purpose of Michelson-Morley Experiment?

[abrowaqas]

What is the purpose of Michelson-Morley Experiment?
Why it is called the failed experiment? what is the contradiction between Michelson-Morley and Einstein?
What is Ether in that experiment?
is it a liquid?

[jtbell]

http://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment

[ghwellsjr]

What is the purpose of Michelson-Morley Experiment?
Why it is called the failed experiment? what is the contradiction between Michelson-Morley and Einstein?
What is Ether in that experiment?
is it a liquid?
Most scientists at the time thought that light was a modulation of some kind of medium based on Maxwell's equations which they called the luminiferous ether. It was not a liquid in the sense that a liquid consists of molecules of matter that can move around. They thought that it was rigid prior to the experiment. They thought that it was universally stationary and that the earth moved through it and so there should be an ether wind which would change during the day and during the different seasons.

MMX was designed to detect this ether wind but it failed to detect any ether wind, no matter what time of the day or what season the experiment was performed. Michelson concluded that the earth must be dragging the ether along with it so that there was no wind detected, just like the earth drags the air around with it so that there are not thousand-mile per hour winds on the earth.

However, Einstein came to a different conclusion. He said that there was no detectable ether wind because, in effect, no matter when they performed the experiment, it was just as though they were stationary in the ether. This, of course, seemed to be a contradiction but Einstein was able to show that there was no contradiction.

[abrowaqas]

good reply...

but the contradiction part is not clear...

please tell me again that how Einstein theory of relativity is a reply to the MMX failure.

[ghwellsjr]

good reply...

but the contradiction part is not clear...

please tell me again that how Einstein theory of relativity is a reply to the MMX failure.
MMX was designed to measure the wind caused by moving through the ether. Einstein simply said that everytime they made a measurement,
they were not moving through the ether, therefore, there was no ether wind, it was exactly the same as being at rest in the ether.

In other words, what seemed to be a contradiction between MMX and Einstein turned out not to be.

[abrowaqas]

thanks

i got it now