Newton, Poincare, Lorentz and Einstein (around 1921) believed that there is a preferred frame of reference. Einstein changed his mind when he saw that he is going against mainstream. Michaelson Morley experiment and subsequent experiments are regarded by most people as proof that there is no preferred frame or reference, but this is a question of philosophical approach to relativity theory, because you can regard contraction and time dilation relative to preferred frame of reference and equotations are still the same. General relativity is still non Machian theory, which is regarded as shortcoming by some, but most physicist dont understand what does it mean and generally dont care. So, after short intro, here comes the question: Is there any obvious and clear evidence which is proving that there is no preferred frame of reference?