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Tags electrodynamics , magnetic force , pseudoforces , relativity , strong force

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Old 23rd July 2012, 11:15 AM   #41
quarky
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Originally Posted by OnlyTellsTruths View Post
A semi-odd tangent in this thread.

I've seen that "documentary" [url=http://www.imdb.com/title/tt0109508/]Crumb (1944)[/b] at least twice. A very interesting man, movie, (and family)... to say the least.
It was added as fiber. The meal here is fairly dense. Its well out of my comfy frames of reference, but I find it pretty interesting, and its usually rewarding to see what Sol has to say. Of all the smart people here, he's predictably not a jerk.
Shouldn't fluff his ego, though I suspect he's fairly immune to that stuff.

My twin merry-go-rounds/moving still frames version of observation is, admittedly, fairly juvenile.

Just didn't want the thread to die.
Sometimes, during the awkward silence, you only need to ask "So, who do you think will win the world series this year?"
Suddenly, the dialog is back; with luck, i get off with a warning; and its chalked up to chemistry and catalysts, which somehow tie back into the better analogy.
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Old 23rd July 2012, 04:36 PM   #42
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Originally Posted by PixyMisa View Post
What if there was a merry-go-round without inertial forces?

It would instantly accelerate to infinite velocity and thus have infinite relativistic mass, causing the merry-go-round, the children, their ball, and the planet Earth to collapse into a black hole, which would rather put a damper on things.
Not if it were powered by an AC induction motor. The maximum speed of the merry-go-round would be a fixed ratio of the supply frequency. If it spun any faster than that, the motor would start acting like a generator and (instantly) slow the merry-go-round down.
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Old 23rd July 2012, 05:13 PM   #43
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Originally Posted by Eggs Ackley View Post
Do you understand that I'm trying to say that the Thomas precession creates reference frames....
Do you understand that Thomas precession does not create reference frames?
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Old 23rd July 2012, 11:47 PM   #44
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Originally Posted by OnlyTellsTruths View Post
A semi-odd tangent in this thread.

I've seen that "documentary" [url=http://www.imdb.com/title/tt0109508/]Crumb (1944)[/b] at least twice. A very interesting man, movie, (and family)... to say the least.
Wow, I could not have possibly messed up that link any worse (Crumb would have liked it though).

Fixed link:

Crumb (1994)
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Old 25th July 2012, 06:38 PM   #45
Eggs Ackley
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Originally Posted by Reality Check View Post
Do you understand that Thomas precession does not create reference frames?
That was not a good choice of words on my part. I agree the T.P. does not create reference frames. But I think it is something that happens to reference frames, and not just to the spin. I take it from your choice of link that you mean to imply it is an effect limited to the spin only.

I had noticed that that wikipedia article is rather tepid, saying only the T.P. is an "effect on the spin". This is a rather limited view, I think. A more general interpretation is at least common. (Muller has even argued (in an AMJ paper I can give you the reference of, but it's not posted free on line) the T.P. is a torque. (Malykin seemingly ridicules him for this in his review article, also not available free online.)) Most authors (and including Jackson) say the T.P. is a kinematical effect, and at the least imply that it's a relative feature between certain reference frames. It is, after all, a simple consequence of the algebra of the Lorentz transformation, which according to an Einsteinian worldview is telling us something about the structure of reality, if there is no preferred inertial frame.

Seems to me this point of view that the T.P. is only an effect on the spin is a retreat to the Lorentzian interpretation of relativity. This was the position of the sophisticated anti-Einsteinian Petr Beckmann. Other smart anti-relativists like T. E. Phipps Jr. (whose father first measured the magnetic moment of atomic hydrogen) argue that the necessary existence of a Thomas precession as a consequence of Einsteinism implies that relativity can't be true. (Phipps said, "Whence cometh the energy of the Thomas precession?") I think the point of view that it is the whole reference frame (albeit not an inertial frame) that undergoes the Thomas precession is the only Einsteinian interpretation, and it seems completely natural to me.

Malykin (the reference is in my e-print) says this (in translation, anyhow):

Quote:
The Thomas precession (TP) is a relativistic kinematic
effect, which consists in that the spin of an elementary particle
or the rotation axis of a macroscopic mechanical gyroscope,
as well as a coordinate axis of a reference frame, moves along
a curvilinear trajectory rotating (precessing) about the axes of
a laboratory inertial reference frame (IRF). The Thomas
precession relates the angular rotation velocity of the spin of
an elementary particle following a curvilinear orbit (for
instance, a circumference) to the angular velocity of the
orbital motion. The Thomas precession does not occur due
to the action of some forces responsible for variations in the
angular position of a body, and therefore has a purely
kinematic origin.

This statement implies at least that the effect of the T.P. is not limited to just the spin.

This is how I reference the course materials I mentioned previously, that are now taken down:

2. R. G. Littlejohn, University of California, Berkeley,
Physics 209, Fall 2002, Notes 5: Thomas Precession. See
the statement on page 8, “... if we fix ourselves to the parallel
transported frame, we will feel no centrifugal forces.”

Note the quoted part, which I promise was copied directly. (I now wish I had downloaded the whole section when I had the chance, as it was from a very sophisticated point of view and did describe a certain arbitrariness of it, that I think he compared or linked to the arbitrariness of a gauge transformation. When I get the chance I think I will see if it's on the wayback machine.)

This is another thing that can be argued about 'till the cows come home, I suppose, and I don't claim to be an authority on it or even particularly knowledgable or sophisticated about it. Still, I think I'm entitled to an opinion and point of view, and that my point of view about what the T.P. is is not an entirely crackpot point of view, and I have an analysis with more to come that I believe supports a claim that under such an interpretation of the T.P., the existence and nature of the magnetic force is implied, as well as other forces one of which could play the role of the strong force. I suspect the other part might correspond to the weak force but I haven't done any detailed comparison between the weak and (anti-Euler) force. They are both pretty complicated though and the anti-Euler force like the weak force would operate at nuclear scales.

So then, if you were to accept provisionally that the T.P. is a kinematical effect that leads to a rotation of certain reference frames relative certain inertial frames such that Coriolis and centrifugal forces are not experienced in the Thomas-precessing frame, would it not follow kinematically that an observer in the inertial frame would measure real forces apparently acting?

Last edited by Eggs Ackley; 25th July 2012 at 06:50 PM.
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Old 26th July 2012, 05:16 PM   #46
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Originally Posted by Eggs Ackley View Post
That was not a good choice of words on my part. I agree the T.P. does not create reference frames. But I think it is something that happens to reference frames, and not just to the spin.
...wall of text snipped...
Still not a good choice of words. Nothing happens to reference frames. Thomas precession does not change them. Observers select them and they stay the same unless an observer chooses to change their frame of reference.
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Old 14th April 2013, 11:09 AM   #47
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There is something I was missing about how the Thomas precession works. That is, it is in the eye of the beholder. Perhaps this is what RC you are trying to get at.

For example, if someone wanted to construct the magic merry-go-round, they would only need a can of paint or some chalk to draw a circle on the playground, and a rocketship to get in and do an acceleraing flyby. Then, the rocket-based observer would see the children in the circle rotating, but of course the laws they operate by know nothing of this rotation. The rocket-based observer however using the established laws of relativity calculates that there must be forces countering his expectation that thrown balls should follow trajectories that curve in the children's rest frame on account of the Thomas rotation that is real to him.

