I want to ask about a specific aspect; do we move relative to the EM field? Can we design an experiment similar to the Michaelson Morley experiment to measure our velocity relative to the EM field? If not, why? After researching a lot it seems to me the only answer is "don't ask this question" or "this question has no meaning" or "there is an answer but it is too technical for you"
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$\begingroup$ it seems we cannot en.wikipedia.org/wiki/…. We can only measure acceleration relative to the EM field $\endgroup$– UmaxoCommented Jul 19, 2021 at 4:58
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3 Answers
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All particle physics experiments depend on Lorentz transformations which describe perfectly electric and magnetic fields and how they transform with changes in velocity. No false results have been detected and so Lorenz transformation calculation are trusted to give changes due to to velocity, see page three here, also here for the electric field of a point charge.
Is there any difference between ether and EM field?
The luminiferous ether was proved not to be LOrentz covariant with the MM experiment. The electric and magnetic fields are covariant and allow the correct modeling of electromagnetic effects.
The luminiferous aether as hypothesized before the Michelson-Morley experiment was discarded as a concept because it was not Lorentz covariant, as was necessary for the Maxwell equations to work correctly. Up to now Maxwell equations are continually validated.
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do we move relative to the EM field?
No we do not. The electromagnetic field permeates all of space and it does not move. Electromagnetic waves do move at the speed given by $c$ and for every observer, this speed is always the same. Of course one can refer to an electromagnetic wave as an oscillating electric and magnetic field, but again these move with speed $c$ in all frames, so your question still would not apply.
Can we design an experiment similar to the Michaelson Morley experiment to measure our velocity relative to the EM field? If not, why?
The Michelson-Morley experiment attempted to determine if electromagnetic waves, or light, and not the electromagnetic field$^1$, required a medium called "ether" to propagate through, and it was found (and confirmed in more experiments) that such an ether does not exist. The electromagnetic field and the "ether" are two separate things.
Again, the electromagnetic field does not move. Electromagnetic waves are travelling excitations of the electromagnetic field.
After researching a lot it seems to me the only answer is "don't ask this question" or "this question has no meaning"
This is because no such thing as the "ether" exists, and as pointed out, this has been verified experimentally.
$^1$The concept of the electromagnetic field as it is known today, was not during the time of the Michelson-Morley experiment.
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$\begingroup$ What about the detection of motion with respect to the CBR? $\endgroup$ Commented Jul 19, 2021 at 5:34
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$\begingroup$ Hmm. No, the OP is of the opinion that the electromagnetic field is somehow in motion. $\endgroup$– joseph hCommented Jul 19, 2021 at 5:37
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$\begingroup$ Strictly speaking, CBR is an EM field. And we can measure our velocity wrt the reference frame where it is isotropic. Therefore, CBR seems to break the equivalence of the reference frames on a global scale. Probably, a discussion of such an issue could be useful, in 2021. $\endgroup$ Commented Jul 19, 2021 at 5:55
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$\begingroup$ @josephh It is amazing how sure you are that there is no medium. That fact that we are not able to detect it yet shouldn't allow us to be absolute about it's non existence. In quantum physics, "empty space" is far from being truly empty. All has started from the postulate of the constancy of the one way speed of light that we have no experimental proof. The only experimental proof we have is the constancy of the two way speed of light which doesn't rule out the existence of a light medium. This is one more "don't ask this question" answer. $\endgroup$ Commented Dec 29, 2023 at 12:34
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$\begingroup$ @MariosMourelatos It is amazing how sure you are that there is no medium. This is what all the experimental data suggests. If you have a way to show otherwise, please feel free to explain the method. That fact that we are not able to detect it yet shouldn't allow us to be absolute about it's non existence. But we should assume that it does exist? Sorry, but that is not how science works. In quantum physics, "empty space" is far from being truly empty. Your point being? $\endgroup$– joseph hCommented Dec 30, 2023 at 7:01
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The EM field fills all of space. Its quantum excitations are photons that travel through it with c, the speed of light.
Constant velocities relative to the field are undetectable both in principle and in practice.
answered Jul 19, 2021 at 6:34
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$\begingroup$ The EM field surrounding the Earth is sufficient to move my compass needle. Surely it would be possible for me to fly past the Earth, measuring the change in direction of my compass needle, to calculate my speed relative to the EM field. $\endgroup$ Commented Sep 17, 2022 at 18:39
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$\begingroup$ but that would not let you determine whether it was really you, or the earth, that was doing the moving... which is the point here. $\endgroup$ Commented Sep 17, 2022 at 20:10