that no phase shift occurred seems to be exactly in line with quantum mechanical effects and as such is no confirmation of Special Relativity at all.

Perhaps to do a proper test to confirm the irrelevance of motion of the light source, one should make use of the refraction index of light, because that alters when the speed of light deviates.

Edited April 9, 2019 by vanholten

[Strange]

Just now, vanholten said:

At the time the MM interferometer didn’t show any phase shift at the receiver within the instrument. The outcome of the MM experiment suggests that the velocity of Earth relative to the Sun being the light source, had no effect on the measurement of the propagation velocity of sunlight in neither directions.

This experiment has nothing to do with sunlight.

3 minutes ago, vanholten said:

But is the absence of phase shift indeed a solid confirmation of second postulate postulate? Not quite I think. To measure the propagation velocity of light, you should measure the velocity of one and the same photon.

This was a classical experiment, measuring the speed of electromagnetic radiation. Photons were not even known about. Not that I can see why that would make any difference.

4 minutes ago, vanholten said:

However when a photon strikes a mirror and it would be absorbed by an electron, that electron will be excited, gaining energy and momentum. Later, it will drop back to the previous state, emitting a photon. When indeed the electrons in the mirrors of the interferometer act like light sources, they will emit other photons than those being intercepted and absorbed from the sunlight.

I assume any such delay caused by the absorption and reemission of the photon would be (a) very small and (b) constant; ie. independent of the state of motion of the apparatus.

Perhaps you could show some calculations to support your argument?

Note that you are querying one very old (it was done long before SR was published) and not hugely accurate experiment.

You also need to explain why every other observation and experiment is consistent with SR if SR is wrong.

 

!

Moderator Note

Moved to Speculations. Please not the rules of this section of the forum, especially the need for evidence to support your claims.

 

[Sensei]

Quote

Michelson Morley experiment is no confirmation of Special Relativity

..Michelson Morley experiment predates Special Relativity for about 20 years...

 

[studiot]

There seems to be some historic confusion here.

 

The Michelson original interferometer was later shown (by Lorenz) to be incapable of the accuracy required to measure second order effects.

This equipment failed to produce the expected interference.

This was then improved by collaboration with Morley (by increasing the length of the rotating arms) to be more sensitive.

Again there was a null result.

As already noted these experiments were intended to measure the speed of light and detect the effects of the ether.

Lorenz and Fitzgerald then interpreted the result by introducing length contraction as an empirical fact to explain the null result.

But it remained an experimental observation only. There was no theoretical basis provided.

 

Einstein then derived this same value of contraction rom theoretical considerations alone when he introduced Special Relativity.

[beecee]

3 hours ago, vanholten said:

Hello. Excuse me, but I do question the relevance of the Michelson-Morley experiment regarding Special Relativity.

Some important points to remember:

[1] Know the model/theory thoroughly you are attempting to invalidate.

[2] Understand that SR, the model you are pretending to invalidate, has many observational and experimental results and data confirming that model to the best of our ability.

[3] Understand that overwhelmingly supported mainstream theories and models such as SR/GR the BB,  are never going to be invalidated by claims on science forums open to any Tom, Dick or Harry. There is a process to undertake if in the unlikely scenario, you have hit upon something that has been overlooked by professional science and scientists.

[4] Know the scientific methodology.

[vanholten]

3 hours ago, Strange said:

I assume any such delay caused by the absorption and reemission of the photon would be (a) very small and (b) constant; ie. independent of the state of motion of the apparatus.

My point is that the MM experiment is frequently brought forward as confirmation of the second postulate. If your assumption would be correct it would undermine the theory of SR and its underlying calculations all by itself.

[beecee]

56 minutes ago, vanholten said:

My point is that the MM experiment is frequently brought forward as confirmation of the second postulate. If your assumption would be correct it would undermine the theory of SR and its underlying calculations all by itself.

 Ignoring the confirmation of the MM experiment, we are simply unable to perform any other experiment, that shows that the speed of light isn't constant. Couple that with the fact that the other predictions of SR hold up, and have never been invalidated, one can reasonably conclude that the postulate is valid. 

 

Edited April 10, 2019 by beecee

[Strange]

8 hours ago, vanholten said:

My point is that the MM experiment is frequently brought forward as confirmation of the second postulate. If your assumption would be correct it would undermine the theory of SR and its underlying calculations all by itself.

