studiot Posted June 22, 2023 Posted June 22, 2023 For those who might be interested there is an interesting paper free here. (PDF) An indirect measurement of the speed of light in a General Physics Laboratory (researchgate.net) The indirect method this this paper discusses involves separate measurements of permeability and permittivity and the calculation of c from them both by themselves and some other workers.
exchemist Posted June 22, 2023 Posted June 22, 2023 (edited) 45 minutes ago, Logicandreason said: In Maxwell's equations, which use Mu and Epsilon, there is no such thing as "length contraction". SR will not exist if Mu and Epsilon are reference frame dependant. If SR doesn't exist, then you cant apply Lorentz transformations to the length of anything. You can apply Lorentz to waves frequency, but not to solid objects length. The Lorentz transformation doesn't change the length of objects, only the rate at which a length passes a point. Even thought Lorentz in a desperate attempt to keep his belief in an Aether, suggested that the M&M interferometer has shrunk one arm. But this could only be justified IF there really was an Aether. So your argument involving length contraction is invalid. I don't intend to engage you about the voodoo of Particle physics. It not in Maxwell's equation to calculate the speed of light. Particle Physics and the Standard Model has enough of its own issues without me adding my concerns. Anyway, nothing about Particle Accelerators are in different frames. The whole machine is in the one frame. You can't just airily dismiss particle physics as "voodoo". The determination of all these constants relies on it. You see, in physics, all these things fit together. Maxwell's equations are a c.19th theory that has been explained in the c.20th by virtue of the twin discoveries of relativity and quantum theory. To give you a simple example of this interlinking, Einstein's famous mass-energy equivalence relation E=mc² is a special case of his more general relation E² = (mc²)² + (pc)², in which p is momentum. If p=0, i.e. a system at rest relative to the observer, this reduces to E=mc², which we can observe for instance in the mass and energy balance of nuclear reactions. But for light, consisting of photons with zero rest mass, that term is zero and we are left instead with E=pc. If you apply de Broglie's relation, p=h/λ (from quantum mechanics) to that (λ being the wavelength), and note the relation between speed, wavelength and frequency,ν, for any wave, c=νλ, you get E= hc/(c/ν), i.e. E=hν, which is Planck's relation for the way the energy of a photon depends on its frequency. So that is more evidence that SR, which is where Einstein's formula comes from, is correct and that the invariance of c, which is what SR is all founded upon, is also sound. So it is all interlinked, each piece supports the rest and all the elements have been tested by observation. Your final comment about particle accelerators shows you still don't get it. Sure, the equipment is stationary in the lab (relative to the observers) but the particles whizzing along inside are moving, relative to that frame, at close to the speed of light. So what they experience, from their frame of reference, is a lab - with its coils carrying a current of moving charges and thus a magnetic field, whizzing past them at close to light speed. This in fact is one way to observe the time dilation predicted by SR. Particles that are unstable and have a known decay lifetime, as measured at rest, are found to have longer lifetimes when whizzing along very fast in this way. And the degree to which this happens is as SR predicts. SR wins again! Edited June 22, 2023 by exchemist
swansont Posted June 22, 2023 Posted June 22, 2023 7 hours ago, Logicandreason said: All I'm saying is that from Maxwell's equations and Mu and Epsilon, you can not conclude that Light speed is a universal constant. Because Mu and Epsilon are not universal constants. If you combine and rewrite the equations in the form of a wave equation, you find the relation between these terms and the speed, and that leads to the conclusion that c is invariant. Because light waves are still light waves even if there is motion of the source p\or detector (e.g. your radio works even when your car is moving), and that would not be the case if the speed of the waves varied. 1 hour ago, Logicandreason said: Swansont said: "Something that’s the same everywhere (and over time) in one frame is a constant". And I fully agree, but that's not what Einstein is talking about when he says that c is "constant". Einstein says that light is both constant in the way Swansont had defined, BUT light is ALSO "constant", that is, it is possessing the exact same measured values are measured BETWEEN reference frames that have different velocities. Yes. And in modern terminology, that is called invariance. In 1905 (and in German) the phrasing was somewhat different.