This idea, I realized last fall, can fix the two main problems with my conjecture that the magnetic force is a kind of Coriolis force (an anti-Coriolis force, to be specific) that manifests due to the Thomas precession. The first problem is that my original formulation required an acceleration of the field-source charge to cause a magnetic field, but according to Maxwell's equations, no such charge acceleration is needed. A steady current in a straight wire will create a magnetic field. This problem is solved in my new model because the acceleration is of the (test) charge feeling the effect of the magnetic field rather than that creating it. It's not very hard to show with relativistic kinematics that a just-suitable acceleration of the test charge must always be present when there's a magnetic force acting.

The second big problem was that when I calculated the magnetic force law according to my old model, there was a mass-ratio term that isn't present in the known magnetic force. The mass-ratio term simply reflected (in part) that the Coriolis like any "inertial" (or pseudo) force depends on the mass of the object it appears to be acting on. The denominator part of the mass ratio term, which isn't present for an ordinary Coriolis force, comes from the acceleration (as in a=F/m) that causes the Thomas precession. So, in the model where the field-source charge acceleration is causing the field, the mass ratio term is between two different particles and so is noticable if the charges have different masses. The new model where the magnetic force is due to acceleration of the test charge fixes this problem nicely since then the mass ratio is of the test particle to itself and so is always unity.

I figured that much out last fall and have been trying ever since to get it pulled together into an exact relativistic kinematic description suitable for submitting to a physics journal. It's proving rather difficult. I expect when it's done it will seem obvious and simple in retrospect, but so far it's been surprisingly elusive. I'm able to show that an accelerated observer sees pseudoforces as real but getting these to persist for non-accelerated observers is the critical bit. I made an update of my arxiv paper in January that attempts at least to correct the misconception of the earlier versions, and outlines the approach I've been pursuing.

A couple of weeks ago, though, I had a new thought that is probably going to change my whole direction of research. That is that the other pseudoforces of rotation, i.e. the centrifugal and Euler forces, actually need to be present already in electrodynamics if my whole line of reasoning has any merit. This is expected as a consequence of the relavistic nature (covariance) of electrodynamics. As I have tried to explain in this thread starting with the OP, in particular an anti-centrifugal force if it is real will resemble the strong force in that it will always be attractive, even between charges of similar polarity. So then, when I looked for an anti-centrifugal-like force in relativistic electrodynamics, I found something that could be it almost immediately. It turns out, quite surprisingly to me and perhaps everyone else, there is a force in electrodynamics between two charges that appears to become attractive in the highly relativistic limit, independent of the relative polarity of the charges. Also, it has an inverse third-power of separation (r) dependence, and so can seemingly overcome Coulomb repulsion at very short range, which is of course a 1/r^2 force.

There are a lot of pesky Lorentz (gamma) factors involved though (that are tending to infinity) and retardation effects that may yet rule it out, however. I think I have to work more of this out before I can submit it to a journal. There is aso a classic paper by Schild, "Electromagnetic two-body problem", that as I interpret it directly contradicts that the strong force can already be in Maxwell-Lorentz electrodynamics (or Wheeler-Feynman ED either). Still I think it's amazing and worth further consideration, that there can be an always-attractve and strong at close range force apparently already present in electrodynamics.
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Old 15th April 2013, 12:58 PM   #48
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Originally Posted by Eggs Ackley View Post
There is something I was missing about how the Thomas precession works. That is, it is in the eye of the beholder. Perhaps this is what RC you are trying to get at.
...basic physics about the magic roundabout snipped...
...more wall of text snipped...
That is exactly whatI was getting at: Thomas precession is physics. All physics needs a reference frame.

The magnetic force is not related to any kind of Coriolis effect except trivially, e.g. they both involve cross products.
It does not manifest due to Thomas precession.
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Old 20th April 2013, 12:40 PM   #49
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Originally Posted by Reality Check View Post
The magnetic force is not related to any kind of Coriolis effect except trivially, e.g. they both involve cross products.
It does not manifest due to Thomas precession.

The correspondence is certainly much stronger than that. Apart from that the magnetic force involves the velocity crossed onto the magnetic field (which is formally similar to a Coriolis force if the magnetic field is replaced by the angular velocity of the coordinate system rotation), it also has the proper magnitude when the acceleration causing the Thomas precession is due to a Coulomb field.

I'm not the only one claiming this. It's in the peer-reviewed literature. See Bergstrom: http://link.springer.com/article/10.1007%2FBF02895716#

What I am saying I think goes beyond what Bergstrom said, though. I claim that the magnetic force can be viewed as a kinematical consequence of a lack of Coriolis effect accompanying Thomas precession. If we have the same physics described in two coordinate systems, one of which is rotating relative to the other, then there simply must be a Coriolis effect in one relative to the other. And since an accelerating observer can see Thomas precession of an inertial frame, it's clear that peudoforces of rotation are not present in Thomas-precessing reference frames. There's a tangible effect present in the accelerated observer's description, that persists when the description is Lorentz-transformed from the accelerated observer's frame to an inertial frame.

It's best seen when we abstract away the magnetic force and simply consider two charged particles interacting electromagnetically. I could explain this in detaill but I don't want to present you with a "wall of text". Suffice it to say, the magnetic part of the interaction is then described by a vector triple product, that can be identified with a velocity crossed onto the angular velocity of the Thomas precession seen from the point of view of the particle being acted on by the magnetic force. It is correct in both form and magnitude. (The 1/2 in the T.P. formula cancels the 2 in the Coriolis force, as needed to agree with the magnetic interaction that has neither a 2 nor a half. And, the particular magnitude of the T.P. when the acceleration causing the T.P. is due to Coulomb attraction or repulsion gives the correct magnitude for the magnetic interaction.)

It's nice enough to have a new way to understand the magnetic force, but what I think is really interesting is that it predicts oher relativistic-kinematical forces corresponding to the centrifugal and Euler pseudoforces. Since the centrifugal pseudoforce is always repulsive, the anticentrifugal force is always attractive (like the strong force). When I first recognized this, about a year and a half ago and not too long before I started this thread, I thought these forces were not present in Maxwell-Lorentz electrodynamics. A couple of weeks ago though I got to thinking that the Lorentz covariance of ED requires them to be in there, so I decided to look. It turns out that there does seem to be a way that the magnetic force can act just like the anticentrifugal force I expect. I'm still investigating whether it can really overcome Coulomb repulsion as needed to bind like charges. At first glance it seemed to be able to, but on closer examination I think maybe it will just exactly equal and cancel electric repulsion in the relativistic limit, without actually overcoming it. Maybe this can be related to asymptotic freedom.

I'm not keeping the details a secret, if anyone is interested in how the magnetic force between two charges can become attractive regardless of the sign of the charges, I'll be happy to explain further. It's really quite obvious provided you're looking at the relativistic form of the field due to a point charge.
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Old 22nd April 2013, 05:23 PM   #50
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Originally Posted by Eggs Ackley View Post
The correspondence is certainly much stronger than that.
Actually it is not.
Thomas precession is a relativistic correction to the spin of a elementary particle. It provides a relativistic correction to the magnetic field generated from a charged elementary particle. The magnetic field would be there even if Thomas precession did not exist.
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Old 23rd April 2013, 05:34 AM   #51
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Originally Posted by Eggs Ackley View Post
I claim that the magnetic force can be viewed as a kinematical consequence of a lack of Coriolis effect accompanying Thomas precession.
Eggs, mass is not the same thing as charge. Different particles and objects have (very) different mass/charge ratios. Coriolis forces act on mass. Magnetic forces act on charge. Therefore, they cannot possibly be the same, one cannot possibly explain the other, and one cannot possibly cancel the other.

