notesonly.in

Step 1: Build the interferometer with a half‑mirror (beam splitter) and two mirrors, one 10 meters long and the other 10 meters long, perpendicular to each other. Step 2: Shine a laser beam onto the beam splitter. The light splits into two beams that travel to each mirror and back. Step 3: The two returning beams recombine at the splitter and create an interference pattern on a screen. Step 4: Rotate the entire device 180 degrees so that the long arm now points in the opposite direction. Step 5: Count how many bright fringes shift. If the Earth moves through the ether, you should see about 20 fringe shifts. Step 6: Observe that almost no fringes shift – the result is “null.” Step 7: Conclude that the speed of light is the same in all directions, which supports Einstein’s theory.