Hi forum, I followed through Feynamn's derivation to show the different times taken for light by the parallel and perpendicular paths of the Michelson Morley apparatus. He showed that it took longer for light to go to the far mirror and back if it were parallel to the direction the whole apparatus was going at compared to the perpendicular path. He then said that Lorentz suggested if a correction was made to the parallel length of the apparatus it could account for the null result of interference shift. It then said that Einstein thought well this was fine but you still need to introduce a time dilation because the path time for someone moving with the apparatus is different to someone observing it from a stationary reference frame. At what point along this story did Einstein come up with his postulates because it wasn't originally to do with the M and M experiment but something about Maxwells equations ( don't understand this part yet) but also wasn't Lorentz criticised for just adding a length contraction to make the theory fit. At what point did it become accepted? And at what point along all of this does Einstein come up with his famous postulates? Would really appreciate any sort of brief running order of events if possible. Kind regards Glenn.