# Maxwell's idea to measure aether

• ghwellsjr
In summary, Maxwell proposed using the observation of eclipses of Jupiter's satellites at opposite points on the ecliptic to determine the relative velocity of the aether with respect to the solar system. This method would involve comparing the values of the velocity of light at these two points and the difference in these values would be twice the speed of the Earth through the aether. It is possible that Maxwell's experiment could have yielded a null result, indicating that the Earth's motion through the aether was too small to measure accurately. However, it is unclear if Maxwell's proposal was simply to repeat Römer's experiment with greater accuracy or if he had a different approach in mind.
ghwellsjr
Gold Member
On this webpage http://www.mathpages.com/home/kmath241/kmath241.htm" are these words of Maxwell:

"The only practicable method of determining directly the relative velocity of the aether with respect to the solar system is to compare the values of the velocity of light deduced from the observation of the eclipses of Jupiter’s satellites when Jupiter is seen from the Earth at nearly opposite points of the ecliptic."

First off, has this been discussed on this forum?

Secondly, what exactly was Maxwell proposing?

And finally, assuming that the technology were available to Maxwell, could he have measured something that would have led him to the wrong conclusion?

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Assuming that the Earth has a specific speed through the ether, then measuring the speed of light coming from Jupiter (or any object) at opposite points on the ecliptic would, under the right conditions, give values differing by twice the speed of the Earth through the ether. Since Michaelson and Morley did similar experiment not long after (on the surface of the earth, not using Jupiter) I imagine that the technology was sufficient (certainly people were getting accurate values for the speed of light using the eclipses of the moons of Jupiter). What he would have gotten would, of course, have been a null result- that the motion of the Earth through the ether, if any, was too small to measure.

I guess I should have asked a more detailed question. Let me provide some more background and try to get at what I am looking for.

Maxwell's idea was to measure the one-way speed of light at two different times, one when the Earth was moving toward to Jupiter and six months later when the Earth was moving away from Jupiter. MMX measured the difference in the speed of light between two round-trip paths at the same time but in two different directions 90 degrees apart. Their experiment was actually practicable and I fully understand it but I'm not sure Maxwell's was because I don't fully understand what he was proposing.

I think maybe what Maxwell was proposing basically amounted to observing a distant clock and measuring the time interval between "ticks" of that clock when moving toward it and then when moving away from it and calculating the speed of light, knowing the distance that the light traveled in both cases, taking the difference. But I don't know how he could know the distance accurately enough to draw any conclusion and I don't know if this would even work in principle.

So maybe his idea was that he would have a stable clock on Earth and what he wanted to measure was the "drift" in the tick rate the distant clock as the Earth moved toward it and then away from it.

So what I'm looking for is a detailed explanation of what he was proposing to measure and what he was hoping to conclude and if his experiment could have measured something that would have lead him to a false conclusion, again assuming that he had even more precise instruments than we have today.

Recall that Römer first calculated (an estimate of) the speed of light by comparing the timing of Jupiter's eclipses when the line of sight from the Earth to Jupiter is across the Earth's orbit (i.e. when Jupiter and the Earth are more or less "furthest" from each other), versus when the line of sight is in the opposite direction (i.e. when Jupiter and the Earth are more or less "closest" to each other).

I suspect that Maxwell's suggestion meant to repeat this procedure twice, with lines of sight at right angles to each other. This would (hypothetically) give different speeds of light for the two directions, relative to the solar system.

http://en.wikipedia.org/wiki/R%C3%B8mer%27s_determination_of_the_speed_of_light"

If I understand it correctly, the observations of Jupiter's moon can only be done near the the 90 degree points already, in other words, as per your second suggestion (at right angles to the first suggestion) and it was no where near accurate enough for Maxwell to have used Römer's data.

But you bring up a good point: was Maxwell simply proposing to repeat Römer's experiment with greater accuracy or did he want to do something different?

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## 1. What is Maxwell's idea to measure aether?

Maxwell's idea to measure aether was based on the concept that aether is a medium that permeates all of space and is responsible for the propagation of electromagnetic waves. He proposed using a device called an "aether wind" apparatus to detect the motion of aether.

## 2. How did Maxwell's idea contribute to the development of modern physics?

Maxwell's idea of aether helped lay the foundation for the theory of electromagnetism and the understanding of how light and other electromagnetic waves propagate through space. It also led to the development of the theory of relativity, as scientists began to question the existence of aether and its role in the universe.

## 3. Was Maxwell's idea of aether widely accepted by the scientific community?

Initially, Maxwell's idea of aether was widely accepted by the scientific community as it provided a plausible explanation for the behavior of electromagnetic waves. However, as more experiments were conducted, it became clear that aether did not exist and the theory was eventually replaced by the theory of relativity.

## 4. How did the aether wind apparatus work?

The aether wind apparatus consisted of a light source, a beam splitter, and two mirrors. The beam of light would be split into two beams, one traveling along the direction of the aether wind and the other perpendicular to it. The beams would then be reflected back to the beam splitter and recombined. If the aether wind was present, it would cause a slight difference in the speed of the two beams, resulting in an interference pattern that could be measured.

## 5. What impact did Maxwell's idea have on the understanding of the nature of light?

Maxwell's idea of aether helped to solidify the understanding of light as an electromagnetic wave. It also led to the discovery of other forms of electromagnetic radiation, such as radio waves and X-rays. Additionally, it paved the way for the development of quantum mechanics, which further advanced the understanding of light as both a wave and a particle.

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