Quote:
If we have the same physics described in two coordinate systems, one of which is rotating relative to the other, then there simply must be a Coriolis effect in one relative to the other. And since an accelerating observer can see Thomas precession of an inertial frame, it's clear that peudoforces of rotation are not present in Thomas-precessing reference frames.
It's not clear at all. In fact, it's obviously wrong.
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Old 23rd April 2013, 05:52 AM   #52
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Originally Posted by Eggs Ackley View Post
I'm talking about the precession of a reference frame fixed to a body that is translating, and accelerating perpendicularly (say) to the direction of translation, relative to another reference frame that is an inertial reference frame. This is the Thomas precession. Surely this is not something you haven't heard of. Here is a wikipedia article:

http://en.wikipedia.org/wiki/Thomas_precession

and there is a good description of particle rest frames in Jackson Classical Electrodynamics chapter 11 or in the Malykin paper I cite in my paper I linked above.

So then, if we have a Thomas-precessing reference frame, attached to a particle or rocketship or nothing at all, we need to be able to write the laws of physics, let's comsider just the laws of electrodynamics, in it. It is an allowed frame of reference, although not an inertial one, so it is not unreasonable to ask what does electrodynamics look like to an observer who is stationary in such a reference frame.

It is a more general question but I'm considering it at the atomic scale or smaller here. I'm not thinking quantum mechanically, however; I'm thinking of a classical Rutherfordian hydrogen atom model (say) with a point-charge electron. We can call the reference frame where the center of mass of the atom is at rest the laboratory frame, then the Thomas-precessing frame is one in which the electron is at rest. However, this frame is obtained from the lab frame by only pure Lorentz boosts. Start in the lab frame and boost to a frame where the electron is momentartily at rest, then continue applying a sequence of infinitesimal boosts as needed to maintain the electron stationary in the sequence of these inertial frames.

After the first infinitesimal boost, if we want to transform back to the laboratory frame we will have to apply a rotation as well as a boost, and time variation of the rotation needed is the angular velocity of the Thomas precession.

Jackson makes the careful distinction that the rest frame defined this way is actually a sequence of inertial frames. In the rest frame sequence as defined this way, the electron is always instantaneously accelerating, but never acquires a nonzero velocity. As Jackson observes, this isn't a convenient frame to write equations of motion in, so it is convenient to define also a non-inertial reference frame where the electron is both stationary and non-accelerating. This frame is determined at each point in time by rotating the inertial rest frame by an amount based on the angular velocity of the Thomas precession and the elapsed time from an arbitrary reference time when we can have performed the initial boost. Strictly, this is the Fermi-Walker frame and is the frame that I am referring to. Other descriptions of it are found in for example Munoz, "Spin–orbit interaction and the Thomas precession: A comment on the lab frame point of view," Am. J. Phys. 69(5), May 2001, and Schild and Schlosser, "Fokker Action Principle for Particles with Charge, Spin, and Magnetic Moment," JMP 6(8), 1965, and many other sources.

If I can simply say that I am talking about Fermi-Walker frames, then what I am proposing is that if I am to write down the equations of electrodynamics is such frames, I should not have to add pseudoforces of rotation (that is, Coriolis, centrifugal, and Euler forces) as I would ordinarily in a frame that is rotating relative to an inertial frame.



I might mention Larmor's theorem and the formal similarity of the magnetic force to a Coriolis force, but I came upon it in passing when I was trying to write the equations of classical motion of two interacting point charges in the Fermi-Walker frame of one of them. I was doing this as a proficiency test of my understanding of the problem of the classical hydrogen atom with an electron with intrinsic spin and intrinsic magnetic moment.

I needed to get descriptions in both the Fermi-Walker and lab frames and confirm they were consistent, because I wanted to be able to build a classical positronium atom model where the electron and positron both have intrinsic spins. Initially though I was neglecting the intrinsic spins and intrinsic magnetic moments, in order to simplify the problem. When I sat down to write the equation of motion of the positron in the Fermi-Walker frame of the electron, I initially did put in explicitly the Coriolis force I expected to be required to describe the motion of the positron. To my surprise this term was exactly the same as the magnetic force term when I wrote the equation of motion in the lab frame.

I felt like I had uncovered something important, but after a day or so I realized that something had to be wrong because a Coriolis force lives only in the rotating frame and has to vanish in the inertial frame. I kept thinking about it however because it seemed extremely unlikely to me that the magnetic force magnitude would equal the expected magnitude of the Coriolis force of the Thomas precession by mere coincidence.

That was over three years ago. I can post a link to where I tried to discuss it on phyorg. It took about a year before it dawned on me that a lack of a Coriolis force in the Thomas-precessing Fermi-Walker frame would have to manifest as an actual force in the inertial lab frame. So then having figured it out, I thought, it would be easy to show how it works. But it took another two years, working off and on, before I could get it to work out.

I am still not sure if I was just interpreting the angular velocity equation in Jackson incorrectly, or whether it is stated incorrectly, but I had a sign error that caused me to end up with a too-strong magnetic force in the inertial frame if I assumed no Coriolis force in the Fermi-Walker frame. I eventually realized I had to change the sign, and right after that I remembered that Malykin had said the same thing (that the sign in Jackson is wrong), and so I used Malykin's form of the angular velocity of the Thomas precession and got that the magnetic force could be equated with an anti-Coriolis force of the Thomas precession, as I think I show in my paper.

(Strictly speaking, what I try to show is that the lab frame equations of motion for the classical electromagnetic two-body problem without spin are equivalent to a force in the Fermi-Walker frame that is strictly radial. I realize that in the nonrelativistic treatment I use that the argument is short of airtight, and that's why I said it's only a plausibilty argument for the magnetic force being the anti-Coriolis force of the Thomas precession. But it is at least a quantitative plausibilty argument. However as I have already mention I have a relativistic version that retains all relatiivistic terms including delay-related ones to order (v/c)^2 that I hope to make public in a month or so. It was actually essentially finished when I did the short version as previously linked, but I was having trouble interpreting it. I was not expecting the additional dynamical restriction beyond the need for equal particle masses. I thought it was just not working out. So I tried the simplified version and realized that there is apparently an additional dynamical restriction that the two particle velocities be equal magnitude and opposite direction. Certainly I was not happy with this restriction but it seems that it is demanded by relativistic covariance if the magnetic part of the Lorentz force is to be as usually accepted. But since such a restriction can't be enforced generally I think the implication is that the magnetic force must be more complex than now recognized. We also need to account for the anticentrifugal and anti-Euler forces that covariance demands.

Well I hope that helps. I can explain a lot further and I am even willing to try your rocketship question but for the time being I am having very little free time to think about it in a new way. However another way to think about it that I have already figured out is how the anticentrifugal force looks to the children on the magic inertialess merry-go-round. They also think there is an attractive force present. They see the people standing in the park as orbiting around them, and can even calculate (if they are exceptionally smart children) what is the force law needed to hold the people in orbit, just as we can calculate the gravitational force law from the orbital motion of the moon.
I'm going to put this in the friendliest, most helpful way I can: when Sol and a few others here cannot tell what you are trying to describe/ask about/theorize then the odds are exceptionally high that you are not explaining yourself at all well or you are describing nonsense. Can't guarantee it as as written here this is above my pay-grade, but I'll tend to stick with it absent new evidence.
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Old 23rd April 2013, 09:05 PM   #53
Eggs Ackley
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Originally Posted by Reality Check View Post
Actually it is not.
Thomas precession is a relativistic correction to the spin of a elementary particle. It provides a relativistic correction to the magnetic field generated from a charged elementary particle. The magnetic field would be there even if Thomas precession did not exist.
It's not an option for the Thomas precession not to exist. As you probably know, it's part of the mathematical structure of the Lorentz group. So, if there were no Thomas precession, the world wouldn't be relativistic, and there wouldn't be any magnetic field at all.

