Michelson-Morley experiment(s)

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Discussion Overview

The discussion revolves around the Michelson-Morley experiments, particularly focusing on the implications of Earth's acceleration on the results and the interpretation of the experiment's outcomes. Participants explore theoretical considerations, experimental design, and the effects of relative motion in the context of the experiments.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether the Michelson-Morley experiments accounted for Earth's acceleration, suggesting that the laser beam may not propagate in a straight line due to this factor.
  • Another participant notes that, according to General Relativity, while the Earth's center of mass is not accelerating, the surface is, which is relevant to the experiment's setup.
  • A participant argues that the change in the speed of the Earth's surface at the experiment's location is negligible over short data collection periods but could be significant over longer durations, such as 12 hours or six months.
  • One participant expresses confusion about why the time taken for light to travel to the mirror and back should not be the same in all directions, indicating a fundamental misunderstanding of the experiment's mechanics.
  • A later reply draws an analogy to the behavior of two observers in relative motion, questioning if similar reasoning applies to the Michelson-Morley experiment.
  • Another participant reiterates their confusion regarding the time differences in the experiment and suggests an analogy they created for better understanding.

Areas of Agreement / Disagreement

Participants express differing views on the implications of Earth's acceleration and the interpretation of time measurements in the Michelson-Morley experiments. The discussion remains unresolved, with no consensus reached on these points.

Contextual Notes

Some assumptions regarding the effects of Earth's acceleration and the nature of light propagation are not fully explored, and the discussion includes references to external resources for further context.

fluidistic
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"Michelson-Morley" experiment(s)

Do any of the (repeated too) Michelson-Morley experiments took into account that the Earth is accelerating? I.e. that it isn't inertial and that the beam of the laser isn't propagating in a straight line but rather in a curve? How small should this affect the results? I'd rather ask for the 2009 experiments since the "Maximum anisotropy of c is [itex]\leq 10 ^{-17}[/itex]".
Thanks!
 
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Interesting question. Note that as defined in GR, the Earth's center of mass isn't accelerating, but its surface is, and that's what's relevant, because the apparatus is fixed to the surface.
 


The change in the speed of the surface of the Earth where the experiment was located was insignificant over the period of time where they would collect a set of data (one rotation of the apparatus) but it should have been significant over a period of 12 hours or at least a period of six months when they were hoping to measure the speed difference caused by the change in the ether wind.
 


My problem with the M&M experiment is in understanding why effects gained in traveling to the mirror should not be lost in returning to origin. Why should the total time not be the same in all directions?
 


Would you say the same thing about the fact that two observers in relative motion would both continue to measure themselves to be in the center of a single expanding sphere of light that was set off when they were colocated, even though forever thereafter they are traveling further apart?
 


sigurdW said:
My problem with the M&M experiment is in understanding why effects gained in traveling to the mirror should not be lost in returning to origin. Why should the total time not be the same in all directions?

I started out with that same suspicion. It was because I didn't fully understand how the experiment was conducted. May I suggest this analogy I wrote for laymen.

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

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