# Michelson-Morley Experiment

The Michelson-Morley experiment tried to find a made-up material called the luminiferous aether that scientists thought was all around us and helped light move. Even though the experiment didn't work, it's still famous because of what we learned from it. To understand why it's famous, we need to look closer at what happened during the experiment. It's also called the "most famous failed experiment."

## What is the Michelson-Morley experiment?

The Michelson-Morley experiment aimed to figure out how things move through the imaginary luminiferous aether. They did this by measuring the speed of light in different directions. They discovered that the speed of light was the same in every direction. This meant that there was no such thing as aether. This was a big deal because it went against what scientists believed at the time. The experiment led to the theory of special relativity which explained things in a different way and showed that aether doesn't exist.

### The purpose of the experiment

In the 1800s, scientists believed that light waves needed a material, called luminiferous aether, to help them move, just like sound and water waves need a medium to travel. They even thought that a vacuum, or empty space, had to be filled with aether since light can move through it.

In 1886, Michelson and Morley confirmed Fresnel's drag coefficient, which showed how a moving medium affects light. This coefficient was seen as proof that aether was stationary.

The experiment used an interferometer, an optical tool that compares the length of light paths in two directions.

Michelson suggested that if they compared the speed of light in the direction of the Earth's movement and the speed of light at an angle to Earth's rotation, they could find a difference. This difference would prove that light's speed changes depending on if it moves through aether or not. But the experiment showed no difference between the two speeds.

### The outcome of the experiment

Since the outcome was negative, they disproved their theories and the aether theories which came before them. Instead, the results of the experiment proved that there is no difference between the speed of light while traveling in different directions.

The Michelson-Morley experiment was conducted in 1880-81 by the physicist A.A. Michelson and refined in 1887 by Michelson and Edward W. Morley in the United States. The experiment was an attempt to detect the velocity of Earth with respect to the hypothetical luminiferous ether, a medium in space proposed to carry light waves. The experiment involved the use of an interferometer, which featured perpendicular arms. Michelson and Morley observed that light traveled faster along an arm which was oriented in the same direction as the ether. The light traveled at a slower pace in the arm oriented in the opposite direction.

## Why is it known as “the most famous failed experiment”?

### Impact on the theory of special relativity

Albert Einstein's paper in 1905 provided an explanation for the puzzling results of the Michelson-Morley experiment. He claimed that there was no such thing as the luminiferous aether, as light is a special type of wave that does not require a medium to propagate through. Without the aether, there is no preferred frame of reference, and measurements of the speed of light are always the same, regardless of the motion of the observer.

Einstein's realization that the Michelson-Morley experiment was not a failure but rather a significant step in the development of physics led him to formulate his theory of special rel. This theory fundamentally changed our understanding of space and time and introduced the concept of the speed of light as a constant that cannot be exceeded.

The Michelson-Morley experiment is considered one of the most important experiments in the history of physics, as it provided crucial evidence against the aether hypothesis and paved the way for new discoveries in the field of relativity.

## Michelson-Morley Experiment

When did the Michelson-Morley experiment take place?

The experiment took place in 1887.

What was the purpose of the Michelson-Morley experiment?

The purpose of the Michelson-Morley experiment was to prove the existence of luminiferous aether.

What is the conclusion of the Michelson-Morley experiment?

The inevitable conclusion was that, after all, there was no aether. Einstein's theory about the speed of light being a universal constant to which no motion could be added was backed up by this conclusion.

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