Eise Posted June 22, 2023 Posted June 22, 2023 2 hours ago, Logicandreason said: Anyway, nothing about Particle Accelerators are in different frames. The whole machine is in the one frame. Yes, but the particles are not. Let's take muons as example (again). Normally they have a half life of about 2 μs. In an particle accelerator they live much longer. That's time dilation. In its own reference frame the muon of course stands still. So its half life is still 2 μs. Now imagine the muon can travel 100 rounds in the accelerator before decaying. So from the reference frame of the muon, it also makes 100 rounds. Now how can this be explained in the reference frame of such a muon? 1
Mordred Posted June 22, 2023 Posted June 22, 2023 (edited) 2 hours ago, studiot said: For those who might be interested there is an interesting paper free here. (PDF) An indirect measurement of the speed of light in a General Physics Laboratory (researchgate.net) The indirect method this this paper discusses involves separate measurements of permeability and permittivity and the calculation of c from them both by themselves and some other workers. Thanks Studiot I like the variation of one of the more common tests for the permittivity and permeability relations. It's handy that the equipment is readily accessible to an average student. Edited June 22, 2023 by Mordred
exchemist Posted June 22, 2023 Posted June 22, 2023 (edited) 1 hour ago, Eise said: Yes, but the particles are not. Let's take muons as example (again). Normally they have a half life of about 2 μs. In an particle accelerator they live much longer. That's time dilation. In its own reference frame the muon of course stands still. So its half life is still 2 μs. Now imagine the muon can travel 100 rounds in the accelerator before decaying. So from the reference frame of the muon, it also makes 100 rounds. Now how can this be explained in the reference frame of such a muon? Yes I started on this but changed my mind, thinking it made things too much in one go. But indeed, let's see what he has to say. My guess is he'll divert away onto something that dodges actual experimentation. But I'll be happy to be proved wrong. Edited June 22, 2023 by exchemist
MigL Posted June 22, 2023 Posted June 22, 2023 8 hours ago, Logicandreason said: I just realized you made another logical error. I was the one who said that Mu and Epsilon CHANGED, You claim they do not, I made no such claim. I merely asked you to consider other mechanisms that might keep c invariant. You are the only one here making claims, and not supporting them. Again.
Mordred Posted June 22, 2023 Posted June 22, 2023 2 hours ago, exchemist said: actual experimentation. I can't recall which recent thread in speculation I had posted this. However for precision tests on Lorentz invariance which includes constancy of c. The highest precision test I'm aware of is \(0.707×10^{-11}\) for the upper bound on any deviation for Lorentz invariance. This value is an overall tally of numerous related test methods 1
swansont Posted June 22, 2023 Posted June 22, 2023 Something that science neophytes often miss is that you can do “indirect” confirmations of scientific principles. In this case, you don’t have to measure the speed of light in different frames, since the invariance of c has implications. In the case Mordred has highlighted, it’s Lorentz invariance. Experimentalists can be quite clever in devising experiments where you can do a precision measurement, where you have this situation. e.g. you don’t have to directly measure the fine structure constant to place (rather stringent) limits on its variation in time.
