Why ether proves speed of light?

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Discussion Overview

The discussion revolves around the relationship between the concept of ether and the constancy of the speed of light, particularly in the context of Einstein's thought experiments and the implications of Maxwell's electromagnetic theory. Participants explore how discarding ether relates to the conclusions about light's speed and the nature of electromagnetic laws across different reference frames.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question how Einstein's discarding of ether leads to the conclusion that the speed of light is constant, suggesting a need for clarification on this relationship.
  • Others argue that without ether, Maxwell's electromagnetic theory implies that the speed of light must be constant, as it does not depend on the observer's motion.
  • One participant presents an analogy comparing the detection of changes in light speed to detecting ether, suggesting that movement relative to an ether would alter the observed speed of light.
  • Another participant notes that the ether theory predicted that Maxwell's laws would only hold in a specific inertial frame, while Einstein's approach sought to make these laws applicable in all inertial frames.
  • Some participants assert that assuming the constancy of light speed leads to the conclusion that ether is unnecessary, rather than ether being directly obviated by its dismissal.

Areas of Agreement / Disagreement

Participants express differing views on the implications of discarding ether and its relationship to the constancy of the speed of light. There is no consensus on how these concepts interrelate, and multiple competing interpretations are present.

Contextual Notes

Participants highlight various assumptions regarding the nature of ether, the interpretation of Maxwell's equations, and the implications of Einstein's thought experiments. The discussion reflects ongoing uncertainty about these foundational concepts in physics.

Oerg
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When Einstein conducted thought experiments, he imagined himself moving at the speed of light with a mirror in front. He was later forced to discard the idea of ether and he concluded that light must travel at the speed of light regardless of wherever and whatever speed an observer is moving.

My question is: How does discarding the idea of ether make him conclude the constancy of the speed of light?
 
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Oerg said:
When Einstein conducted thought experiments, he imagined himself moving at the speed of light with a mirror in front. He was later forced to discard the idea of ether and he concluded that light must travel at the speed of light regardless of wherever and whatever speed an observer is moving.

My question is: How does discarding the idea of ether make him conclude the constancy of the speed of light?

He believed Maxwell's electromagnetic theory, and without an ether, that theory says c is constant.
 
If you were to detect a change in the speed of light, you would be detecting the ether. Think about this for a few moments. Imagine waves rippling on the surface of a pond, if you start moving then the speed of the waves will change relative to you. The idea is the same.
 
The ether theory predicted that Maxwell's laws would only work exactly in a single inertial reference frame, the rest frame of the ether. In other frames the equations governing electromagnetism would look different, according to the ether theory. Einstein discarded this idea, and tried to see how things would have to work in order for Maxwell's laws to work exactly in every inertial reference frame.
 
Oerg said:
My question is: How does discarding the idea of ether make him conclude the constancy of the speed of light?

It was the other way. Assuming that the speed of light is constant, together with the fact that in Maxwell´s equations any movement relative to an ether does´t have any observable consequences, he concluded that the concept of an ether was no longer needed.
 
Quite right Ich - no longer needed - but not necessarily obviated
 

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