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Possible 3rd Interpretation of the Michelson-Morley Experiment

  1. Apr 21, 2012 #1
    I am a programmer by trade, so I am more adept at logic than mathematics. One thing that has always perplexed me about the Michelson-Morley experiment was how it is used to reach the conclusion that there is no ether. Just given basic logic, there is a third alternative that I have never seen discussed or explored (in this website or historically). I present it here not as proponent, but to ask if anyone else has heard or read anything about a third alternative interpretation of the Michelson-Morley experiment - a multi-ether universe.

    Below is the analysis that lead me to consider it as a possibility (a small possibility, but a possibility nonetheless). I hope this is the right forum for this.

    The Michelson-Morley experiment tested the following hypothesis:

    Light travels through a medium

    The experimental prediction given the hypothsis was:

    If light travels through a medium, the speed of light should vary as the Earth orbits the sun.

    Of course, as history relates and countless experiments confirmed, there is no difference in the speed of light as Earth travels around the sun. The following conclusions were reached:

    1. Light does not travel through a medium.
    2. There is no medium.

    The logic seems inescapable. However, the jump from conclusion 2 from conclusion 1 is not rigorous. To see why, let's take a simple example.

    We present Neo with a box (sorry for the Matrix reference but I could not resist). We tell Neo that in the box we may or may not have placed some keys. We ask Neo to state his hypothesis about the number of keys in the box and being just human he cannot see into the box. Neo's first hypothesis is:

    There is a single key in the box.

    We tell him that he is wrong and ask him to state his next hypothesis. He says that:

    There must not be any keys in the box.

    We tell him again that he is wrong on two counts. The hypothesis is wrong, and there is a third alternative he has not considered. He scratches his head for a long while, then finally says:

    There must be more than one key in the box.

    We congratulate him on his correct answer and send him off to find other truths about reality.

    Applying this simple thought experiment to the original set of conclusions above, we get instead:

    1. Light does not travel through a single medium.
    2. There is either no medium or more than one medium.

    Prima facie, this third alternative, a multi-medium universe, seems absurd and is probably the reason it was never considered and will never be considered. However, when I consider it seriously (for fun), it leads down some interesting, albeit crazy pathways. For example, it would mean each observer has a medium that is attached to him, conveniently travels with him, is as big as the visible universe, and overlaps all other observer mediums. There are a number of other outlandish possibilities I have thought of, but this is probably not the forum to air them (and be labeled a pyscho).

    Despite the craziness, I am curious if:

    1. the logic leading to the modified conclusions appears sound
    2. anyone else has ever heard of, thought of, or explored this third possibility
    3. the third possibility has ever been experimentally tested
    4. the third possibility could even be experimentally tested

    I hope this does not come off as sophistry and would appreciate any thoughts.
     
  2. jcsd
  3. Apr 21, 2012 #2

    D H

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    That is not the conclusion that was reached. In fact, even your conclusion #1 is not merited. What the experiment showed was that the luminiferous aether posited as the medium through which light travels does not exist.

    Keep in mind that at the time of the Michelson-Morley experiment, every known wave phenomenon was carried by some medium. That no medium is needed comes from quantum mechanics. It shows that electromagnetism is unlike other wave phenomena such as sound waves. Electromagnetism is carried by photons.
     
  4. Apr 21, 2012 #3

    Dale

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    Hi wmikewells, welcome to PF!

    I have not seen any investigation of this in the mainstream scientific literature, so it is probably not suitable for the forum. I doubt that the idea is consistent with existing data.
     
  5. Apr 21, 2012 #4

    Mentz114

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    This is the most important question : if you can't design an experiment which ( in principle) could falsify the third possibility, it is not a scientific theory.
     
  6. Apr 21, 2012 #5
    Thank you for the reply. However, I am somewhat confused by the reply (my own limited knowledge and not your explanation). Is it the current philosophy that EM travels on no medium (whether it be ether or something else), that photons carry their own medium upon which EM travels, that a special medium unlike any other carries EM, or some other explanation? I was not aware that it was quantum mechanics that removed the need for a medium. I always thought it was special relativity that killed it. I guess I have to do more reading.
     
  7. Apr 21, 2012 #6
    SR did not directly kill the idea of a medium. Einstein simply said it was an unnecessary construct . What it did kill was a particular conception of a medium which was material and static and therefore served as a basis for an idea of an absolute rest frame.
    Einstein later in life began to reconsider the idea of a medium of some kind and apparently thought it would not necessarily be incompatible with SR.
    I don't know what the concensus is but I would imagine that many, even in QM, consider this still an open question.
     
  8. Apr 21, 2012 #7
    Glad to be here. I finally got up the nerve to post something.

    That is what I figured. A multi-ether idea is just too "out there". However, I was thinking that it might be consistent with existing data. We have all these mathematical models explaining how things work, but no metaphysical models. For example, multi-medium could explain why light is constant for an observer. Light travels at a consistent speed for an observer because the medium stays with the observer. The mathematical model (special relativity and spacetime) explains how it should work, but a metaphysical model would show why the mathematical model is so.

    I know that quantum physics tells us that there is no Wizard of Oz behind the curtain that is pulling the levers controlling what is "really out there", but I was trying to see if by taking another tack on a century old question, fresh light could be brought to bear. As I mentioned, there are other crazy ideas I have played around with. For example, if each observer has his own medium, the position of each particle could become a simple probability problem. Observer 1's medium has particle A at position X, observer 2's medium has particle A at position X - 0.000001, and so on. Once an observer (any observer )"sees" the particle at a certain location the deviation collapses. After a collapse, if no one "sees" the particle, the deviations will grow again.

