A concise answer would suffice. Thank you. short Videos about special relativity and answer the following questions suggested by the films. t. th the Michelson-Morley experiment, the motion of the earth through the ether was supposed to be detected via a change in the interference pattern produced by the interferometer when the apparatus was rotated. However, no change was observed. Why did they expect to see a change, and why was no change seen? Solution The basic aim of the michelson-morley experiment was to verify the existance of ether, a medium assumed to be present in our enviroment which is responsible for the propogation of light. For this two light one perpendicular to the medium and one parallel to medium were made to travel and then interfere. since both would travel different amount in the ether they would have phase difference and that would cause shift in the interference pattern. But no as such result was observed. The main reason was there is no such thing as ether, light is a electromagnetic wave which requires no medium for its propogation. And also without ether there would be no special frame of reference against which different observer can measure the motion so it was deduced ( by Einstein) that speed of light remain constant in all inertial frame. .