Ask Ethan # 29: The Most Famous Failed Experiment
In 1887, two scientists decided to measure how the motion of the Earth affects the speed of light. What they did not discover changed the world as a result.
We love scientific success - people, experiments and theories that tell about new phenomena, the laws of physics and the ways of the origin of the Universe. But these achievements are not born in a vacuum. They occur because there is a need to invent something new when our current ideas can no longer explain a certain phenomenon or result. This week's question:
I did not write, but I had to. Let's go back to the beginning of the second half of the 19th century.
')
Gravity was the first of the studied forces, when Newton put forward his law of universal perception in the 17th century. He explained the movement of bodies on Earth and in space. After a few decades, in 1704, he also advanced the corpuscular theory of light, which claimed that light consists of particles, that they are solid and have no mass, and that they move in a straight line, unless something causes them to reflect. refracted or diffracted.
This explained many observations, in particular, that white light is a combination of many others. But over time, experiments have shown the wave nature of light, confirming an alternative explanation from contemporary of Newton, Christian Huygens.
Huygens suggested that every point that can be considered a source of light, including all points of a moving rectilinear wave, behaves like a wave with a spherical front emanating from each of these points. And although many experiments were consistent with both theories, some of them, conducted in 1799, began to demonstrate the power of the wave theory.
By isolating different colors and passing them through single and double slots or grids, scientists observed pictures that can be obtained only in the case of the wave nature of light, which behaved like waves on water.
But, as you know, the waves move in the water. If you remove the water, there will be no waves. This was equally true for all known phenomena: for example, sound also requires an environment for movement. If you remove all the matter, there is no medium for sound - hence the expression “No screams are heard in space”.
Therefore, since light is a wave, although electromagnetic, as Maxwell demonstrated in the 1860s, it must also have an environment through which it propagates. No one could find her, but she was still given a name: the luminiferous ether.
Now that sounds silly, isn't it? But the idea was not bad in itself. She had all the signs of a great scientific idea, since she was not only built on previous scientific achievements, but she also issued predictions that could be tested.
Imagine throwing a rock into a river and watching the waves. Waves going towards the coast will move at a certain speed.
And what about the upstream waves? They will move more slowly, because the environment on which they move, that is, the water - is moving! And the waves moving downstream will move faster for the same reason.
And although the luminiferous ether has never been discovered, a brilliant experiment developed by Albert Michelson, who applied the same principle to the light, was proposed.
Although we did not know how the ether is oriented in space, what its direction is and how it moves, or that it rests in relation to it - we could assume that it is absolute. It exists independently of matter, since light can move in a vacuum.
Therefore, in principle, by measuring the speed at which the light moves when the Earth moves “downstream” or “against” (or perpendicular to the flow of the ether), you can not only detect the existence of the ether, but also find a fixed coordinate system of the Universe! Unfortunately, the light travels at a speed of 186282 miles per second (and Michelson believed that at a speed of 186350 ± 30 miles per second), and the Earth's orbital speed is only 18.5 miles per second. In the 1880s such speeds were difficult to measure.
But Michelson came up with a trick.
In 1881, he developed an ingenious device, now known as a Michelson interferometer. His principle was based on the fact that light consisting of waves interferes with itself. If we take a light wave, we divide it into two perpendicular components (which, therefore, will move differently with respect to the ether), and hold them at an equal distance, and then reflect back to each other, we will observe a shift in the interference pattern which they will create.
If the whole device is stationary in relation to the ether, there should be no shift in the interference pattern, but if it moves in one direction differently than in the other, then we will get a shift.
The original device could not determine the shift - but with a path length of 1.2 meters, the shift should have amounted to 0.04 interference band, which exceeded the limit of what he could measure with his instruments (the limit was about 0.02). There was also the idea that the ether rests - for example, that the Earth carries him along (although it could not be absolutely static, observations of stellar aberrations spoke about this), so he conducted the experiment many times a day, because the rotating Earth should have been differently located in relation to the ether.
The lack of results did not convince. Over the next six years, he developed an interferometer 10 times larger and 10 times more accurate with Edward, and the two of them conducted a new experiment in 1887, which became known as the Michelson-Morley experiment. They expected an interference shift of 0.4 with a measurement accuracy of 0.01.
And thanks to the Internet, you can find the original measurement results:
The absence of a result, which showed that no luminiferous ether exists, was a big step in science. It meant that the light must be fundamentally different from all other known waves. The solution was found 18 years later, when Einstein's special theory of relativity appeared. Along with it, it came to the understanding that the speed of light is a universal constant in all reference systems, there was no absolute time or absolute space, and that light only needed space and time to move.
The experiment, and the work of Michelson, were so revolutionary that he, as far as I know, became the only person in history who won the Nobel Prize for the very precise absence of the discovery of anything!
Conclusions, very strange conclusions, arise with surprising ease: proof is indisputable. But at the same time it looks as if he has achieved results only by the power of his thought, not listening to the opinions of others. That is what he did.