    However, I digress. The main point of the post was just to see if anyone else was as crazy as me. Thanks again for the reply.
     
  9. Apr 21, 2012 #8
    That is interesting. I did not know that. I wish I had more time to read. Is there a simple explanation of why quantum mechanics killed ether for good?
     
  10. Apr 21, 2012 #9
    I guess I have my work cut out for me. One more thing to play around with. If in twenty years, you don't hear from me, I guess I wasn't successful. Good thing I have a day job.
     
  11. Apr 21, 2012 #10

    D H

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    First, a couple of ground rules.
    #1: No more speculating.
    #2: Read our rules.

    It is important to think back to the latter part of the 19th century. The rationale for the luminiferous aether was that every wave phenomenon known at that time required some kind of medium. Since Maxwell's equations showed that electromagnetic radiation was a wave phenomenon, it was reasonable to assume that a medium was required for electromagnetism.

    What the Michelson-Morley experiment showed was that the luminiferous aether hypothesized as the medium did not exist. What special relativity showed was that space and time were not of the simple form that underlay the assumptions that went into the luminiferous aether.

    While special relativity did show that Maxwell's equations could be rewritten in a relativistic form, it did not explain what electromagnetism was. Quantum mechanics did. Completely rectifying quantum mechanics and special relativity took some time, about 40 years.
     
  12. Apr 22, 2012 #11
    That is already a mistake as it not absolutely true, it depends on the chosen frame of reference.
    The Earth just as much orbits the Sun as the Sun orbits the Earth.
     
  13. Apr 22, 2012 #12
    How did quantum mechanics explain what EM was, and how was quantum mechanics rectified with special relativity?
     
  14. Apr 22, 2012 #13

    D H

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    Photons.

    Quantum electrodynamics.
     
  15. Apr 22, 2012 #14
    I think a potted history goes more like this:

    Before the MMX, it was assumed that: Light travels through a medium with the properties of the luminiferous aether.

    After the MMX it was concluded that: Light travels does not travel through a medium with the properties of the luminiferous aether.

    There were two main alternative possibilities considered:

    1. Light travels through a medium with the properties of the Lorentz ether. (LET)
    2. Light does not travel through a medium of any kind. (SR)

    Both SR and LET are mathematically identical and produce the same predictions. There is no experiment that can distinguish one theory from the other. It is a matter of interpretation.
     
  16. Apr 22, 2012 #15
    Thanks for the reply. That makes sense given special relativity's "there is no absolute frame of reference". It took me almost a year during college to accept that while taking basic physics courses.

    In case I was misunderstood, I am not a proponent of a single ether or a preferential frame of reference. I was just stating the prediction that Michelson-Morley were testing based on the hypothesis that there is an ether. I was also trying to show that the conclusion that there is no ether based on the negative result of the Michelson-Morley experiment is not entirely rigorous (Prediction: if A, then B / Result: Not B / Ergo: Not A). That historically, we may have limited ourselves by not considering the other possibility (that there are multiple ethers) even if it seems crazy. And I was wondering if anyone had ever considered it (historically or currently). It is just an interesting speculative exercise that has had some fruitful results for me. If I was a betting man, I would say that a multi-ether version of the universe has about as much chance of success as winning the CA state lottery. But at least it has a better chance of success than winning the Mega. Thanks again.
     
  17. Apr 22, 2012 #16
    Thanks. At least I have a starting point.
     
  18. Apr 22, 2012 #17
    I can see why talk of any ether whatsoever has been discarded. Thanks.

    I know that there has been talk of spacetime itself moving (at the start of the Big Bang and possibly at the fringes of the universe). Can one think of spacetime as some sort of medium or even that is not tenable?
     
  19. Apr 22, 2012 #18

    mfb

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    You don't need QM for that. It is sufficient to trust Maxwell's equations, which can give you classical electromagnetic waves. Of course, you need quantum field theory or at least relativistic quantum mechanics if you want to derive Maxwell's equations.


    @wmikewells: I am quite confident that it would be possible to construct SR with an individual medium for every observer. However, this would be just a different way to say "for every observer, light moves with c", together with the other effects of SR. Therefore, this medium would not change anything. What is its purpose then?

    No, that does not work. You wouldn't get interference and other QM effects like that.


    While the sun is quite close to an inertial frame, the earth worse by some orders of magnitude. The earth orbits the sun, while the sun just moves by some kilometers due to the earth.


    Well, "medium"... not in the way that this medium would have any preferred frame or something else. Consider it as spacetime ;).
     
  20. Apr 22, 2012 #19

    Dale

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    Well, you haven't really specified what a multiple ether idea would predict in terms of the quantitative outcome of experiments, so it is impossible to say. But this is definitely not the place for it.
     
  21. Apr 22, 2012 #20
    Yes, I know. I haven't got to the point in my thought play where I can say, for example, that special relativity predicts this and multi-ether predicts something else. I have been spending most of my time seeing if multi-ether could even be used to explain common knowledge stuff (like electric forces, EM waves, etc). I have a line on one idea that is different than special relativity, but this is not the place for it.
     
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