It's true that one need not invoke the Thomas precession to describe the magnetic field, but it's necessary that they coexist. Understanding the nature of the coexistence gives new insight into the nature of non-Coulomb forces.
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Old 23rd April 2013, 10:33 PM   #54
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Question What is the magnetic field caused by Thomas precession of a Foucault pendulum

Originally Posted by Eggs Ackley View Post
It's not an option for the Thomas precession not to exist.
Wrong: Thomas precession is a relativistic correction to the spin of a elementary particle.
No elementary particle involved = no Thomas precession.
Treat an elementary particle classically = no Thomas precession.
Look at a lump of material that is not rotating = no Thomas precession.

Thomas precession is not part of the mathematical structure of the Lorentz group.
It is a consequence of applying the mathematical structure of the Lorentz group to spinning objects, i.e. treating then relativistically. So when we do this to a Foucault pendulum:
Quote:
Thomas precession gives a correction to the precession of a Foucault pendulum. For a Foucault pendulum located in the city of Nijmegen in the Netherlands the correction is:
Eggs Ackley, What is the magnetic field caused by Thomas precession of a Foucault pendulum?
You can assume that the pendulum is made of lead.

Now do the same calculation for a Foucault pendulum that actually is magnetic!

It is obvious that Thomas precession exists.
It is obvious that magnetic fields exist.
There is no requirement the they "coexist" as you assert.
There are trival things like electrons in atoms undergo Thomas precession and that some materials have magnetic fields.

Last edited by Reality Check; 23rd April 2013 at 10:41 PM.
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Old 23rd April 2013, 11:14 PM   #55
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RC, it's the gravitomagnetic field (http://en.wikipedia.org/wiki/Gravitoelectromagnetism) that can be similarly derived as a consequence of the Thomas precession due to gravitational acceleration as the magnetic field can be derived from Thomas precession due to Coulomb acceleration.

Bergstrom covers this in the paper that I linked to. Sorry it's behind a paywall. I can't copy the text from it either because the pdf I have is based on a scan. Anyhow it's fairly self evident and I realized it independently, as now have you.

There is always a Thomas precession associated with a magnetic field provided that the magnetic field is acting on a moving charge, and so causing an acceleration of the charge.

Thomas precession is a consequence of the noncommutativity of succesive non-colinear Lorentz boosts. Sounds like a mathematical property to me.

I had a browser crash that wiped out a rather detailed response I was almost finished writing to Sol. It's late here so I'm not going to rewrite it tonight.

Last edited by Eggs Ackley; 23rd April 2013 at 11:20 PM.
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Old 24th April 2013, 08:02 AM   #56
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Originally Posted by sol invictus View Post
Eggs, mass is not the same thing as charge. Different particles and objects have (very) different mass/charge ratios. Coriolis forces act on mass. Magnetic forces act on charge. Therefore, they cannot possibly be the same, one cannot possibly explain the other, and one cannot possibly cancel the other.


The Thomas precession that an observer moving with a charge being accelerated by a Coulomb force sees is proportional to the acceleration of the charge, which is inversely proportional to the mass of the charged particle. This inverse mass factor cancels the mass factor in the Corioilis force that that observer expects due to the Thomas precession. This is in that Bergstrom paper (behind a paywall), and the one I linked by Royer, or mine (both on arxiv).


Originally Posted by sol invictus View Post
It's not clear at all. In fact, it's obviously wrong.
An accelerating observer with an acceleration component transverse to his velocity relative to an inertial frame will see Thomas precession of the inertial frame. Clearly, there is no Coriolis force in the inertial frame caused by its Thomas precession seen only by the accelerated observer. The accelerating observer however sees a force acting in the inertial frame due to the Thomas precession that can be regarded as the force opposite the Coriolis force he expects in the inertial frame due to its Thomas precession. (It is obtained by making a sequence of Lorentz transformations of the observer position from the inertial frame to the accelerating reference frame of the observer.) I call this an anti-Coriolis force. Some of this force will remain if the accelerated observer uses a sequence of Lorentz transformations to calculate the expected motion of an accelerating test particle he's co-moving with in a second inertial frame that is uniformly translating relative to the first inertial frame. If the first inertial frame is the rest frame of an arbitrarily heavy charge (so as not to be accelerated by the test charge) and the second is a laboratory frame where the heavy charge is uniformly translating, the residual anti-Coriolis force seen acting on the charged test particle by the accelerating observer is what we call the magnetic force.
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Old 24th April 2013, 08:17 AM   #57
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Originally Posted by sol invictus View Post
It's not clear at all. In fact, it's obviously wrong.

Here is another take on the existence rotational pseudoforces due to Thomas precession, from Robert G. Littlejohn's course material linked in the wikipedia article linked by RC:

http://bohr.physics.berkeley.edu/cla...s/thomprec.pdf

Near the bottom of page 11:


"If we do this with the parallel transported frame, we find in general that the parallel transported frame after a period of the motion is related to the original frame by some rotation. This is in spite of the fact that the parallel transported frame is rotationless," without centrifugal forces."
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Old 25th April 2013, 04:20 PM   #58
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Question Cte your sources for this magnetic field = Thomas precession + Coulomb acceleration

Originally Posted by Eggs Ackley View Post
RC, it's the gravitomagnetic field (http://en.wikipedia.org/wiki/Gravitoelectromagnetism) that can be similarly derived as a consequence of the Thomas precession due to gravitational acceleration as the magnetic field can be derived from Thomas precession due to Coulomb acceleration.
...
Anyhow it's fairly self evident and I realized it independently, as now have you.
...snipped yet another statement of Thomas precession that makes Eggs Ackley wrong...
You remain wrong - I have realized the actual physics, i.e. the gravitomagnetic field has nothing to do with Thomas precession.
Gravitoelectromagnetism
Quote:
Gravitoelectromagnetism, abbreviated GEM, refers to a set of formal analogies between the equations for electromagnetism and relativistic gravitation; specifically: between Maxwell's field equations and an approximation, valid under certain conditions, to the Einstein field equations for general relativity.
As I said in What is the magnetic field caused by Thomas precession of a Foucault pendulum?
Quote:
Thomas precession is not part of the mathematical structure of the Lorentz group.
It is a consequence of applying the mathematical structure of the Lorentz group to spinning objects, i.e. treating then relativistically. So when we do this to a Foucault pendulum:
(more emphasis added since you did not understand it the first time)
First asked 24th April 2013 - 2 days and counting.

Eggs Ackley, you have an couple of unsupported assertions.
Firstly: "the magnetic field can be derived from Thomas precession due to Coulomb acceleration.
As stated this is nonsense because Thomas precession is never due to Coulomb acceleration" - Thomas precession.
Please cite your sources for this magnetic field = Thomas precession + Coulomb acceleration" assertion.
First asked 26 April 2013 - 0 days and counting.

