Special Relativity Question: On the Ether

In summary, the introduction to the ether in Lillian Lieber's The Einstein Theory of Relativity explains that the ether is assumed to not move with the Earth. This assumption is based on the belief that a medium is necessary for the propagation of light, and the ether was considered to be that medium. However, it was not assumed that the ether was completely still, only that the likelihood of it having the same velocity as the Earth was very low. The Michelson-Morley experiments were conducted multiple times to account for the Earth's movement, and it was concluded that the Earth could not be stationary in the ether for more than one point in its orbit per year. This is because an object not experiencing a force will travel in a straight
  • #1
Fawkes511
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I am a high school student working through Lillian Lieber's The Einstein Theory of Relativity. In the introduction to the ether, it is assumed that the ether would not move with the Earth. Although Lieber does cite one book (Understanding Relativity, Sartori), presumably including the several known "facts" that she mentions, I do not have access to a large public library and thus to this book. Could someone explain why the ether does not move with the Earth (in the nineteenth century ether model)? If that were not the case, wouldn't there be a "deflection" in the path of light traveling at any angle to the "ether wind" anyway? Or would light naturally behave like a swimmer?
 
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  • #2
Well you do have the internet. It's been a long time since I have studied relativity, but as I recall the assumtion that some media was necessary to support the propgation of light--just as a material is necessary for the propogation of sound or any other kind of wave. Ether was the medium. Note that it wasn't assumed that the ether was still, just that the likelihood of having the same velocity as the erth was zilch. See this link:
http://en.wikipedia.org/wiki/Michelson–Morley_experiment
 
  • #3
This assumption was only partially made. The Michelson-Morely experiments were redone several times during the year in case they performed the experiment in a time when the Earth was stationary in the aether. The Earth could not be stationary in the aether for more than one point in its orbit per year (if that, as Denverdoc said its very unlikely) for the simple reason that a medium not experiencing a force travels in a straight line (inertia) whereas the Earth travels in a circular/elliptical orbit
 

Related to Special Relativity Question: On the Ether

1. What is the concept of "ether" in special relativity?

The concept of "ether" in special relativity refers to a hypothetical substance that was once believed to exist as a medium for light waves to propagate through. This concept was later rejected by Einstein's theory of special relativity, which states that the speed of light is constant in all frames of reference and does not require a medium to travel through.

2. How did Einstein's theory of special relativity disprove the existence of ether?

Einstein's theory of special relativity introduced the concept of space-time, which states that the laws of physics are the same in all inertial frames of reference. This means that the speed of light is always constant, regardless of the observer's frame of reference. Therefore, there is no need for a medium like ether for light to propagate through.

3. Was the concept of ether widely accepted before Einstein's theory?

Yes, the concept of ether was widely accepted in the scientific community before Einstein's theory of special relativity. This was because it provided a way to explain the behavior of light and electromagnetic waves. However, with the introduction of special relativity, the concept of ether was no longer needed.

4. Are there any experiments that have been done to test the existence of ether?

Yes, there have been several experiments conducted in the late 19th and early 20th century to detect the existence of ether. The most famous of these is the Michelson-Morley experiment, which aimed to measure the Earth's motion through the ether. However, all these experiments failed to detect any evidence of ether and supported Einstein's theory of special relativity.

5. Are there any modern theories that still incorporate the concept of ether?

No, the concept of ether is no longer used in modern theories of physics. While some theories, such as string theory, may use the term "ether" to refer to a different concept, it is not the same as the classical concept of ether used in the 19th century. Einstein's theory of special relativity remains the most widely accepted and supported theory of space and time.

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