Special Relativity Question: On the Ether

1. Dec 19, 2009

Fawkes511

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 travelling at any angle to the "ether wind" anyway? Or would light naturally behave like a swimmer?

Last edited: Dec 19, 2009
2. Dec 19, 2009

denverdoc

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. Dec 21, 2009

chubbc

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