Secondly: "that can be similarly derived as a consequence of the Thomas precession due to gravitational acceleration" is also nonsense as stated since Thomas precession is not a gravitational effect.
Please cite your sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
First asked 26 April 2013 - 0 days and counting.
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Old 25th April 2013, 04:35 PM   #59
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Originally Posted by Eggs Ackley View Post
Bergstrom covers this in the paper that I linked to. Sorry it's behind a paywall.
The Bergstrom paper (On the origin of the magnetic field) was published in 1973.
By now (40 years later!) this ground breaking paper should be in textbooks. Can you cite these textbooks instead, Eggs Ackley?
By now (40 years later!) this ground breaking paper should have hundreds of citations (many publicly available). Can you cite some of these papers instead, Eggs Ackley?

Otherwise we have a suspiciously obscure paper. It is in a well established, peer-reviewed journal (Il Nuovo Cimento B). However we have to ask why A. Bergström (at the time in Stockholm)
  • Choose to publish there instead of a more important and relevant journal such as Physical Review Letters.
  • Has ony 3 papers published there (1969, 1973 and 1975)
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Old 25th April 2013, 04:54 PM   #60
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Originally Posted by Eggs Ackley View Post
Here is another take on the existence rotational pseudoforces due to Thomas precession, from Robert G. Littlejohn's course material linked in the wikipedia article linked by RC:

http://bohr.physics.berkeley.edu/cla...s/thomprec.pdf
Wow - you read Thomas precession , Eggs Ackley !
What your quote mining, Eggs Ackley, missed out was:
Quote:
In particular, we can examine vectors that have been Fermi-Walker transported along the world line of the particle over a period of the motion, and compare them to their original values. If we do this with the parallel transported frame, we find in general that the parallel transported frame after a period of the motion is related to the original frame by some rotation. This is in spite of the fact that the parallel transported frame is "rotationless," without centrifugal forces.
It is the parallel transported frame where there is no "rotation" and thus no centrifugal forces. When you compare the frames there is rotation and thus centrifugal forces.
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Old 25th April 2013, 08:17 PM   #61
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Originally Posted by Reality Check View Post
You remain wrong - I have realized the actual physics, i.e. the gravitomagnetic field has nothing to do with Thomas precession.
Gravitoelectromagnetism


As I said in What is the magnetic field caused by Thomas precession of a Foucault pendulum?

(more emphasis added since you did not understand it the first time)
First asked 24th April 2013 - 2 days and counting.



Eggs Ackley, you have an couple of unsupported assertions.
Firstly: "the magnetic field can be derived from Thomas precession due to Coulomb acceleration.
As stated this is nonsense because Thomas precession is never due to Coulomb acceleration" - Thomas precession.
Please cite your sources for this magnetic field = Thomas precession + Coulomb acceleration" assertion.
First asked 26 April 2013 - 0 days and counting.

Secondly: "that can be similarly derived as a consequence of the Thomas precession due to gravitational acceleration" is also nonsense as stated since Thomas precession is not a gravitational effect.
Please cite your sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
First asked 26 April 2013 - 0 days and counting.

From the Bergstrom abstract (here: http://link.springer.com/article/10.1007%2FBF02895716# ) (emphasis added):

On the origin of the magnetic field

A. Bergström

Summary


The nature of the magnetic field is discussed. In the customary descriptions, the existence of the magnetic field is either axiomatically introduced through the Maxwell equations, or enters in the form of an additional term to the electric force in a moving system resulting from the Lorentz transformation of the force vector. The present paper studies the latter approach in a new way by performing it in two steps, and describes the magnetic force as a Coriolis force resulting from the Thomas rotation caused by the electric force. The Larmor theorem, the vector-potential concept, and the quantum nature of the electromagnetic field are also discussed in terms of this novel approach.

(end of Bergstrom abstract)

Also, here is a quote from the penultimate paragraph of Bergstrom. (I can't do the equations properly here.):

"Although here studied in the electromagnetic case, the principle outlined is not limited to this case. Thus the existence of any force G, be it electric, gravitational, strong or other, and governed by any set of equations or distance dependence, will according to the deduction in eqs (8) through (13) imply the existence of a corresponding velocity dependent force
H = u x (v x G/c^2) in a system in relative motion."
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Old 25th April 2013, 08:34 PM   #62
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Originally Posted by Reality Check View Post
Wow - you read Thomas precession , Eggs Ackley !
What your quote mining, Eggs Ackley, missed out was:

It is the parallel transported frame where there is no "rotation" and thus no centrifugal forces. When you compare the frames there is rotation and thus centrifugal forces.
I disagree with your interpretation. I wonder if Sol Invictus would agree with you here. I hope he will weigh in on this.

It seems clear to me that Littlejohn is simply saying that the parallel transported frame after an orbit (i.e. a period of the motion) has rotated by some amount compared to its initial orientation, in spite of that there are no centrifugal forces in it.

It doesn't really matter how you interpret Littlejohn in my analysis of the problem ( http://arxiv.org/abs/1108.4343 ) because I only use the Thomas precession of inertial frames as "seen" from the Coulomb-accelerated test particle rest frame. Obviously, there are no centrifigual or Coriolis forces present in inertial frames.
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Old 25th April 2013, 09:11 PM   #63
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Originally Posted by Eggs Ackley View Post
I disagree with your interpretation. I wonder if Sol Invictus would agree with you here.
The Thomas Precession course notes text is quite clear.
Quote:
In particular, we can examine vectors that have been Fermi-Walker transported along the world line of the particle over a period of the motion, and compare them to their original values. If we do this with the parallel transported frame, we find in general that the parallel transported frame after a period of the motion is related to the original frame by some rotation. This is in spite of the fact that the parallel transported frame is "rotationless," without centrifugal forces.
It is clear to anyone Littlejohn is simply saying that
  • Vectors are rotated by some amount compared to their initial orientation in the Fermi-Walker transported frame.
  • Another parallel transported frame is "rotationless," without centrifugal forces.
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Old 25th April 2013, 09:14 PM   #64
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Question Cite your credible sources for magnetic field = precession + gravitation acceleration

Originally Posted by Eggs Ackley View Post
From the Bergstrom abstract ...
As far as we know Bergström is just a random crank because his paper has been ignored for the last 40 years.

So I will amend my questions to emphasize that you need credible sources , i.e. referenced in textbooks or later papers:
Eggs Ackley, you have an couple of unsupported assertions.
Firstly: "the magnetic field can be derived from Thomas precession due to Coulomb acceleration.
As stated this is nonsense because Thomas precession is never due to Coulomb acceleration" - Thomas precession.
Please cite your credible sources for this magnetic field = Thomas precession + Coulomb acceleration" assertion.
First asked 26 April 2013 - 0 days and counting.

Secondly: "that can be similarly derived as a consequence of the Thomas precession due to gravitational acceleration" is also nonsense as stated since Thomas precession is not a gravitational effect.
Please cite your credible sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
First asked 26 April 2013 - 0 days and counting.

Last edited by Reality Check; 25th April 2013 at 09:21 PM.
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Old 25th April 2013, 10:37 PM   #65
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RC, there are three independent derivations by three different people (Bergstrom, Royer, and me). That is all I know of. The time you are wasting whining about reputable sources would be better spent looking at the derivations and finding faults with them. If this is so impossible that should not be hard to do. If you can't be bothered to do that, then you're welcome to your opinion but it doesn't matter to me.

