"valid" system at all, i.e., nobody can of course be prohibited to illustrate the actually arising effect by a "relative aether wind", but this is only an image from the standpoint of relativity, like "the sun is rising".
For the decision "aether or non-aether?", all rotating systems are failing according to the relativity-theoretical view. The existence of the aether is proven, as soon as the following is proven: an inertial system is preferred over another inertial system; thus as soon as one – in the comparison of inertial frames among each other – finds an "effect" of the discussed or of similar kind. On the other hand, every inertial system is preferred over rotating systems from the relativity standpoint, and vice versa; when inertial- are compared with rotational systems, or rotational system are mutually compared, one therefore must always find some "effects".
Braunschweig, Technische Hochschule, January 1914.
