Sione Posted January 29, 2009 Posted January 29, 2009 (edited) The long and short of it is that a single point will not have motion until you introduce another point to to compare movement with. Motion is a comparative measurement (as opposed to mass which is an intrinsic measurement) meaning you need more than one thing to do a comparison. I agree' date=' thought it is more that "motion" loses meaning without the 'distance'. Whether it is acceleration or velocity, motion is always some 'distance over time', so without distance equation does not compute, or perhaps equals zero. The distance is the factor that is missing when you have only one point, which interestingly leads us to some peculiarities and makes us wonder about equations that have velocity in them, like Lorenz force: F=q[E + (v x B)']. Imagine, electron is moving with velocity 'v' and have magnetic field that is proportional to it's charge and velocity. Velocity? ..relative to what? Aether? Now, imagine two electrons traveling in parallel with the same velocity. Again, relative to what? How could it be their relative velocity does not matter, but some "individual" velocity relative to some absolute reference frame, some aether, matters? Such equations actually suggest existence of an Aether, what do we do with that? Edited January 29, 2009 by Sione
npts2020 Posted January 30, 2009 Posted January 30, 2009 Well, talking about aether is introducing a sticky wicket. If you have it then you have the frame of reference required for measuring motion. Even Einstein spent a great deal of time trying to figure out whather or not there was such a thing and AFAIK nobody has shown it conclusively to be true or false.
Sisyphus Posted January 30, 2009 Posted January 30, 2009 The velocity in those equations is relative velocity. There is no such thing as absolute velocity. And aether is conclusively disproven, by confirmation of special relativity.
Sione Posted January 31, 2009 Author Posted January 31, 2009 The velocity in those equations is relative velocity. There is no such thing as absolute velocity. Well' date=' I do not say I like it either, but the strength of the magnetic field in those equations is not proportional to their relative velocities but their individual velocities. Two electrons traveling in parallel with the same velocity, without any relative velocity, will attract each other more the faster they are moving. Do you know about this? And aether is conclusively disproven, by confirmation of special relativity. There is no such thing as ultimate certainty, some theories work, some don't, some that worked before are replaced with new that work better... "Aether" is only abstract concept of some analog medium. You can disprove certain theory about it, but not the concept itself. Aether then, is rather a fact, in a sense that there is no such thing as vacuum. Well' date=' talking about aether is introducing a sticky wicket. If you have it then you have the frame of reference required for measuring motion. Even Einstein spent a great deal of time trying to figure out whather or not there was such a thing and AFAIK nobody has shown it conclusively to be true or false. [/quote'] Depends how you define aether, I am showing on a practical, every day, real-world, testable example how equations imply the existence of some absolute reference frame, we do not need to call it "Aether", but it's there.
Sisyphus Posted January 31, 2009 Posted January 31, 2009 Again, that is incorrect. The velocity is relative. The strength of the magnetic field you experience is dependent on your velocity relative to the electron.
Sione Posted January 31, 2009 Author Posted January 31, 2009 Again, that is incorrect. The velocity is relative. The strength of the magnetic field you experience is dependent on your velocity relative to the electron. What? What electron? What is velocity relative to again, look: F= q(v x B) ? You seem to not know, can you respond to this: - "Two electrons traveling in parallel with the same velocity, without any relative velocity, will attract each other more the faster they are moving." Do you know about this, you do not know or you claim is false?
swansont Posted January 31, 2009 Posted January 31, 2009 What? What electron? What is velocity relative to again, look: F= q(v x B) ? You seem to not know, can you respond to this: - "Two electrons traveling in parallel with the same velocity, without any relative velocity, will attract each other more the faster they are moving." Do you know about this, you do not know or you claim is false? Electrons, or electrons in wires? Two electrons, by themselves, will repel each other.