Usually the acceleration causing (along with translational motion) a Thomas precession (e.g. in atomic spin-orbit coupling) is Coulombic. I don't understand what you mean when you say Coulomb acceleration can't cause T.P. Are you just meaning that it also takes a translation perpendicular to the acceleration? That is not an issue here. I suppose you could be nitpicking the word "cause". Strictly it doesn't "cause" it. It just is. Strictly, the magnetic force isn't a Newtonian force, either. It's a relativistic kinematic effect seen by certain observers. All this is entirely beside the point.

The acceleration has to be Coulombic in order to relate the magnetic force to the T.P. in order to obtain the right magnitude for the magnetic force. Actually the magnetic force can always be related to a Coulombic acceleration, without regard to viewing it as a consequence of T.P. That is not hard to show and I thought it was common knowledge.
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Old 28th April 2013, 02:48 PM   #66
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Question What is "Coulombic" about the Thomas precession of a Foucault pendulum

Originally Posted by Eggs Ackley View Post
RC, there are three independent derivations by three different people (Bergstrom, Royer, and me).
That does not mean anything unless you can show that these "three independent derivations" are correct or at least credible. There are many independant derivations that the Earth is flat !

The time that you are wasting whining about the lack of reputable sources would be better spent finding reputable sources such as textbooks or credibale papers.

There is nothing "Coulombic" about Thomas precession. You persist in ignoring what Thomas precession is:
[QUOTE]In physics the Thomas precession, named after Llewellyn Thomas, is a relativistic correction that applies to the spin of an elementary particle or the rotation of a macroscopic gyroscope and relates the angular velocity of the spin of a particle following a curvilinear orbit to the angular velocity of the orbital motion. It can be understood geometrically as a consequence of the fact that the space of velocities in relativity is hyperbolic, and so parallel transport of a vector (the gyroscope's angular velocity) around a circle (its linear velocity) leaves it pointing in a different direction, or understood algebraically as being a result of the non-associativity of the relativistic velocity-addition formula.[/QUOTE]
Thomas precession happens even without an electric field. It is not dependant on electric or magnetic fields.

But maybe I am wrong - you can easily show this by answering:
Eggs Ackley, what is "Coulombic" about the Thomas precession of a Foucault pendulum?
First asked 29 April 2013 - 0 days and counting.

P.S.
Eggs Ackley: What is the magnetic field caused by Thomas precession of a Foucault pendulum?
24th April 2013 - 5 days and counting.

Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + Coulomb acceleration assertion.
26th April 2013 - 3 days and counting.


Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
26th April 2013 - 3 days and counting.
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Old 28th April 2013, 02:58 PM   #67
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Originally Posted by Eggs Ackley View Post
RC, there are three independent derivations by three different people (Bergstrom, Royer, and me).
Also:
Who is Royer? Citations please.
Why should I think that you are anything other than just anther internet physics crank? Maybe you can list your published peer-reviewed papers?

ETA: I have found an Antoine Royer who seems to be a bit of a crank because he has a pre-print that imagines that the magnetic force is caused by Thomas rotations. That is insanely wrong since magnetic forces do not vanish in the clssical limit (no Thomas rotation). Simple example - a bar magnet that is at rest w.r.t. an observer still has a magnetic field.

ETA2:
Another sign of a crank pre-print is that this 2011 pre-print has not been published and has only one citation - you!
At first glance, ArXiv suggests even more crankiness - 5 pre-prints submitted by Antoine Royer sine 2003, no sign of publication, no peer-reviewed citations. But ADS has plenty of published works for Antoine Royer starting in 1967 and extending to 2005. This suggests a specific type of crank - the older scientist with strange ideas.

Last edited by Reality Check; 28th April 2013 at 03:26 PM.
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Old 28th April 2013, 08:20 PM   #68
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RC, does almost count with respect to getting published? I got two out of three favorable reviews for this one: http://adsabs.harvard.edu/abs/2010arXiv1009.0495L

I posted the reviews here: http://quantumskeptic.blogspot.com/2...-in-today.html


That paper got cited as it sits on arxiv, though, in the peer-reviewed literature. In the same journal that passed on publishing it, actually. Some people may have heard of the citer. It can be confirmed at the ADS link. (Click on Refereed Citations.)

Also the comment I wrote about the paper mentioned actually did get published in AJP.

Two others of my arxiv papers got cited in an article in European Journal of Physics last year.

This is all beside the point. This idea that the magnetic force is a kinematical consequence of the Thomas precession should only be obvious now that it's been pointed out. It's quite a simple argument to get to it. I expect it will be in the textbooks eventually but it takes a while. It's curious that it went nowhere after Bergstrom I admit.

BTW I don't think I ever said a Coloumb acceleration is necessary for there to be a Thomas precession. Any old acceleration will do, so long as it has a component cross-wise to the relative velocity. If I said otherwise it was contrary to my intention. However, a magnetic force on the other hand can always be related to an electrical acceleration. I don't think you will dispute that. I agree it's less than obvious this acceleration is Coulombic in the case of ferromagnetism, but for a classical current or for the interaction between two classical charges it's not hard to demonstrate.
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Old 28th April 2013, 09:57 PM   #69
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Originally Posted by Eggs Ackley View Post
RC, does almost count with respect to getting published?
Not at all. In fact it is the other way around - if you are rejected by a journal then your paper has enough flaws that at least 1 reviewer can see that it is wrong. As you say in your blog:
Quote:
Two of the reviews are quite positive but the third not. Naturally the editor decided against publication
(my emphasis added)
And there is the little problem of that pre-print being off-topic !

Originally Posted by Eggs Ackley View Post
That paper got cited as it sits on arxiv, though, in the peer-reviewed literature.
But not in a peer-reviewed paper - in a letter.
And citing a pre-print is bad practice as you should know. It is peer-reviewed papers in (hopefully high impact) scientific journals that count. One of the things that reviewers and editors)usually do is make sure the references are of good quality. Citing a pre-print is not so bad in letters since they are expected to be as up-to-date as possible.

Originally Posted by Eggs Ackley View Post
This idea that the magnetic force is a kinematical consequence of the Thomas precession should only be obvious now that it's been pointed out.
That idea that the magnetic force is a kinematical consequence of the Thomas precession is obviously physically nonsense for the reasons that have already been stated (magnetic force exists without Thomas precession).

Originally Posted by Eggs Ackley View Post
t's quite a simple argument to get to it
Why have you never stated that simple argument?

Originally Posted by Eggs Ackley View Post
BTW I don't think I ever said a Coloumb acceleration is necessary for there to be a Thomas precession.
BTW I ever said that you said a Coloumb acceleration is necessary for there to be a Thomas precession. That would make you seem extermely ignorant !



Read the questions that I have asked (and that so far you are incapable of answering):
  1. Eggs Ackley: What is the magnetic field caused by Thomas precession of a Foucault pendulum?
    24th April 2013 - 5 days and counting.
  2. Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + Coulomb acceleration assertion.
    26th April 2013 - 3 days and counting.
  3. Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
    26th April 2013 - 3 days and counting.
  4. Eggs Ackley: What is "Coulombic" about the Thomas precession of a Foucault pendulum?
    29 April 2013 - 0 days and counting.
Originally Posted by Eggs Ackley View Post
Any old acceleration will do,...
And you seem to be repeating your ignorance since Thomas precession has nothing to do with acceleration. It is a correction that is applied when a system has a relativistic velocity. There is angular momentum (not acceleration) involved because the system is rotating.