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 9 hours ago, studiot said: For those who might be interested there is an interesting paper free here. (PDF) An indirect measurement of the speed of light in a General Physics Laboratory (researchgate.net) The indirect method this this paper discusses involves separate measurements of permeability and permittivity and the calculation of c from them both by themselves and some other workers. Indirect means you calculated from other results that you ASSUME are related. But even if your assumptions are correct, this is still all done in one frame, so its frame dependent. 9 hours ago, exchemist said: You can't just airily dismiss particle physics as "voodoo". The determination of all these constants relies on it. You see, in physics, all these things fit together. Maxwell's equations are a c.19th theory that has been explained in the c.20th by virtue of the twin discoveries of relativity and quantum theory. To give you a simple example of this interlinking, Einstein's famous mass-energy equivalence relation E=mc² is a special case of his more general relation E² = (mc²)² + (pc)², in which p is momentum. If p=0, i.e. a system at rest relative to the observer, this reduces to E=mc², which we can observe for instance in the mass and energy balance of nuclear reactions. But for light, consisting of photons with zero rest mass, that term is zero and we are left instead with E=pc. If you apply de Broglie's relation, p=h/λ (from quantum mechanics) to that (λ being the wavelength), and note the relation between speed, wavelength and frequency,ν, for any wave, c=νλ, you get E= hc/(c/ν), i.e. E=hν, which is Planck's relation for the way the energy of a photon depends on its frequency. So that is more evidence that SR, which is where Einstein's formula comes from, is correct and that the invariance of c, which is what SR is all founded upon, is also sound. So it is all interlinked, each piece supports the rest and all the elements have been tested by observation. Your final comment about particle accelerators shows you still don't get it. Sure, the equipment is stationary in the lab (relative to the observers) but the particles whizzing along inside are moving, relative to that frame, at close to the speed of light. So what they experience, from their frame of reference, is a lab - with its coils carrying a current of moving charges and thus a magnetic field, whizzing past them at close to light speed. This in fact is one way to observe the time dilation predicted by SR. Particles that are unstable and have a known decay lifetime, as measured at rest, are found to have longer lifetimes when whizzing along very fast in this way. And the degree to which this happens is as SR predicts. SR wins again! I don't agree with your assessment. But its not important. Maxwell's equations are claimed to reveal light speed from just mu and epsilon. There is nothing else to consider here. Epsilon is dependent on the value of Mu, and both these even if measured in real experiments, are necessarily frame dependent values according got he rules of Newtons physics which was the ONLY physics in Maxwell's day. No matter which way you try to twist things, mu and epsilon can only be frame dependent values. As far as those whizzing particles are concerned, they ARE in the same frame as the Lab. The measurement of the particles is reference to the Lab, You do not have any clue what those apparently sentient particles might be experiencing from their subjective point of view. EVERYTHING you are doing in that Lab is Labe referenced. No one has ever isolated a sub atomic particle and measured its life when it is "at rest". No one has isolated a single electron and studied its properties. Same with an imaginary Photon. 9 hours ago, swansont said: If you combine and rewrite the equations in the form of a wave equation, you find the relation between these terms and the speed, and that leads to the conclusion that c is invariant. Because light waves are still light waves even if there is motion of the source p\or detector (e.g. your radio works even when your car is moving), and that would not be the case if the speed of the waves varied. Yes. And in modern terminology, that is called invariance. In 1905 (and in German) the phrasing was somewhat different. Combine whatever you wish, but its all still frame dependent measures. You said, "light waves are still light waves even if there is motion of the source p\or detector" well duh, we all agree on that. That is a statement about the fact that Light waves move inertially. The motion is unchanging. But that is not the same as taking a measurement from differently moving locations, which must all get different results. Interesting that you say one thing but believe another. Because we use the fact that measurements of EM waves speed gives DIFFERENT results if measured from differently moving locations. The evidence to prove my case is Police radar speed detectors. 7 hours ago, Eise said: Yes, but the particles are not. BS. total BS. the observer who is observing a moving train considers that the train is moving in his frame, if it were not, then he cant take a measurement of it. This is really basic Physics here guys.