I don't see why. I am pointing out why it is irrelevant. 

You need to show that:

1. This effect exists
2. It is large enough to have a measurable effect on the experiment
3. It is different for each arm of the interferometer (why would it be?)
4. It changes differently in each arm with the rotation of the Earth and/or its orbit round the Sun (why would it?)

Can you do that?

Unless you can do all of those, then it seems that the experiment is successfully confirming that the movement of the apparatus does not change the measured speed of light.

Your statements so far suggest that you don't understand how the Michelson-Morely experiment was performed, nor what it was measuring. 

[swansont]

14 hours ago, vanholten said:

 But is the absence of phase shift indeed a solid confirmation of second postulate postulate? Not quite I think. To measure the propagation velocity of light, you should measure the velocity of one and the same photon. (@swanson)

I'm not sure how you could do that. An interferometer measures a bunch of identical particles, and in this case, all moving at the same speed. I'm not sure why this would not be sufficient. If c were not invariant, all of the photons in each arm would be affected in an identical fashion.

14 hours ago, vanholten said:

In the decennia after the MM experiment and SR, Quantum mechanics evolved mead thanks to Einstein explanation of photo-electric effects. The interferometer makes use of mirrors.  However when a photon strikes a mirror and it would be absorbed by an electron, that electron will be excited, gaining energy and momentum.

Later, it will drop back to the previous state, emitting a photon. When indeed the electrons in the mirrors of the interferometer act like light sources, they will emit other photons than those being intercepted and absorbed from the sunlight.

Reflections do not involve atomic excitations.

 

[vanholten]

23 hours ago, swansont said:

Reflections do not involve atomic excitations.

https://en.wikipedia.org/wiki/Reflection_(physics) 

"mechanism"

-"In the case of dielectrics such as glass, the electric field of the light acts on the electrons in the material, and the moving electrons generate fields and become new radiators. The refracted light in the glass is the combination of the forward radiation of the electrons and the incident light. The reflected light is the combination of the backward radiation of all of the electrons."-

This says the mirrors become radiators that emit light at c independent of their relative motion as usual. The telescope in the MM experiment is the stationary observer of the mirrors so it should measure the light within the instrument to propagate at c.

It is not even a relativistic observation. That is why I don't t see why this experiment confirms the second postulate. It only comments the ether or on the absence of it.

 

[Strange]

11 minutes ago, vanholten said:

"mechanism"

-"In the case of dielectrics such as glass, the electric field of the light acts on the electrons in the material, and the moving electrons generate fields and become new radiators. The refracted light in the glass is the combination of the forward radiation of the electrons and the incident light. The reflected light is the combination of the backward radiation of all of the electrons."-

That is "glass" not a "mirror". Do you see the difference.

But anyway, how does this have any relevance to the fact that the speed of light in both arms is independent of their velocity?

How is it relevant to the many other tests of Lorentz invariance? (Which are all far more accurate than this 132 year old experiment)

 

[swansont]

38 minutes ago, vanholten said:

https://en.wikipedia.org/wiki/Reflection_(physics) 

"mechanism"

-"In the case of dielectrics such as glass, the electric field of the light acts on the electrons in the material, and the moving electrons generate fields and become new radiators. The refracted light in the glass is the combination of the forward radiation of the electrons and the incident light. The reflected light is the combination of the backward radiation of all of the electrons."-

This says the mirrors become radiators that emit light at c independent of their relative motion as usual. The telescope in the MM experiment is the stationary observer of the mirrors so it should measure the light within the instrument to propagate at c.

Nowhere in that explanation does it say that there are atomic excitations. There's a reason for that.

Yes, the classical explanation is that the electrons radiate light. Excitation can only occur for specific wavelengths. It can't be responsible for broadband responses.

38 minutes ago, vanholten said:

It is not even a relativistic observation. That is why I don't t see why this experiment confirms the second postulate. It only comments the ether or on the absence of it.

 

There would be a difference if the speed of light depended on the motion of the source (where any reflection behaves as a source), or motion through an aether.