Last edited by Reality Check; 28th April 2013 at 10:04 PM.
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Old 28th April 2013, 10:45 PM   #70
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RC, from your wikipedia article on the Thomas precession:

Quote:
The composition of two Lorentz boosts which are non-collinear, results in a Lorentz transformation that is not a pure boost but is the product of a boost and a rotation. This rotation is called Thomas rotation, Thomas-Wigner rotation or Wigner rotation.
Two non-collinear boosts implies an acceleration.

You asked for my publications without regard to the present topic. Now you are moving the goal posts. Anyhow it is not all that far afield.

That citing paper is a commissioned review article, not an ordinary letter. It's by the author of some very popular physics textbooks.
http://en.wikipedia.org/wiki/David_J._Griffiths

I don't think he would have cited my paper unless he thinks it makes a contribution, and I know he's qualified to make that determination. He could easily have omitted it. No one would've noticed the omission.

Can you produce a quote of me saying a Coulomb acceleration is necessary for there to be a Thomas precession? If not, then I think you should drop it. If so, then it's my mistake that I have already said it was never intended.

The simple argument is stated here: http://arxiv.org/abs/1108.4343
I think I have posted that link already.


I have given the qualitative overview upthread recently.
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Old 29th April 2013, 01:56 PM   #71
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I've been meaning to mention that this part of one of my earlier posts (which fuelair kindly quoted not too far above) is mistaken:

"However another way to think about it that I have already figured out is how the anticentrifugal force looks to the children on the magic inertialess merry-go-round. They also think there is an attractive force present. They see the people standing in the park as orbiting around them, and can even calculate (if they are exceptionally smart children) what is the force law needed to hold the people in orbit, just as we can calculate the gravitational force law from the orbital motion of the moon."

That is entirely not what people see from a Thomas-precessing reference frame. They do not see the fixed stars circling around them the way we do from the rotating earth. Understanding how it really works is one thing that helped me I think really this time see my way through at least to some of the way that real forces can be kinematical consequences of relativity.

It's not difficult to describe what somebody in an accelerating spaceship will see out their window, with regards to the Thomas precession. Imagine that the spaceship is far out in space and let's say that the sun's position provides an approximation of an inertial reference frame with a coordinate system fixed with respect to the sun, and where the coordinate system is not rotating with respect to the stars. Also imagine that the spaceship is moving relative to the sun and constantly accelerating crosswise to the motion in such a way that the spaceship is moving in one plane that we could choose to be the plane of the ecliptic. Now imagine a giant field of gyroscopes placed in gigantic grid in the plane, with all of their axes tilted relative to the normal to the plane. For any observer who is either fixed or moving intertially, (i.e. moving at constant velocity including not turning), the gyroscope axes all stay still. The observer in the rocketship however sees the gyroscopes precessing, each with a precessional angular velocity that is given approximately (provided that the rocketship is not traveling too near the speed of light) as (cross velocity)x(radial acceleration)/(2 x c^2) where c is the speed of light, and where the cross velocity is the component of velocity that the rocketship has relative to the particular gyroscope that is not along the line-of-sight vector to the gyroscope, and the radial acceleration the rocketship acceleration component along that line of sight. This is a standard equation in electrodynamics or relativity textbooks, which is inexplicably absent from the wikipedia Thomas precession article repeatedly being linked by RC. It does however appear in the Littlejohn course notes material that is linked in that article, as Eq. (5.30).

Anyhow what that is trying to describe is that all of the gyroscopes are precessing at different rates depending on where they are relative to the rocketship position, and also the rates depend on how fast the rocketship is traveling and accelerating. If would have to be accelerating and/or traveling pretty fast for the effect to be noticable, but elementary particles very often travel quite fast and accelerate quite hard, especially in bound systems like an atom.

Sorry about the mistake. Correcting that is something that was enough to justify coming back, on its own. That part was not integral or essential to my overall argument, so far as I can tell.

Later on possibly today I will try to explain again how imagining being in the point of view of a Coulomb-accelerating charged particle, and trying to calculate what your motion is from the point of view of a non-accelerating observer is a way to obtain the magnetic force law without having to invoke any magnetic field. It's a nice way to visualize how the magnetic field and force have to come about, but more importantly, it seems to also predict two other forces one of which seems like the strong force. I suspect the other may correspond to the weak force but I haven't got as far as checking that yet. Also later on, although probably not today, I will try to explain how that predicted centrifugal-like force that seems like the strong force can actually seemingly already be found in electrodynamics if you know where to look. This part is already posted on arxiv. See section VI of this: http://arxiv.org/abs/1108.4343v5 . It shows how the magnetic part of the radiative field can be strongly attractive on a charge at close range, when the particle doing the radiating is being Coloumb accelerated at extreme close range, and how the relative signs of the field-causing charge and that being acted on don't affect whether the force is repulsive or attractive. It is always attractive.
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Old 29th April 2013, 02:54 PM   #72
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Question Can you quote me stating that you stated Coulomb acceleration gives Thomas precession

Originally Posted by Eggs Ackley View Post
Two non-collinear boosts implies an acceleration.
No they do not. They imply two non-collinear boosts, e.g. a shift in coordinates in the x direction followed by a shift in coordinates in a y direction. Thay are coordinate transformations, not movements of a object.

Originally Posted by Eggs Ackley View Post
You asked for my publications without regard to the present topic.
I asked for your publications in this thread. This thread is about your assertion (which is looking more and more like a fantasy) that the magnetic force is a result of Thomas precession + Clomb attraction.

Originally Posted by Eggs Ackley View Post
Can you produce a quote of me saying a Coulomb acceleration is necessary for there to be a Thomas precession?
Eggs Ackley: Can you quote me stating that you stated that a Coulomb acceleration is necessary for there to be a Thomas precession?
30 April 2013 - 0 days and counting.

There is no such statement in:
  1. Eggs Ackley: What is the magnetic field caused by Thomas precession of a Foucault pendulum?
    24th April 2013 - 6 days and counting.
  2. Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + Coulomb acceleration assertion.
    26th April 2013 - 4 days and counting.
  3. Eggs Ackley: Cite your credible sources for this magnetic field = Thomas precession + gravitation acceleration assertion.
    26th April 2013 - 4 days and counting.
  4. Eggs Ackley: What is "Coulombic" about the Thomas precession of a Foucault pendulum?
    29 April 2013 - 1 days and counting.
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Old 29th April 2013, 03:09 PM   #73
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Question A simple scenerio that seems to debunk the magnetic force origin assertion

Originally Posted by Eggs Ackley View Post
The simple argument is stated here: http://arxiv.org/abs/1108.4343.
The simple argument in the pre-print The Magnetic Force as a Kinematical Consequence of the Thomas Precession can be shown to be bogus by an even simpler argument that an undergraduate (or maybe even a high shool!) student can understsnd.

Consider a wire carrying a current I. Place a test particle with a charge q a distance r from the wire. Can you answer the following questions, Eggs Ackley
  • What is the magnitude and direction of the Thomas precession in this system?
  • What is the magnitude and direction of the magnetic force exterted on the test particle by this Thomas precession?
The wire is electrically neutral (no Coulomb acceleration).
You cannot start with the classical magnetic force because your assertion is that the magnetic force is caused by Thomas precession + Coulomb acceleration only.

Last edited by Reality Check; 29th April 2013 at 03:23 PM.
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Old 29th April 2013, 04:07 PM   #74
Eggs Ackley
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RC, that's a fair question to which I have the answer. But it's really only the standard way of looking at things to get the electrostatic acceleration.

