Did the Fitzgerald-Lorentz Contraction Explain the Michelson-Morley Experiment?

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Discussion Overview

The discussion centers on the Michelson-Morley Experiment (MME) and whether the Fitzgerald-Lorentz contraction provides an adequate explanation for its null result. Participants explore the objectives of the MME, the implications of the ether theory, and the relevance of Lorentz contraction in the context of the experiment.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants assert that the MME aimed to test the speed of light in relation to the hypothetical ether wind, expecting a difference based on the direction of motion.
  • Others argue that the Lorentz contraction does not satisfactorily explain the null result of the MME, suggesting that the absence of an ether medium is a more plausible explanation.
  • A participant questions the rationale behind expecting the relative velocity of the Earth and ether to be less than a quarter of Earth's orbital velocity, pointing out inconsistencies in the ether theory.
  • Some contributions highlight confusion regarding the application of Lorentz transformations versus the Fitzgerald-Lorentz contraction, with one participant emphasizing that the contraction does not account for the necessary conditions to yield a null result.
  • Another participant suggests that if the experiment yields unexpected results, it is essential to re-evaluate the underlying theory and assumptions rather than solely focusing on the experimental procedure.
  • There is a mention of the implications of accepting either relativity or Galilean transformations, with differing expectations for the experiment's outcomes based on these frameworks.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the Fitzgerald-Lorentz contraction to the MME, with no consensus reached on whether it adequately explains the experiment's null result. The discussion remains unresolved regarding the implications of ether theory and the interpretations of the experimental outcomes.

Contextual Notes

Participants note the complexity of applying Lorentz contraction to the MME, highlighting the need for clarity on definitions and assumptions related to ether and the nature of light propagation. There are unresolved questions about the conditions under which the MME was conducted and the theoretical frameworks applied.

HannonRJ
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What was the objective of the MME?
Did the Lorentz contraction actually explain the null result of the MME?
 
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HannonRJ said:
What was the objective of the MME?
Did the Lorentz contraction actually explain the null result of the MME?

The Michelson-Morely experiment was set up to test the (at the time) rather unexpected prediction of Maxwell's equations that the speed of light in vacuum is constant and independent of the frame of reference.

Alternatively, it could be looked at as an attempt to measure the speed of the 'luminus ether wind'.
 
HannonRJ said:
What was the objective of the MME?

The original objective was to show that the speed of light was different moving in the direction of the hypothetical ether wind than it would be moving across at a right angle to the ether wind. If ether really existed, it would be unreasonable to believe that it travels along with the Earth at all times of the year. You would expect the planet to be moving through it at some time of the year, if not all the time.

Did the Lorentz contraction actually explain the null result of the MME?

Since the observers were moving along with the apparatus, I don't think so.

What explains the null result of the MME is that there really is no ether that is the medium of which light travels. If one could set up an MME but with sound waves, it would show a positive result if the air was moving passed and through the apparatus. That's because air is the medium in which sound propagates. There is no such medium for electromagnetic waves.

r b-j
 
According to M+M, the purpose of their experiment was to test the validity of Fresnel's hypothesis that "the ether is supposed to be at rest except in the interior of transparent media." M+M concluded that their experiment indicated that, "...the relative velocity of the Earth and the ether is probably less than one sixth of the eatth's orbital velocity, and certainly less than one-fourth".[The American Journal of Science, No. 203, Nov. 1887, p333.]

If one applies the Lorentz contraction to M+M's math (in the cited article), it does not explain the results of the experiment.

Why did the MME produce the result that it did?
 
HannonRJ said:
According to M+M, the purpose of their experiment was to test the validity of Fresnel's hypothesis that "the ether is supposed to be at rest except in the interior of transparent media." M+M concluded that their experiment indicated that, "...the relative velocity of the Earth and the ether is probably less than one sixth of the Earth's orbital velocity, and certainly less than one-fourth".[The American Journal of Science, No. 203, Nov. 1887, p333.]

the only curiosity to me is why they would expect the "the relative velocity of the Earth and the ether [to be] certainly less than one-fourth" Earth's orbital velocity at all times of the year. if the Earth happened to be moving along with the ether wind in spring, it should be moving rapidly through it in the fall. the only reason to suspect not would be some wild theory that the ether wind moves along side of the Earth wherever it is, as if the Earth is the center of all things.

If one applies the Lorentz contraction to M+M's math (in the cited article), it does not explain the results of the experiment.

i have absolutely no idea why anyone would be applying any Lorentz transformation to the experiment at all. is the observer moving relative to the apparatus?

Why did the MME produce the result that it did?

isn't the ostensible answer obvious? you need to read what responses given you previously.

when an experiment turns out different than the expectation, the first thing to do is double and triple check the procedure to make sure you did it right. and then rerun it to see if the previous result was spurious. i think that "M+M" did that multiple times. if you've conceived the experiment properly and carried out carefully and without error, and it turns out opposite of theory, it's time to recheck the theory and the underlying assumptions of it.

r b-j
 
HannonRJ, if you already [think you] know the answer to your questions, what is the purpose of this thread?
 
"i have absolutely no idea why anyone would be applying any Lorentz transformation to the experiment (Michelson-Morley) at all. is the observer moving relative to the apparatus?"

Your comment implies that you accept the tenets of relativity. If that is the case, then you would expect a null result from the experiment, knowing that the velocity with which your frame is moving has no effect on observations within your frame. However, if you believe that Galilean transformations apply, then you would expect a non-null result as Michelson did.
 
rbj said:
i have absolutely no idea why anyone would be applying any Lorentz transformation to the experiment at all. is the observer moving relative to the apparatus?
The question relates to the Lorentz contraction (actually first thought up by Fitzgerald, so it is also known as the Fitzgerald-Lorentz contraction), not the Lorentz transformation. The Fitzgerald- Lorentz contraction did explain the MME result. The problem was that no one could explain why distances would contract in the direction of the motion through the ether by exactly the right amount needed to make the speed of light appear to be equal in all directions.

AM
 

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