swansont Posted June 22, 2023 Posted June 22, 2023 27 minutes ago, Logicandreason said: Combine whatever you wish, but its all still frame dependent measures. You said, "light waves are still light waves even if there is motion of the source p\or detector" well duh, we all agree on that. We agree on that now, but prior to 1905 or thereabouts, the ramifications of this were not known. 27 minutes ago, Logicandreason said: That is a statement about the fact that Light waves move inertially. The motion is unchanging. But that is not the same as taking a measurement from differently moving locations, which must all get different results. Interesting that you say one thing but believe another. Because we use the fact that measurements of EM waves speed gives DIFFERENT results if measured from differently moving locations. No, this is not the case. Can you cite any experiment that shows a variable speed of light in inertial frames? 27 minutes ago, Logicandreason said: The evidence to prove my case is Police radar speed detectors. Police radar uses the doppler effect - the change in the frequency of the signal. Not the speed. https://copradar.com/chapts/chapt3/ch3d1.html
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 7 hours ago, Eise said: Yes, but the particles are not. Let's take muons as example (again). Normally they have a half life of about 2 μs. In an particle accelerator they live much longer. That's time dilation. In its own reference frame the muon of course stands still. So its half life is still 2 μs. Now imagine the muon can travel 100 rounds in the accelerator before decaying. So from the reference frame of the muon, it also makes 100 rounds. Now how can this be explained in the reference frame of such a muon? How much energy did you say that large hadron collider consumes? Incredibly strong energy fields all over the place. You cant possibly imagine that this may just possibly have some influence on all particles within that contraption?
swansont Posted June 22, 2023 Posted June 22, 2023 1 minute ago, Logicandreason said: How much energy did you say that large hadron collider consumes? Incredibly strong energy fields all over the place. You cant possibly imagine that this may just possibly have some influence on all particles within that contraption? But we also see this with the muons, as Eise has explained, without a “contraption”
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 6 hours ago, MigL said: I made no such claim. I merely asked you to consider other mechanisms that might keep c invariant. You are the only one here making claims, and not supporting them. Again. I see your angle. Ok. Yes, mu and epsilon both are frame dependent as is Energy measurement. But Mass, along with length is unaffected by relative motion, and is not frame dependent. 2 hours ago, swansont said: Something that science neophytes often miss is that you can do “indirect” confirmations of scientific principles. In this case, you don’t have to measure the speed of light in different frames, since the invariance of c has implications. In the case Mordred has highlighted, it’s Lorentz invariance. Experimentalists can be quite clever in devising experiments where you can do a precision measurement, where you have this situation. e.g. you don’t have to directly measure the fine structure constant to place (rather stringent) limits on its variation in time. You cant prove " invariance of c". The claim is irrational. In fact the opposite is true. Only the constancy of motion is invariant, but the subjective measure of speed is obviously and necessarily frame dependent.
swansont Posted June 22, 2023 Posted June 22, 2023 3 minutes ago, Logicandreason said: But Mass, along with length is unaffected by relative motion, and is not frame dependent. Length and time are most definitely frame-dependent. 4 minutes ago, Logicandreason said: You cant prove " invariance of c". The claim is irrational. Not understanding is not the same as being irrational 4 minutes ago, Logicandreason said: In fact the opposite is true. Only the constancy of motion is invariant, but the subjective measure of speed is obviously and necessarily frame dependent. And yet experimental physics shows this not to be the case. Who’s right? That’s a real puzzler.
