Explanation of m&m experiment through sr

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Discussion Overview

The discussion revolves around the Michelson-Morley experiment and its implications regarding the existence of ether. Participants explore how the experiment might be interpreted from the perspective of an observer at rest in space, and they engage with various interpretations of the experiment's outcomes and the concept of inertial reference frames (IRF).

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants assert that the Michelson-Morley experiment demonstrated that ether does not exist, while others argue that it only failed to detect ether, which does not equate to proving its non-existence.
  • There is a discussion about how the experiment would appear in the IRF of an observer at rest in space, with some suggesting that the observer's state could influence the interpretation of the results.
  • One participant mentions that Einstein indicated the experimenters could consider themselves at rest, which would explain the lack of detected ether wind.
  • Another participant emphasizes that experiments do not prove theories but rather disprove competing theories, highlighting a nuanced understanding of scientific validation.
  • Several participants express confusion regarding the video content related to the experiment and its implications, indicating a need for clarification on the interpretations presented.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of the Michelson-Morley experiment regarding ether. There are multiple competing views on whether the experiment proves the non-existence of ether or simply fails to detect it.

Contextual Notes

Some participants note that both the observer and the system may not be in an IRF, leading to further questions about the implications of motion and reference frames on the experiment's outcomes.

Who May Find This Useful

This discussion may be of interest to those exploring the historical context of the Michelson-Morley experiment, the development of theories regarding ether, and the principles of reference frames in physics.

ash64449
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Hello friends,

We all know that Michelson-Morley conducted an experiment which led to the proof that ether doe not exist. I don't know whether there is an alternative experiment of this,if there is i mean this experiment(http://www.youtube.com/results?sear...46.1525.1j5j2j1.9.0...0.0...1ac.1.JO2rBQAXZaU , 4th link.)

What would Michelson-Morley Experiment look like in the IRF of an observer who is at rest(This observer will be in space)
 
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ash64449 said:
Hello friends,

We all know that Michelson-Morley conducted an experiment which led to the proof that ether doe not exist. I don't know whether there is an alternative experiment of this,if there is i mean this experiment(http://www.youtube.com/results?sear...46.1525.1j5j2j1.9.0...0.0...1ac.1.JO2rBQAXZaU , 4th link.)

What would Michelson-Morley Experiment look like in the IRF of an observer who is at rest(This observer will be in space)
They assumed that they were not at rest but Einstein pointed out that they could legitimately make that assumption and that would explain why they could not detect any ether wind. (They did not prove that ether does not exist. That's impossible.)
 
ghwellsjr said:
They assumed that they were not at rest but Einstein pointed out that they could legitimately make that assumption and that would explain why they could not detect any ether wind. (They did not prove that ether does not exist. That's impossible.)

see the 4th video. It said like that. And they said that ether does not exist.
 
ash64449 said:
see the 4th video. It said like that. And they said that ether does not exist.

i will take back this answer!
 
ghwellsjr said:
They assumed that they were not at rest but Einstein pointed out that they could legitimately make that assumption and that would explain why they could not detect any ether wind. (They did not prove that ether does not exist. That's impossible.)

watch that video.then they conducted the experiment in other way.they conducted experiment by thinking that they are moving opposite to ether wind.so light should have traveled slower speed and both would not have reached the the beam split mirror at the same time.but light traveled constant.so ether does not exist
 
ghwellsjr said:
They assumed that they were not at rest but Einstein pointed out that they could legitimately make that assumption and that would explain why they could not detect any ether wind. (They did not prove that ether does not exist. That's impossible.)

this is not my question.will the light reach at the same time in the beam splitter in the IRF frame of observer who is at rest.this guy should be outside Earth's orbit
 
Note that both the observer and the system are not in an IRF.
 
Passionflower said:
Note that both the observer and the system are not in an IRF.

why the observer? I said that he is out of the orbit so that he remains in rest.ok then.consider Earth as moving uniform motion with reference to that observer.then what change can we observe?
 
I am not on a system that can view videos right now. I'll take a look later when I get a chance.
 
  • #10
ghwellsjr said:
I am not on a system that can view videos right now. I'll take a look later when I get a chance.

yes.me too! That is why i gave that link instead of that video itself.but don't worry. You can open it with the help of your mobile. It works.
 