Sisyphus Posted January 31, 2009 Posted January 31, 2009 (edited) What? What electron? What is velocity relative to again, look: F= q(v x B) ? You seem to not know, can you respond to this: - "Two electrons traveling in parallel with the same velocity, without any relative velocity, will attract each other more the faster they are moving." Do you know about this, you do not know or you claim is false? That equation describes the force on a charged particle as it moves through a magnetic field. The v in the equation is the particle's velocity relative to the field. Moving the particle or moving the source of the field in the opposite direction has the same effect. There is no absolute velocity. Your bold text is, in fact, false. Two isolated electrons with no relative velocity will simply repel one another electrostatically. "The faster they are moving" is meaningless, inasmuch as there is no such thing as absolute velocity. Parallel currents in wires is a different situation, inasmuch as they are moving relative to the ions in the wires. Edited January 31, 2009 by Sisyphus
Sione Posted January 31, 2009 Author Posted January 31, 2009 (edited) Electrons' date=' or electrons in wires? Two electrons, by themselves, will repel each other. [/quote'] Yes, they will repel due to electrostatic field, I just did not want to complicate. What I said is they will "repel less", "attract more" the faster they are going. Free electrons and electrons in wires alike, thought it is much harder to test it with free electrons because they will repel quite strongly as velocities gets lower from that of speed of light, it is kind of hard to have them travel in parallel, but the effect could be measured regardless. I mean, look at the equations, they simply just work that way, as if there is some absolute reference frame. That equation describes the force on a charged particle as it moves through a magnetic field. The v in the equation is the particle's velocity relative to the field. Moving the particle or moving the source of the field in the opposite direction has the same effect. There is no absolute velocity. Yes' date=' it is related/proportional to magnetic field, only it is not "through a magnetic field", in this case, but along with it, "in it", without any relative velocity. Ok, let me explain, look at the other part and consider the whole situation, we have this then: F= q(v x B) B= v x q*k*d/r^2 It should be more obvious to see the strength of magnetic field is proportional to velocity and distance. Now, it is a basic physics knowledge that magnetic field forms when charge is moving, it tell us magnetic field is zero when charge is not moving and we can see the strength increases as velocity increases, right? Magnetic potential vector field increases with velocity, not relative velocity. Perhaps I got the equations wrong? Your bold text is, in fact, false. Two isolated electrons with no relative velocity will simply repel one another electrostatically. "The faster they are moving" is meaningless, inasmuch as there is no such thing as absolute velocity. Parallel currents in wires is a different situation, inasmuch as they are moving relative to the ions in the wires. 1.) "...relative to the field" 2.) "...relative to the ions in the wires" First you said velocity is relative to field then you said it is relative to wire, which one then? If it is relative to field, then when two fields travel without any relative velocity there should not be any attraction, right? But there is, so obviously there is some absolute reference frame, as far as charged particles are concerned anyway. http://www.magnet.fsu.edu/education/tutorials/java/parallelwires/index.html Edited January 31, 2009 by Sione
Sisyphus Posted January 31, 2009 Posted January 31, 2009 Now, it is a basic physics knowledge that magnetic field forms when charge is moving, it tell us magnetic field is zero when charge is not moving and we can see the strength increases as velocity increases, right? Magnetic potential vector field increases with velocity, not relative velocity. Perhaps I got the equations wrong? This is the key issue. It is relative velocity. There is no such thing as "velocity" in itself, only measured with respect to something else. A magnetic field is what you experience when you move relative to an electrostatic field. Or vice versa, if the electric field (that is, the charged particle) moves relative to you. (Since there is no absolute reference frame, the situations are identical.) That is what is meant by "a magnetic field forms when charge is moving." Moving relative to what the field is acting on.
thief Posted January 31, 2009 Posted January 31, 2009 Thief here... In previous post, I took away anything that had a number on it. I was trying to express the singularity. The discussion quickly reverted to motion equations. Then someone mentioned aether. True enough, the notion of aether has faded into disbelief, but allow me to bring it up in a different view. The singularity must have existed. Reversing all motion would bring us to that one point. But what if that one point need not be solitary? Multiply the point into infinity. Simply don't allow movement. Could aether be described as a universe pending a spark?