Mordred Posted June 22, 2023 Posted June 22, 2023 (edited) I think the difficulty you might be having is that All measurements are frame dependent. However the difference is with invariant quantities regardless of the chosen frame or multiple frames every observer will measure the same value. Variant quantities will vary between different observers. It is the latter we often term frame dependent. Edited June 22, 2023 by Mordred
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 17 minutes ago, swansont said: We agree on that now, but prior to 1905 or thereabouts, the ramifications of this were not known. No, this is not the case. Can you cite any experiment that shows a variable speed of light in inertial frames? Police radar uses the doppler effect - the change in the frequency of the signal. Not the speed. https://copradar.com/chapts/chapt3/ch3d1.html The ramifications are that measurement of light speed is frame dependent. Its not possible to devise any such experiment as you describe. Changes in the perceived frequency is caused by changes in relative speed. The wave length and frequency of the signal never changes, only the approach speed of the person taking the measurements. Because measurements of ANYTHING can only be FRAME DEPENDENT. No other option exists. 6 minutes ago, swansont said: Length and time are most definitely frame-dependent. Only if you have already proved that SR is correct, and you haven't done that. 6 minutes ago, swansont said: Not understanding is not the same as being irrational I'm sorry that you fail to understand simple Physics, and prefer to ponder fantastical pseudo science instead. 7 minutes ago, swansont said: And yet experimental physics shows this not to be the case. No experiment has ever tested light speed of 300 million meters per second is the same in other frames. 7 minutes ago, Mordred said: I think the difficulty you might be having is that All measurements are frame dependent. However the difference is with invariant quantities regardless of the chosen frame or multiple frames every observer will measure the same value. Variant quantities will vary between different observers. The idea of "invariant measurements" is nonsensical and opposite to Physics principals and rational thought. The observations of "invariant MOTION states " is logical and in keeping with those rules of Physics. The "difficulty" you are clearly having which prevents you from clear thinking, is because you can't separate the concept of "constant motion", from the "subjective measurements of motion". you think they are the same. The first is universal, the latter is necessarily reference frame dependent. -1
swansont Posted June 22, 2023 Posted June 22, 2023 1 hour ago, Logicandreason said: The ramifications are that measurement of light speed is frame dependent. Its not possible to devise any such experiment as you describe. No? You can’t measure the speed of light in different frames of reference? Say, doing itat noon, and then 12 hours later, where the earth’s rotation has your lab moving in the opposite direction? And doing this at 6 month intervals, so the earth’s orbit is in the opposite direction? Surely something so basic has been done. Even if not systematically, it can’t be the case that all of the measurements of the speed of light have happened at the same time on the same day of the year. This would show up in the data, if it were true. 1 hour ago, Logicandreason said: Changes in the perceived frequency is caused by changes in relative speed. The wave length and frequency of the signal never changes, only the approach speed of the person taking the measurements. Because measurements of ANYTHING can only be FRAME DEPENDENT. No other option exists. You just asserted that mass and length are not frame dependent. You’re right about rest mass, but the mere assertion is contradicted by this claim. The least you can do is be consistent. 1 hour ago, Logicandreason said: Only if you have already proved that SR is correct, and you haven't done that. c being invariant is proven by electrodynamics, as I have described. SR is shown to be correct by various experiments, perhaps most famously by the Hafele-Keating experiment 1 hour ago, Logicandreason said: I'm sorry that you fail to understand simple Physics, and prefer to ponder fantastical pseudo science instead. You don’t get to judge others’ understanding of physics. 1 hour ago, Logicandreason said: No experiment has ever tested light speed of 300 million meters per second is the same in other frames. They have, as I have described above. 1 hour ago, Logicandreason said: The idea of "invariant measurements" is nonsensical and opposite to Physics principals and rational thought. The concepts of physics are completely independent of your understanding of them 1 hour ago, Logicandreason said: The observations of "invariant MOTION states " is logical and in keeping with those rules of Physics. The "difficulty" you are clearly having which prevents you from clear thinking, is because you can't separate the concept of "constant motion", from the "subjective measurements of motion". you think they are the same. The first is universal, the latter is necessarily reference frame dependent. Yeah, whatever.
Mordred Posted June 22, 2023 Posted June 22, 2023 1 hour ago, Logicandreason said: The ramifications are that measurement of light speed is frame dependent. So you keep claiming over and over again. Your claims do not change 100 years of experimental research and precision tests. This has been pointed out to you numerous times. However you keep ignoring or denying it. Guess what your opinion won't change the evidence. 1 hour ago, Logicandreason said: The idea of "invariant measurements" is nonsensical and opposite to Physics principals BS pure and simple 1 hour ago, Logicandreason said: in keeping with those rules of Physics. The You obviously don't understand physics well enough to determine anything regarding the rules of physics.