  • #11
ash64449 said:
why the observer? I said that he is out of the orbit so that he remains in rest.ok then.consider Earth as moving uniform motion with reference to that observer.then what change can we observe?
Sorry, I missed that, yes when the observer is in space he is in an IRF. By the way if he is in orbit he is also in an IRF.
 
  • #12
Passionflower said:
Sorry, I missed that, yes when the observer is in space he is in an IRF. By the way if he is in orbit he is also in an IRF.

yes.. Ok. I know. When you said like that,i itself got confused.. Now can you give me answer? And can you see the video that i said?
 
  • #13
ash64449 said:
We all know that Michelson-Morley conducted an experiment which led to the proof that ether does not exist.

You'll hear people saying this all the time. They're being sloppy.

The MM experiment demonstrated that we do not observe certain effects that are predicted by the most common and simplest class of ether theories, and therefore that those theories could not be correct.


(In general, any time that you hear someone say that an experiment "proves" something, they're being a bit sloppy. Experiments don't prove theories, they disprove competing theories).
 
  • #14
ash64449 said:
Hello friends,

We all know that Michelson-Morley conducted an experiment which led to the proof that ether doe not exist. I don't know whether there is an alternative experiment of this,if there is i mean this experiment(http://www.youtube.com/results?sear...46.1525.1j5j2j1.9.0...0.0...1ac.1.JO2rBQAXZaU , 4th link.)

What would Michelson-Morley Experiment look like in the IRF of an observer who is at rest(This observer will be in space)

"absence of evidence is not evidence of absence"
 
  • #15
ash64449 said:
Hello friends,

We all know that Michelson-Morley conducted an experiment which led to the proof that ether doe not exist. I don't know whether there is an alternative experiment of this,if there is i mean this experiment(http://www.youtube.com/results?sear...46.1525.1j5j2j1.9.0...0.0...1ac.1.JO2rBQAXZaU , 4th link.)

What would Michelson-Morley Experiment look like in the IRF of an observer who is at rest(This observer will be in space)
Everytime I click on the video link, I get a different set of videos so I"m not sure which is the one you want but I think it is the one with the serial number XavC4w_Y9b8.

My comments will be with regard to that video. You have to pay real close attention to what they said. They never said that MMX proved that ether does not exist. At around 6:50 into the video they said "in complete disagreement with the idea of Earth moving through the ether". Then at 7:15 they say "the experiment had failed to detect the ether". This is different than saying they proved the ether does not exist.

As I said earlier, Einstein showed that no matter what inertial state they were in, they could consider themselves to be at rest with the respect to the ether. So the experiment would have the same result even if they were in a legitimate IRF but I'd hate to be around all the mercury in a weightless environment.

I think I'm totally missing the significance of your question.
 
  • #16
Nugatory said:
Experiments don't prove theories, they disprove competing theories).
Well stated.
 
  • #17
A regular M&M is a peanut M&M moving very fast.
 
  • #18
ghwellsjr said:
Everytime I click on the video link, I get a different set of videos so I"m not sure which is the one you want but I think it is the one with the serial number XavC4w_Y9b8.

My comments will be with regard to that video. You have to pay real close attention to what they said. They never said that MMX proved that ether does not exist. At around 6:50 into the video they said "in complete disagreement with the idea of Earth moving through the ether". Then at 7:15 they say "the experiment had failed to detect the ether". This is different than saying they proved the ether does not exist.

As I said earlier, Einstein showed that no matter what inertial state they were in, they could consider themselves to be at rest with the respect to the ether. So the experiment would have the same result even if they were in a legitimate IRF but I'd hate to be around all the mercury in a weightless environment.

I think I'm totally missing the significance of your question.
I mean this video :
 
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  • #19
Nugatory said:
You'll hear people saying this all the time. They're being sloppy.

The MM experiment demonstrated that we do not observe certain effects that are predicted by the most common and simplest class of ether theories, and therefore that those theories could not be correct.


(In general, any time that you hear someone say that an experiment "proves" something, they're being a bit sloppy. Experiments don't prove theories, they disprove competing theories).

Yes.you are right. Experiments disprove two conflicting theories.. Thank you for your response!
 