So you have the current flowing in the neutral wire, but in the rest frame of the current carriers in the wire, the spacing of metal ions in the wire is Lorentz-contracted, so an observer traveling parallel to the wire and at the same speed as the current carriers sees a net charge density in the wire. So there is a Coulomb acceleration of the test charge in the current carriers rest frame that goes over exactly to the magnetic force when you Lorentz transform to the lab frame. This should not be controversial. When the magnetic force is acting, it must be accelerating a charge. This same acceleration seen from the rest frame of the test particle is also directly relatable to a Thomas precession, and everything comes out neatly that this Thomas precession is another way of accounting for the magnetic force.
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Old 29th April 2013, 04:35 PM   #75
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Originally Posted by Eggs Ackley View Post
RC, that's a fair question to which I have the answer. But it's really only the standard way of looking at things to get the electrostatic acceleration. ...
Which is totally wrong.
You have the current flowing in the neutral wire. So any observer outside the wire sees no charge from anything in the wire and no "electrostatic acceleration". That is what neutral means.

A simple scenerio that seems to debunk the magnetic force origin assertion
You need to show that
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Old 29th April 2013, 05:53 PM   #76
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RC, it is in the rest frame of the current carriers that the wire is not electrically neutral.

Seriously, if you have something moving in the wire that's charged, against a background of the ions that is stationary and charged oppositely, then if the total is neutral in one inertial frame (the lab frame say) then it can't be electrically neutral when seen by an observer who moves parallel to the wire at the speed of the current carriers. The charge densities of both the current carriers and the ion lattice are different from those seen by the lab frame observer, and not in such a way as to preserve the neutrality of the wire.
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Old 29th April 2013, 06:19 PM   #77
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Question A simple scenerio that seems to debunk the magnetic force origin assertion

Originally Posted by Eggs Ackley View Post
RC, it is in the rest frame of the current carriers that the wire is not electrically neutral.
Eggs Ackley, the wire is electrically neutral for the test particle in all frames.
But since you are going on about frames of reference, we need to specify them!

Consider a wire carrying a current I.
Place a test particle with a charge q a distance r from the wire.
The test particle is at rest with respect to the wire.
The charge carriers in the wire have a velocity of v.
Can you answer the following questions, Eggs Ackley
  1. What (if any) is the electrical charge of the wire?
  2. What is the magnitude and direction of the Thomas precession in this system?
  3. What is the magnitude and direction of the magnetic force exerted on the test particle by this Thomas precession?
The wire is electrically neutral (no Coulomb acceleration on the test particle unlkess you can show otherwise in question 1).
You cannot start with the classical magnetic force because your assertion is that the magnetic force is caused by Thomas precession + Coulomb acceleration only.

Last edited by Reality Check; 29th April 2013 at 06:29 PM.
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Old 29th April 2013, 06:25 PM   #78
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The Thomas precession comes in when you consider that an observer sees who is moving and accelerating along with the test particle. The complicated part of it is that that observer sees the source particle Thomas precessing in its rest frame (we can suppose it is sitting next to a neutral gyroscope in free space) where there is no magnetic force, but he also sees another gyroscope uniformly translating relative to the source particle as Thomas precessing with a different rate. If we take the second gyroscope that is uniformly translating relative to the source particle to be stationary in another frame, where we see the magnetic field and force, then we can equate that magnetic field directly with the difference between the two Thomas precession angular velocities. This is what I do in my preprint.

The Thomas precession angular velocity for small v/c is basically (see Littlejohn, for example) v x a/(2c^2). On the other hand, the magnetic field from a moving (not too fast) charge is q v x r/(cR^3), with R=|r|. But if the acceleration is Coulombic, then a = q^2 r /R^3, and then if we substitute this for a in the first equation we get something very similar in form to the magnetic field just from the Thomas angular velocity. Getting this to line up exactly with the magnetic force is a little bit tricky because as I said it is actually the difference between two Thomas precession angular velocities that accounts for it exactly and that took me quite a while to get to. That's in my preprint where it belongs. I'm still working on a better version that will show it more convincingly, using successive Lorentz transformations of position entirely.
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Old 29th April 2013, 06:39 PM   #79
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Originally Posted by Eggs Ackley View Post
The Thomas precession comes in when you consider that an observer sees who is moving and accelerating along with the test particle.
See my previous post.
  • The test particle is not moving
  • The test particle is not accelerating
  • The observer is the test particle!
    Or if you like the observer is sitting on the test particle, is not moving and is not accelerating .
Thomas precession does not come in at with "moving and accelerating".
Thomas precession comes in with considering an observer who is observing a rotating object. When you have a spinning body and apply SR then you get Thomas precession. No spinning body then no Thomas precession.
So the electrons in the wires are undergoing Thomas precession but the wire itelf is not nor is the test particle.

You should know this but Thomas interaction energy
Quote:
In 1926 Llewellyn Thomas relativistically recomputed the doublet separation in the fine structure of the atom.[1] Thomas precession rate, , is related to the angular frequency of the orbital motion, , of a spinning particle as follows [2][3]
where is the Lorentz factor of moving particle.
(my emphasis added)

But ...
Eggs Ackley: Please cite the textbook or credible paper where the Thomas precession rate is defined for a non-spinning particle or body.

Last edited by Reality Check; 29th April 2013 at 06:46 PM.
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Old 29th April 2013, 06:51 PM   #80
Eggs Ackley
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Originally Posted by Reality Check View Post
Eggs Ackley, the wire is electrically neutral for the test particle in all frames.
But since you are going on about frames of reference, we need to specify them!

Consider a wire carrying a current I.
Place a test particle with a charge q a distance r from the wire.
The test particle is at rest with respect to the wire.
The charge carriers in the wire have a velocity of v.
Can you answer the following questions, Eggs Ackley
  1. What (if any) is the electrical charge of the wire?
  2. What is the magnitude and direction of the Thomas precession in this system?
  3. What is the magnitude and direction of the magnetic force exerted on the test particle by this Thomas precession?
The wire is electrically neutral (no Coulomb acceleration on the test particle unlkess you can show otherwise in question 1).
You cannot start with the classical magnetic force because your assertion is that the magnetic force is caused by Thomas precession + Coulomb acceleration only.
That's not a hard problem. With the test charge stationary relative to the wire, and wire is neutral in that frame then there is no force on the test charge of any kind and it just sits there. There is no Thomas precession even from the point of view of the test charge. There is a magnetic field but it's not doing anything. It isn't until it acts that there's a Thomas precession. That's in part why I prefer to say that the Thomas precession is an explanation for the magnetic force rather than for the magnetic field. In classical physics if not in quantum theory, magnetic and even electrical fields are convenient concepts, but don't have to be taken as real, at least since Fokker.

If we start moving the test charge relative to the wire ion lattice, then we have a magnetic force but no electric force in the frame where the wire metal ions are stationary. But on the other hand in the test charge's own instantaneous (inertial) rest frame it is not moving so why is it accelerating? There is no magnetic force on it in it's rest frame, because a magnetic force requires the v in v x B to be nonzero. If the wire is electically neutral in this frame (it is of course not actually) then it can't generate any electric force either and so the test particle wouldn't accelerate. And yet it does. That's because the wire is not electrically neutral in the test particle rest frame when the test particle is moving (properly so as to feel a force) relative to the wire.
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