[oneshtein]

Michelson-Morley experiment found no changes in speed of light at all. Nothing. Zero fluctuations.

These fluctuations of speed of light were found much later, by LIGO/VIRGO and NANOGrav.

The flaw of Michelson-Morley experiment is that it was performed in isolated environment, but tried to measure an external effect.

Imagine that we want to measure atmospheric circulation in the same way: by measuring speed of wind in an closely isolated and insulated room: it's impossible.

However, Michelson-Morley experiment is one of corner stones for theory of Relativity.

> This incongruous result puzzled the physicists of the world until 1905 when Einstein published his theory of relativity. Viewed in the light of Einstein's revolutionary work, the null results of the Michelson-Morley experiment were not only predictable, but provided experimental confirmation of Einstein's theory.

[less_less]

I don't agree with this characterization. This is not to say that foundational studies are never invalidated: I just don't think MM was one of them.

> Michelson-Morley experiment found no changes in speed of light at all. Nothing. Zero fluctuations.

The MM experiment aimed to observe a predicted effect of the theory of luminiferous aether, which would have enabled measuring the Earth's speed relative to a canonical reference frame (the aether). It was sufficiently precise to observe that predicted effect but did not observe it, which provided strong evidence that the aether theory was wrong.

Finding that any variation in the propagation of light was too small to be detected by their instruments (and too small to be consistent with aether theory) is not the same as finding that it's exactly zero.

> These fluctuations of speed of light were found much later, by LIGO/VIRGO and NANOGrav.

It's not the same fluctuations though: these experiments found much smaller fluctuations than MM looked for, from a different effect. They're not even (understood to be) fluctuations in c, but in the shape of space.

> The flaw of Michelson-Morley experiment is that it was performed in isolated environment, but tried to measure an external effect.

The later interferometer experiments (LIGO and VIRGO) are conceptually very similar to the original MM experiment. The environment is not fundamentally different, and on the contrary LIGO and VIRGO are better isolated (against ordinary vibrations: we don't know any way to isolate an experiment from gravitational waves). They're just much larger and more precise, which is why they can observe the much smaller effect of gravitational waves.

> However, Michelson-Morley experiment is one of corner stones for theory of Relativity.

Yes, but the effects observed by LIGO and VIRGO are predicted by general relativity, which is what inspired scientists to carry out those experiments. As far as I know, they are consistent with GR to the extent that LIGO and VIRGO have measured them.

[oneshtein]

> The MM experiment aimed to observe a predicted effect of the theory of luminiferous aether ... which provided strong evidence that the aether theory was wrong.

MM failed to observe effects predicted by theory of STATIC luminiferous aether. It looks like there is no absolute aether frame (which will be strange to have in the infinite Universe).

> They're just much larger and more precise, which is why they can observe the much smaller effect of gravitational waves.

Yep. We can discard MM experiment now, because LIGO/Virgo is much better.

If we want to measure wind at high altitude, but we put our measurement tool deep and isolated it well, with high enough precision, we will be able to measure distant earthquakes and nuclear explosions. No luck with wind, of course.

To catch the wind, we need something like NANOgrav, but at much smaller scale at high orbit around Earth. Luckily, we have large number of GPS satellites with high-precision clocks in the sky: https://link.springer.com/article/10.1007/s10291-017-0686-6 . I see strong annual signal here.

> Yes, but the effects observed by LIGO and VIRGO are predicted by general relativity

This doesn't make GR unique. Other theories can predict this too. It's just waves in a medium. However, GR is abstract theory, which lacks explanation power. Lack of explanation causes lack of understanding.

[sinuhe69]

Michelson’s experiments only proved there is no “Aether”, a supposedly invisible medium to carriers light. It also proved that the speed of light isn’t affected by (relative) movements. In some sense, yes one can say the speed of light of is constant. But in the context of the cosmos, it strictly doesn’t say anything about the speed of light in the past.

[zmgsabst]

LIGO proved there is an aether and density ripples in it change the distance that light travels — as shown by a characteristic oscillation generated by dense objects colliding causing interference between the arms of LIGO.

The reason MM failed to show that light changes speed is because we’re not moving through the aether, but are ourselves aether stuff — and so our own perspective gets equally warped. Since us and the light both change with the relative motion, we can’t see the change.

[oneshtein]

However, LIGO, VIRGO, and NANOGrav experiments and observations proved that speed of light in vacuum is NOT constant, which makes Michelsons's experiment obsolete.

[i_no_can_eat]

The LIGO/VIRGO experiments proved no such thing. You seem to have a fundamentally flawed understanding of these experiments.

That the speed of light is constant in vacuum is one of the fundamental assumptions of general relativity. The results of LIGO/VIRGO are so far fully compatible with GR.

[oneshtein]

^ This is the problem we are looking for in this discussion.

[i_no_can_eat]

The problem in this discussion is that you don't have an understanding of the concepts involved. You haven't properly understood the LIGO experiments and you clearly know nothing of general relativity. There really is no point in continuing this further.

[oneshtein]

It doesn't looks like you wanted to discuss flaws in GR with a dissident, who, obviously, too stupid to understand GR and SR. You told me that. You did the job. Now, «shut up and calculate».