From: nospam@de-ster.demon.nl   
      
   Paul B. Andersen  wrote:   
      
   > Den 20.02.2026 13:21, skrev J. J. Lodder:   
   > > Paul B. Andersen  wrote:   
   > >   
   > >> Den 19.02.2026 20:00, skrev amirjf nin:   
   > >>> Has anyone tried Michelson-Morley-type experiments with the ECI in mind?   
   > >>   
   > >> If you by "the ECI" mean "the non-rotating frame of reference   
   > >> where the centre of the Earth is stationary", this was very much   
   > >> in Michelson's mind.   
   > >> He tried to measure the speed of the ether in said frame.   
   > >>   
   > >> In Michelson's words:"the motion of the earth through the ether".   
   > >>   
   > >> https://paulba.no/paper/Michelson_1887.pdf   
   > >   
   > > But Michelson was well aware that there should be both a daily effect,   
   > > caused by the Earth' rotation, and a (much larger) yearly effect   
   > > caused by its orbital motion.   
   > >   
   > > IIRC he looked for both, so he 'didn't think ECI',   
   > > (avant la lettre)   
   > >   
   > > Jan   
   > >   
   >   
   > Michelson looked for "the motion of the earth through the ether".   
      
   Right, almost.   
   He expected to find -variations- in the velocity of the Earth   
   with respect to the stationary aether.   
      
   > What he tried to measure was the velocity of the ether relative   
   > to the earth, that is the velocity of the ether in the non rotating   
   > frame of reference where the centre of the earth is stationary -   
   > now called the ECI-frame.   
      
   Wrong. (and of course also an anachronism)   
   All this talk of ECI frames is nothing but a red herring.   
   Forget about it, in connection with M&M.   
      
   Michelson, and everybody else at the time,   
   expected the aether, even called the 'world-aether',   
   to provide an absolute rest frame. (for the whole universe even)   
   It was the only frame in which Maxwell's equations would be valid,   
   with the x and t in them being Newton's absolute space and time.   
      
   > Michelson obviously knew that since the laboratory was on   
   > a spinning Earth, the velocity of the lab would have a diurnal   
   > varying component in the ECI-frame. But he didn't mention   
   > this velocity in his paper, the only velocity he mentions is   
   > "v = velocity of the earth in its orbit".   
   > Michelson probably thought (knew) that the diurnal variations   
   > would be negligible.   
      
   That is a practical matter.   
   Since he was unable to demonstrate the orbital effect   
   there was little point of talking about the smaller rotational effect.   
   AFAIK he did his experiments on a daily basis.   
      
   > The yearly variation of the velocity of the ether due to   
   > the orbiting of the earth around the sun was what he expected   
   > to find.   
      
   Michelson also resorted to 'aether-dragging'   
   as the explanation for his null-result.   
   This only makes sense if the aether in his lab would have   
   a velocity, which it can only have wrt the aether farther out.   
   (on a mountain top for example, where he wanted to repeat M&M)   
      
   > The speed of a point on equator in the ECI-frame is 465 m/s.   
   > The speed of the Sun in the ECI-frame is 2978000 m/s (~1e-4 c)   
   >   
   > The fringe shifts he expected are proporsional to v?/c?.   
   > The expected yearly effect is 40 millions time higher than   
   > the diurnal effect.   
      
   You have an error in you powers of ten here,   
      
   Jan   
      
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