Understanding Wave Direction in Michelson-Morley Interferometer

In summary, the direction of the output beam is not always diagonal for the observer moving relative to the source.
  • #1
ith
12
0
Hello, I would like to understand the Michelson–Morley interferometer, but with the laser being an omnidirectional photon source and a pipe.

http://img822.imageshack.us/img822/6520/interferometer.png [Broken]

There are two pipes, but only one transmits light. The other absorbs the light, because the wave direction is not parallel to the pipe.

One of the images shows the interferometer as seen by the stationary observer.

Now, what about the moving observer? I have a problem understanding the case. Is the wave direction bent for him, relatively to the stationary observer? If yes, how he interprets, that still the same pipe transmits light? If not, what about the direction of the output beam, which should be diagonal for the moving observer in order to hit the mirror?
 
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  • #2
It would be a lot easier to illustrate if you showed the trajectory of a single photon as it traced out two diagonal paths, the outbound one going up and to the right and the inbound one going up and to the left. Then it would be easy to see how this photon will be able to travel through the tube without hitting the walls. Once you see it that way, you can imagine successive photons traversing their own diagonal paths each one above the previous one. Then, if you want, you can draw other illustrations to show how other photons emitted in different directions don't make it through the tube.
 
  • #3
Perhaps I kow already. The direction should be diagonal, because the pipe moves.
 
  • #4
I purposedly wanted to draw the wave, and not photons.

Let the source moves relatively to some observer.
Photons in other images are shown as little balls, that follow their source. So they move diagonally, relatively to the observer. Why waves would do so? Is the bottom image correct for the observer? Would the wave front lag behind the source or move with it just as these "photon balls"?

What if the circles were not wave fronts, but instead bursts of photons. Would not they lag behind? Would they behave differently that wave fronts?
 

1. What is a Michelson-Morley interferometer?

A Michelson-Morley interferometer is an instrument used to measure small changes in the speed of light. It consists of two perpendicular arms, one with a light source and the other with a mirror. The light is split and sent down both arms, then recombined to create an interference pattern. Any changes in the speed of light will cause a shift in the interference pattern, allowing scientists to study the properties of light.

2. How does a Michelson-Morley interferometer work?

A Michelson-Morley interferometer works by splitting a beam of light into two perpendicular paths using a half-silvered mirror. The light travels down both arms and is reflected back towards the center by mirrors. When the two beams are recombined, they create an interference pattern. Any changes in the speed of light will cause a shift in this pattern, which can then be measured and analyzed by scientists.

3. What is the purpose of using a Michelson-Morley interferometer?

The purpose of using a Michelson-Morley interferometer is to study the properties of light, specifically its speed. This instrument was originally used to test the concept of the luminiferous ether, a hypothetical substance thought to be the medium through which light travels. However, the results of the Michelson-Morley experiment ultimately led to the development of Einstein's theory of relativity.

4. What is the significance of wave direction in a Michelson-Morley interferometer?

Wave direction is significant in a Michelson-Morley interferometer because any changes in the speed of light will cause a shift in the interference pattern. This shift can only occur if the light waves are traveling in different directions, as they would if they were traveling through a medium, such as the luminiferous ether. Therefore, the direction of the waves in the interferometer is crucial to the experiment and its results.

5. What did the Michelson-Morley experiment reveal about the nature of light?

The Michelson-Morley experiment revealed that the speed of light is constant, regardless of the direction in which it is traveling. This result was unexpected and contradicted the prevailing theory of the time, which stated that the speed of light would be affected by the movement of the observer through the luminiferous ether. This experiment ultimately led to the development of Einstein's theory of relativity, which revolutionized our understanding of the nature of light and its behavior.

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