  • #20
ghwellsjr said:
Everytime I click on the video link, I get a different set of videos so I"m not sure which is the one you want but I think it is the one with the serial number XavC4w_Y9b8.

My comments will be with regard to that video. You have to pay real close attention to what they said. They never said that MMX proved that ether does not exist. At around 6:50 into the video they said "in complete disagreement with the idea of Earth moving through the ether". Then at 7:15 they say "the experiment had failed to detect the ether". This is different than saying they proved the ether does not exist.

As I said earlier, Einstein showed that no matter what inertial state they were in, they could consider themselves to be at rest with the respect to the ether. So the experiment would have the same result even if they were in a legitimate IRF but I'd hate to be around all the mercury in a weightless environment.

I think I'm totally missing the significance of your question.

I would like to understand this: Since Earth is moving, time slows down(moving with respect to observer who is outside the earth). When time slows down, There will be change in simultaneous events. Like they conducted experiment like this: They sent a beam,splits into two when encountered beam splitter (I think that is a beam splitter) One travels perpendicular to it,other goes straight.they too hit the two mirrors at the same time and come back to the beam splitter. This happened to them. So i wanted to ask this: Will those two split light hit the two mirrors at the same time in reference to observer outside Earth's orbit? But i think even this happens,it will reach the beam split mirror at the same time.
 
  • #21
ghwellsjr said:
Everytime I click on the video link, I get a different set of videos so I"m not sure which is the one you want but I think it is the one with the serial number XavC4w_Y9b8.

My comments will be with regard to that video. You have to pay real close attention to what they said. They never said that MMX proved that ether does not exist. At around 6:50 into the video they said "in complete disagreement with the idea of Earth moving through the ether". Then at 7:15 they say "the experiment had failed to detect the ether". This is different than saying they proved the ether does not exist.

As I said earlier, Einstein showed that no matter what inertial state they were in, they could consider themselves to be at rest with the respect to the ether. So the experiment would have the same result even if they were in a legitimate IRF but I'd hate to be around all the mercury in a weightless environment.

I think I'm totally missing the significance of your question.

ash64449 said:
I mean this video :

You are correct. That video does very clearly state that the M&M "experiment allows us to conclude that the ether frame does not exist". However, that is not a correct conclusion. This video is full of errors and I would classify it as pure propaganda.

For example, they state that the two legs of the experiment are the same length and only when the light travels exactly the same distance for the two paths taking exactly the same time will there be no interference. If light travels at different speeds in the two legs, then an interference pattern will be observed, they claim. This is totally wrong. First off, it's impossible to make the two legs exactly the same and even if they did, there would still be an interference pattern. (It's called an interferometer.) So in reality, what M&M were concerned about is whether the interference pattern changes while the apparatus floating on the mercury is slowly rotated.

Even the other video gets this wrong. They said there should be a bright spot in the middle of the pattern if the light signals take the same time and constructively interfere and a dark spot in the middle if the beams take a different time and destructively interfere. Total nonsense.

Notice another really significant difference between the two videos. In the one you preferred, they made the statement that if the apparatus were moving along the direction of the initial beam, then the beam would take longer along the perpendicular path because it had longer to go due to Pythagorean triangle. The other video says that the parallel path is the one that takes longer (they are correct).

So you can't trust popular explanations just because they make snazzy videos.
ash64449 said:
I would like to understand this: Since Earth is moving, time slows down(moving with respect to observer who is outside the earth). When time slows down, There will be change in simultaneous events. Like they conducted experiment like this: They sent a beam,splits into two when encountered beam splitter (I think that is a beam splitter) One travels perpendicular to it,other goes straight.they too hit the two mirrors at the same time and come back to the beam splitter. This happened to them. So i wanted to ask this: Will those two split light hit the two mirrors at the same time in reference to observer outside Earth's orbit? But i think even this happens,it will reach the beam split mirror at the same time.
It is not important to determine the simultaneity of the light beams hitting the various mirrors and beam splitter. We cannot know that information. The only thing that is important is whether the interference pattern changes as the apparatus is rotated. And as long as the experiment is conducted close to an inertial state, the pattern does not change enough to notice. It wouldn't make any difference if the apparatus were traveling at 0.999c with respect to the proposed ether or at rest in the ether.

