Chapter 33, Problem 1FTD

Why was the Michelson-Morley experiment a more sensitive test of motion through the ether than independent measurements of the speed of light in two perpendicular directions?

To determine

The reason why the Michelson-Morley experiment is said to be a more sensitive test of motion through ether than independent measurements of speed of light in two perpendicular directions.

Answer to Problem 1FTD

The interference pattern in Michelson-Morley experiment denotes the existence of ether; it can be treated as a sensitive test of motion through ether than independent measurements of speed of light in two perpendicular directions.

Explanation of Solution

Michelson-Morley experiment was intended to check whether the existence of relative motion between Earth and ether. If it exists, speed of light in different direction should be different. From the experiment, it is proved that there is no relative motion between earth and ether. So, the speed of light is same in all directions. In other words, it proves the absence of ether.

Michelson-Morley experiment obtained this result from the interference pattern formed by two perpendicular light beams. If there is a phase shift between the beams, implies the relative velocity between the earth and ether. In the experiment, the phase shift was negligibly small, means no relative motion exists between the earth and ether. The interference pattern in Michelson-Morley experiment has strong correlation with motion through ether. This is why the Michelson-Morley experiment is said to be a sensitive test of motion through ether than independent measurements of speed of light in two perpendicular directions.

Conclusion: Therefore, the interference pattern in Michelson-Morley experiment denotes the existence of ether; it can be treated as a sensitive test of motion through ether than independent measurements of speed of light in two perpendicular directions.