John Cuthber Posted June 22, 2023 Posted June 22, 2023 1 hour ago, Logicandreason said: The ramifications are that measurement of light speed is frame dependent. How come nobody but you has noticed?
Mordred Posted June 22, 2023 Posted June 22, 2023 I have to ask this. Did you even bother looking at the link provided by Studiot ? There is a very important detail you missed with regards to \(\mu_O\). I won't tell you what it is, not yet anyways. I want to see if you can find that important detail yourself.
MigL Posted June 22, 2023 Posted June 22, 2023 1 hour ago, Logicandreason said: But Mass, along with length is unaffected by relative motion, and is not frame dependent. It is called rest mass for a reason; the rest frame is the only frame where its value is valid. In all other frames mass would be measured different, because what we call mass, the resistance to changes in inertia, increases dramatically as relative motion approaches c . That is the main reason protons at the LHC can slam into targets with energies in the TeV range. I believe Swansont has already addressed your mistaken beliefs concerning the supposed 'invariance' of length ... So you've got no mathematical proof, nor any observational evidence. You know what that leaves ? Squat !
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 1 hour ago, swansont said: where the earth’s rotation has your lab moving in the opposite direction? Opposite to what? 1 hour ago, swansont said: You just asserted that mass and length are not frame dependent. You’re right about rest mass, but the mere assertion is contradicted by this claim. The least you can do is be consistent. The length of an object is relative to the object itself, so never changes, nor does Mass. There is no such thing as "rest mass". So I am consistent. 1 hour ago, swansont said: c being invariant is proven by electrodynamics, as I have described. Not if Mu and Epsilon are relative to the frame. 1 hour ago, swansont said: SR is shown to be correct by various experiments, perhaps most famously by the Hafele-Keating experiment No, the results and conclusions have been disputed, no experiment is conclusive. 1 hour ago, swansont said: The concepts of physics are completely independent of your understanding of them I can say the same to you. 1 hour ago, swansont said: Yeah, whatever. And that is a pathetic failure to admit that fact that "constancy of motion" is not the same as a "measurement of that motion". Do you deny that this is true? -1
Mordred Posted June 22, 2023 Posted June 22, 2023 With that last response to Swansont you have proven to me at least. We are not accomplishing anything here.
Logicandreason Posted June 22, 2023 Author Posted June 22, 2023 2 minutes ago, MigL said: It is called rest mass for a reason; the rest frame is the only frame where its value is valid. In all other frames mass would be measured different, because what we call mass, the resistance to changes in inertia, increases dramatically as relative motion approaches c . That is the main reason protons at the LHC can slam into targets with energies in the TeV range. I believe Swansont has already addressed your mistaken beliefs concerning the supposed 'invariance' of length ... So you've got no mathematical proof, nor any observational evidence. You know what that leaves ? Squat ! But there is no such thing as "rest mass". there is only Mass. Look it up. What possibly aspect about moving, is going to add more Mass to a brick? Did you add more brick matter to the brick? Where do that come from? I thought you said the brick has shrunk in length? So how come there is now mare Mass? "Swansont has already addressed your mistaken beliefs concerning the supposed 'invariance' of length" No, he only repeated the same standard statements, that I've just shown are nonsense. A bricks length is relative to each end of the brick, and has nothing to do with any external frame. This is basic Newtonian Physics, which you said was still valid. We measure length of a brick for one end to the other. that length is invariant. 4 minutes ago, Mordred said: With that last response to Swansont you have proven to me at least. We are not accomplishing anything here. If you are going to say "opposite to something", you need to state to what are you referring? Opposite to the light wave? we get doppler shift. Opposite to the source of the light? that's not a valid factor as we all have agreed.
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