- Snow on the work of Einstein from 1905.
We love scientific success - people, experiments and theories that tell about new phenomena, the laws of physics and the ways of the origin of the Universe. But these achievements are not born in a vacuum. They occur because there is a need to invent something new when our current ideas can no longer explain a certain phenomenon or result. This week's question:
Did you write anything about Michelson-Morley's “The Most Famous Failed Experiment?” It seems to me that it is very important for understanding the development of science, and he began a wave of research that led to quantum mechanics and a special theory of relativity.
I did not write, but I had to. Let's go back to the beginning of the second half of the 19th century.
')
Gravity was the first of the studied forces, when Newton put forward his law of universal perception in the 17th century. He explained the movement of bodies on Earth and in space. After a few decades, in 1704, he also advanced the corpuscular theory of light, which claimed that light consists of particles, that they are solid and have no mass, and that they move in a straight line, unless something causes them to reflect. refracted or diffracted.
This explained many observations, in particular, that white light is a combination of many others. But over time, experiments have shown the wave nature of light, confirming an alternative explanation from contemporary of Newton, Christian Huygens.
Huygens suggested that every point that can be considered a source of light, including all points of a moving rectilinear wave, behaves like a wave with a spherical front emanating from each of these points. And although many experiments were consistent with both theories, some of them, conducted in 1799, began to demonstrate the power of the wave theory.
By isolating different colors and passing them through single and double slots or grids, scientists observed pictures that can be obtained only in the case of the wave nature of light, which behaved like waves on water.
But, as you know, the waves move in the water. If you remove the water, there will be no waves. This was equally true for all known phenomena: for example, sound also requires an environment for movement. If you remove all the matter, there is no medium for sound - hence the expression “No screams are heard in space”.
Therefore, since light is a wave, although electromagnetic, as Maxwell demonstrated in the 1860s, it must also have an environment through which it propagates. No one could find her, but she was still given a name: the luminiferous ether.
Now that sounds silly, isn't it? But the idea was not bad in itself. She had all the signs of a great scientific idea, since she was not only built on previous scientific achievements, but she also issued predictions that could be tested.
Imagine throwing a rock into a river and watching the waves. Waves going towards the coast will move at a certain speed.
And what about the upstream waves? They will move more slowly, because the environment on which they move, that is, the water - is moving! And the waves moving downstream will move faster for the same reason.
And although the luminiferous ether has never been discovered, a brilliant experiment developed by Albert Michelson, who applied the same principle to the light, was proposed.
Although we did not know how the ether is oriented in space, what its direction is and how it moves, or that it rests in relation to it - we could assume that it is absolute. It exists independently of matter, since light can move in a vacuum.
Therefore, in principle, by measuring the speed at which the light moves when the Earth moves “downstream” or “against” (or perpendicular to the flow of the ether), you can not only detect the existence of the ether, but also find a fixed coordinate system of the Universe! Unfortunately, the light travels at a speed of 186282 miles per second (and Michelson believed that at a speed of 186350 ± 30 miles per second), and the Earth's orbital speed is only 18.5 miles per second. In the 1880s such speeds were difficult to measure.
But Michelson came up with a trick.
In 1881, he developed an ingenious device, now known as a Michelson interferometer. His principle was based on the fact that light consisting of waves interferes with itself. If we take a light wave, we divide it into two perpendicular components (which, therefore, will move differently with respect to the ether), and hold them at an equal distance, and then reflect back to each other, we will observe a shift in the interference pattern which they will create.
If the whole device is stationary in relation to the ether, there should be no shift in the interference pattern, but if it moves in one direction differently than in the other, then we will get a shift.
The original device could not determine the shift - but with a path length of 1.2 meters, the shift should have amounted to 0.04 interference band, which exceeded the limit of what he could measure with his instruments (the limit was about 0.02). There was also the idea that the ether rests - for example, that the Earth carries him along (although it could not be absolutely static, observations of stellar aberrations spoke about this), so he conducted the experiment many times a day, because the rotating Earth should have been differently located in relation to the ether.
The lack of results did not convince. Over the next six years, he developed an interferometer 10 times larger and 10 times more accurate with Edward, and the two of them conducted a new experiment in 1887, which became known as the Michelson-Morley experiment. They expected an interference shift of 0.4 with a measurement accuracy of 0.01.
And thanks to the Internet, you can find the original measurement results:
The absence of a result, which showed that no luminiferous ether exists, was a big step in science. It meant that the light must be fundamentally different from all other known waves. The solution was found 18 years later, when Einstein's special theory of relativity appeared. Along with it, it came to the understanding that the speed of light is a universal constant in all reference systems, there was no absolute time or absolute space, and that light only needed space and time to move.
The experiment, and the work of Michelson, were so revolutionary that he, as far as I know, became the only person in history who won the Nobel Prize for the very precise absence of the discovery of anything!
Source: https://habr.com/ru/post/366367/
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