[Bufofrog]

On 4/9/2019 at 3:26 PM, vanholten said:

The interferometer makes use of mirrors.  However when a photon strikes a mirror and it would be absorbed by an electron, that electron will be excited, gaining energy and momentum. Later, it will drop back to the previous state, emitting a photon. When indeed the electrons in the mirrors of the interferometer act like light sources, they will emit other photons than those being intercepted and absorbed from the sunlight

I think it is very problematic to think of reflection in this way, it makes much more sense to look at a light as a wave and the reflection of that wave.  In the scenario that you presented, if the photon is absorbed by an electron and then re-emitted, there is no reason that the photon would have a trajectory that was 180 degrees different than the incoming photon.  In other words the emitted photon can go in any direction.  Based on your scenario of photon absorption and remittance there would not even be a reflection. 

[Strange]

1 minute ago, Bufofrog said:

I think it is very problematic to think of reflection in this way, it makes much more sense to look at a light as a wave and the reflection of that wave.  In the scenario that you presented, if the photon is absorbed by an electron and then re-emitted, there is no reason that the photon would have a trajectory that was 180 degrees different than the incoming photon.  In other words the emitted photon can go in any direction.  Based on your scenario of photon absorption and remittance there would not even be a reflection. 

I agree. The experiment was testing classical electromagnetic theory (the photon hadn't even been discovered).

Trying to describe the experiment in terms of the speed single photons is meaningless because we can't say anything about the path of an individual photon between the source and when it is detected. 

[swansont]

1 hour ago, Strange said:

That is "glass" not a "mirror". Do you see the difference.

Glass reflects light, with the reflectivity depending on a ratio involving the indicies of refraction, so that has some applicability

The mirror part is usually a conductor, so it's conduction band electrons. No atomic excitations, though

[vanholten]

6 hours ago, Strange said:

agree. The experiment was testing classical electromagnetic theory (the photon hadn't even been discovered).

Sure it wasn’t discovered but it was acting anyhow. So what is your point?

Earth wasn’t flat before it was discovered to be sphere.

6 hours ago, Strange said:

Trying to describe the experiment in terms of the speed single photons is meaningless because we can't say anything about the path of an individual photon between the source and when it is detected. 

The fact that at the current state of science according to you is impossible to describe the speed of individual photons doesn’t imply it’s meaningless. It might even be essential to get a grip on the behaviour of light.

[Strange]

Just now, vanholten said:

Sure it wasn’t discovered but it was acting anyhow. So what is your point?

The point is that relativity is a classical theory so bringing photons into it is irrelevant.

 

[vanholten]

8 hours ago, Bufofrog said:

I think it is very problematic to think of reflection in this way, it makes much more sense to look at a light as a wave and the reflection of that wave.  In the scenario that you presented, if the photon is absorbed by an electron and then re-emitted, there is no reason that the photon would have a trajectory that was 180 degrees different than the incoming photon.  In other words the emitted photon can go in any direction.  Based on your scenario of photon absorption and remittance there would not even be a reflection. 

The idea that there is not even an actual reflection is the whole point. It is supposed to be remittance of energy in the shape of a new photon; a fresh emission creating a fresh wave propagating at c.

If that is going on the mirrors act like stationary light sources with respect to the telescope. From a relativistic perspective there is only a single stationary frame of reference, which as such can't confirm the second postulate.

The thing you might expect caused by the rotation of the interferometer is the Sagnac effect. But that effect is predicted based on classic physics and adapted by relativity, so neither the Sagnac effect can be a confirmation of SR.

I agree it makes you wonder why the remittance of light by electrons is forced in the reflective angle. It needs an explanation. Probably it is imposed by the collaboration of surrounding electrons in the reflective surface?

 

[Bufofrog]

12 hours ago, vanholten said:

The idea that there is not even an actual reflection is the whole point.

Well then that sort of dooms your whole idea, doesn't it? 

When shaving this morning I am fairly certain the person looking at me from the mirror was my reflection.  Hypothesis falsified. 

I guess it is back to the 'drawing board'!  

[Strange]

12 hours ago, vanholten said:

The idea that there is not even an actual reflection is the whole point. It is supposed to be remittance of energy in the shape of a new photon; a fresh emission creating a fresh wave propagating at c.

It is comparing the speed of light in each arm by using interferometry.

Interferometry is a  techniques that uses constructive and destructive interference to measure changes in the phase relationship between two waves.

Light consists of electromagnetic waves. If either speed of the wave or the distance the wave travels changes, then the received phase will change.

You can use see interference with sound waves, water waves and light waves.

This is a purely classical effect. You can use quantum electrodynamics (QED) to do some extremely complicated calculations with large numbers of photons to show that (not surprisingly) they reproduce the same effect (on a statistical basis). 

