stars for his interferometer light source, getting the null result. 1925 – the Michelson–Gale–Pearson experiment produces a positive result while attempting to detect the effect of Earth's rotation on the velocity of light. The significance of the experiment remains debated to this day, but this planetary Sagnac effect is measured by ring laser gyros and taken into account by the GPS system. 1925 April – Meeting of the National Academy of Sciences. Arthur Compton explains the problems with the Stokes aether drag solution. Miller presents his positive results of the aether drag. 1925 December – American Association for the Advancement of Science meeting. Miller proposes two theories to account for the positive result. One consists of a modified aether theory, the other a slight departure from the Contraction Hypothesis. 1926 – Roy J. Kennedy produces a null result on Mount Wilson Auguste Piccard and Ernest Stahel produce a null result on Mont Rigi. 1927 – Mount Wilson conference. Miller talks of partial entrainment Michelson talks about aether drag and altitude differential effects K. K. Illingworth produces a null result using a clever version of the MMX with a step in one mirror that dramatically improves resolution. The resolution is so good that most partial entrainment systems can be eliminated. 1929 – Michelson and F. G. Pease perform the Pearson experiment and produce a null result. 1930 – Georg Joos produces a null result using an extremely accurate interferometer placed entirely in vacuum. 1932 – the Kennedy–Thorndike experiment uses an interferometer with arms of different lengths and not at right angles. They measure over several seasons and record on photographs to allow better post-measurement study. The Kennedy Thorndike experiment becomes one of the fundamental tests for SR, proving the independence of light speed wrt to the speed of the emitting source. The other two fundamental tests are Michelson–Morley experiment (proves light speed isotropy) and Ives–Stilwell experiment (proves time dilation) 1934 – Georg Joos publishes on the Michelson–Gale–Pearson experiment, stating that it is improbable that aether would be entrained by translational motion and not by rotational motion. 1935 – Hammar experiment disproves aether entrainment 1951 – Paul Dirac writes that currently-accepted quantum field theory requires an aether, although he never formulated this theory completely. Debate slows 1955 – R. S. Shankland, S. W. McCuskey, F. C. Leone, and G. Kuerti performed an analysis of Miller's results and explained them as stemming from