As I said before, prior to Einstein, Lorentz and others explained the null result by claiming that the lengths of things contracted along the direction of motion through the ether and that's why they did not detect any change in the interference pattern but Einstein pointed out that they could just as easily consider the apparatus to be stationary in the ether and experience no length contraction whereas anything that was "actually" stationary in the ether would be length contracted.

Remember what you learned from DaleSpam? All the effects of Special Relativity are "vice versa" and it doesn't matter which frame you consider to be your rest frame so if you pick one in which the apparatus is at rest, there will be no length contraction. Got it?
 
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  • #22
ghwellsjr said:
You are correct. That video does very clearly state that the M&M "experiment allows us to conclude that the ether frame does not exist". However, that is not a correct conclusion. This video is full of errors and I would classify it as pure propaganda.

For example, they state that the two legs of the experiment are the same length and only when the light travels exactly the same distance for the two paths taking exactly the same time will there be no interference. If light travels at different speeds in the two legs, then an interference pattern will be observed, they claim. This is totally wrong. First off, it's impossible to make the two legs exactly the same and even if they did, there would still be an interference pattern. (It's called an interferometer.) So in reality, what M&M were concerned about is whether the interference pattern changes while the apparatus floating on the mercury is slowly rotated.

Even the other video gets this wrong. They said there should be a bright spot in the middle of the pattern if the light signals take the same time and constructively interfere and a dark spot in the middle if the beams take a different time and destructively interfere. Total nonsense.

Notice another really significant difference between the two videos. In the one you preferred, they made the statement that if the apparatus were moving along the direction of the initial beam, then the beam would take longer along the perpendicular path because it had longer to go due to Pythagorean triangle. The other video says that the parallel path is the one that takes longer (they are correct).

So you can't trust popular explanations just because they make snazzy videos.

It is not important to determine the simultaneity of the light beams hitting the various mirrors and beam splitter. We cannot know that information. The only thing that is important is whether the interference pattern changes as the apparatus is rotated. And as long as the experiment is conducted close to an inertial state, the pattern does not change enough to notice. It wouldn't make any difference if the apparatus were traveling at 0.999c with respect to the proposed ether or at rest in the ether.

As I said before, prior to Einstein, Lorentz and others explained the null result by claiming that the lengths of things contracted along the direction of motion through the ether and that's why they did not detect any change in the interference pattern but Einstein pointed out that they could just as easily consider the apparatus to be stationary in the ether and experience no length contraction whereas anything that was "actually" stationary in the ether would be length contracted.

Remember what you learned from DaleSpam? All the effects of Special Relativity are "vice versa" and it doesn't matter which frame you consider to be your rest frame so if you pick one in which the apparatus is at rest, there will be no length contraction. Got it?

yes.
 
  • #23
Here is a set of animations that I made along with a detailed explanation that you might find interesting.
 
  • #24
ash64449 said:
yes.

yes.i got it. That every reference frame is not unique. Results would come out to be same. Why they introduced length contraction and all because they told ether as absolute reference frame.

But eventough results are same,but simulatneous events do change. Didn't you and DaleSpam told like that? If in one reference frame events are simultaneous,in other reference frame events are not simultaneous and vice versa. These simultaneous events change.

So that video is wrong.can you tell me the real experiment?
 
  • #25
ash64449 said:
yes.i got it. That every reference frame is not unique. Results would come out to be same. Why they introduced length contraction and all because they told ether as absolute reference frame.

But eventough results are same,but simulatneous events do change. Didn't you and DaleSpam told like that?
When we speak of simultaneity, we are talking about the time coordinates of two events in a particular frame. So we wouldn't want to say "simultaneous events" but rather events that are simultaneous in this particular frame.
ash64449 said:
If in one reference frame events are simultaneous,in other reference frame events are not simultaneous and vice versa. These simultaneous events change.

So that video is wrong.can you tell me the real experiment?
Here, I'll let M&M tell you.
 
  • #26
ghwellsjr said:
When we speak of simultaneity, we are talking about the time coordinates of two events in a particular frame. So we wouldn't want to say "simultaneous events" but rather events that are simultaneous in this particular frame.

Here, I'll let M&M tell you.

Actually by simultaneous events,i meant simultaneous event in particular frame.. I did understood your point clearly.
 

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