What you cannot do is measure interference with a single photon.

So, unless you can use QED to show that interferometers do not work (they do) then I'm not sure what your point is.

12 hours ago, vanholten said:

I agree it makes you wonder why the remittance of light by electrons is forced in the reflective angle. It needs an explanation.

I recommend the series of lectures by Feynman on QED. Available as a book and as videos online: http://www.vega.org.uk/video/subseries/8

[studiot]

@vanholten

You haven't responded to my only post in this thread.

 

I remain unsure as to your exact point or question here so can you please set it out more clearly (and preferably more briefly).

 

Surely the point of correspondence between a Theoretical Physics proposition and a measurement is that they both yield the same result, vis the Lorenz Fitzgerald contraction.

By itself that correspondence is insufficient to be called 'the balance of the evidence' butthere have been many other quite different corroborative experiments of the succeeding years.

[swansont]

15 hours ago, vanholten said:

The idea that there is not even an actual reflection is the whole point. It is supposed to be remittance of energy in the shape of a new photon; a fresh emission creating a fresh wave propagating at c.

If that is going on the mirrors act like stationary light sources with respect to the telescope. From a relativistic perspective there is only a single stationary frame of reference, which as such can't confirm the second postulate.

If c weren’t invariant, the speed of light that was transmitted would be different than the light that was reflected, giving rise to a phase difference. Which was not observed.

[vanholten]

9 hours ago, studiot said:

@vanholten

You haven't responded to my only post in this thread.

 

Sorry

On 4/9/2019 at 10:04 PM, studiot said:

There seems to be some historic confusion here.

 

The Michelson original interferometer was later shown (by Lorenz) to be incapable of the accuracy required to measure second order effects.

This equipment failed to produce the expected interference.

This was then improved by collaboration with Morley (by increasing the length of the rotating arms) to be more sensitive.

Again there was a null result.

As already noted these experiments were intended to measure the speed of light and detect the effects of the ether.

Lorenz and Fitzgerald then interpreted the result by introducing length contraction as an empirical fact to explain the null result.

 But it remained an experimental observation only. There was no theoretical basis provided.

 

Einstein then derived this same value of contraction rom theoretical considerations alone when he introduced Special Relativity.

You wrote that  Lorentz and Fitzgerald explained the absence of interference due to length contraction. Then they must have supported the idea of the ether I presume.

So why did Einstein at one hand adapt  the Lorentz/Fitzgerald contraction as the fundament of simultaneity according to  tB - tA = rAB / (c - v )   and   t’A - tB = rAB / (c+v)

and at the other made the ether superfluous with his second postulate? 

Edited April 12, 2019 by vanholten

[Strange]

15 minutes ago, vanholten said:

You wrote that  Lorentz and Fitzgerald explained the absence of interference due to length contraction. Then they must have supported the idea of the ether I presume.

Lorentz certainly did. There is something called "Lorentz Ether Theory" which has exactly the same mathematics as special relativity but just says that it is caused by a magic undetectable "ether". 

As this undetectable ether is (a) unnecessary and (b) undetectable, we can use Occam's razor and say that it can be dropped.

18 minutes ago, vanholten said:

and at the other made the ether superfluous with his second postulate? 

Because it is superfluous.

[studiot]

22 minutes ago, vanholten said:

Sorry

You wrote that  Lorentz and Fitzgerald explained the absence of interference due to length contraction. Then they must have supported the idea of the ether I presume.

So why did Einstein at one hand adapt  the Lorentz/Fitzgerald contraction as the fundament of simultaneity according to  tB - tA = rAB / (c - v )   and   t’A - tB = rAB / (c+v)

and at the other made the ether superfluous with his second postulate? 

 

 

That's correct I did write that because Einstein derived the formula you state as a fundament from his two theoretical postulates.

The first actually being nothing new, just a simple restatement of the already known Principle of Relativity.

The second introduced something new. The invariability of c.

However, like all such axiomatic constructs, the axioms or principles have to be consistent with each other.

The first one allowed Newton's laws to be recast in accordance the Principle of Relativity.

But Einstein wanted to include the laws of Electrodynamics as well (this was, after all, the tile of his paper).

As they stood they were incompatible with the POR

This is why the second postulate was introduced.

He didn't need any more.

 

So I would be interested in the mathematical passage that leads you to believe the equation has the status of a postulate or fundament at you call it.