Sione Posted January 31, 2009 Author Posted January 31, 2009 (edited) I can not explain it if you refuse to know about it. Please, answer this: 1.) "...relative to the field" 2.) "...relative to the ions in the wires" First you said velocity is relative to field then you said it is relative to wire, you have to decide on only one opinion, which one? This is the key issue. It is relative velocity. There is no such thing as "velocity" in itself' date=' only measured with respect to something else. A magnetic field is what you experience when you move relative to an electrostatic field. Or vice versa, if the electric field (that is, the charged particle) moves relative to you. (Since there is no absolute reference frame, the situations are identical.) That is what is meant by "a magnetic field forms when charge is moving." Moving relative to what the field is acting on. [/quote'] Do you not believe in Lorentz force? F= q(v x B); B= v x q*k*d/r^2; Here is java applet of two parallel wires, is velocity relative to wire or field? http://www.magnet.fsu.edu/education/tutorials/java/parallelwires/index.html Why are you so stubborn? You just keep repeating your opinion and you have equations right in front of you. Why don't you look it up on the Internet and show me any experiment that shows otherwise. Alternatively, you may look up studies about electron beams and see if they found any attraction there. - "A magnetic field is what you experience when you move relative to an electrostatic field." No, magnetic field is this: B= v x q*k*d/r^2. And yes, WHEN you are moving relative to it, but how do you explain attraction when they DO NOT have any relative speed, when they travel in parallel? - "This is the key issue. It is relative velocity." Ok, tell me then what is relative velocity of two particles traveling in parallel? Edited January 31, 2009 by Sione
swansont Posted February 1, 2009 Posted February 1, 2009 Yes, it is related/proportional to magnetic field, only it is not "through a magnetic field", in this case, but along with it, "in it", without any relative velocity. Ok, let me explain, look at the other part and consider the whole situation, we have this then: F= q(v x B) B= v x q*k*d/r^2 It should be more obvious to see the strength of magnetic field is proportional to velocity and distance. Now, it is a basic physics knowledge that magnetic field forms when charge is moving, it tell us magnetic field is zero when charge is not moving and we can see the strength increases as velocity increases, right? Magnetic potential vector field increases with velocity, not relative velocity. Perhaps I got the equations wrong? I don't see the relativistic correction.
Sione Posted February 2, 2009 Author Posted February 2, 2009 (edited) I don't see the relativistic correction. Me neither. Wrong equation? Can you give us correct one? What's worse that is exactly how real world experiments work. It is not that I want you to accept existence of absolute reference frame, I want explanation too. I mean, the mere fact that we have ELECTRON BEAMS (cathode ray in TV), means that electrons can actually travel in parallel, for some time at least. We should know from practical electronics the amount of repulsion/attraction of electrons in such beam, would that prove it? Thought, experiment with two parallel wires is actually the same, only the existence of wires makes people think the velocity is relative to wires, but equations suggest that is not the case and experiments with free electrons should make that clear. Parallel wires and magnetic fields: http://www.magnet.fsu.edu/education/tutorials/java/parallelwires 1.) velocity relative to field ? 2.) velocity relative to wires" ? So, what do we do, any idea? I have links that talk about electron attraction. This is not unknown at all, in chemistry and QM we accept for granted electron coupling, so it is not a question of whether electrons can attract, but whether that implies the existence of some 'absolute reference' frame or not. Edited February 2, 2009 by Sione
swansont Posted February 2, 2009 Posted February 2, 2009 Parallel wires and parallel beams are different, which is why I asked the question. There is no electrostatic force in the wires in their rest frame, which is not true of a beam. IIRC, you have to account for the length contraction of the beams, which increases their charge density and the electrostatic repulsion, and cancels the increased magnetic attraction. This effect is also present when you look at the wires. There is no preferred frame.
Sione Posted February 2, 2009 Author Posted February 2, 2009 (edited) Parallel wires and parallel beams are different' date=' which is why I asked the question. There is no electrostatic force in the wires in their rest frame, which is not true of a beam. [/quote'] I see you are saying they are different, but equations work equally for both and experiments confirm equations. Anyway, what do you say in reality the velocity is relative to: Free electrons: a. velocity relative to field? b. velocity relative to ....? Electrons in wire: a. velocity relative to field? b. velocity relative to wires? IIRC, you have to account for the length contraction of the beams, which increases their charge density and the electrostatic repulsion, and cancels the increased magnetic attraction. This effect is also present when you look at the wires. There is no preferred frame. I accounted for everything and all the experiments confirm electron attraction increases due to "absolute velocity", not their relative velocity, since they attract more the faster they are going ALONG each other, in parallel, without any relative velocity. I agree, of course there is no "absolute velocity", it seems velocity is relative to "FixedStars", kind of like "Aether". Can you give any reference, experiments or links that show otherwise? Edited February 2, 2009 by Sione
swansont Posted February 2, 2009 Posted February 2, 2009 I accounted for everything and all the experiments confirm electron attraction increases due to "absolute velocity", not their relative velocity, since they attract more the faster they are going ALONG each other, in parallel, without any relative velocity. I agree, of course there is no "absolute velocity", it seems velocity is relative to "FixedStars", kind of like "Aether". You have given no references that support this. They have all been for parallel wires, which is not the same thing. Q=0 for wires. Can you give any reference, experiments or links that show otherwise? I've seen it worked out but can't find the link at the moment. But E^2-B^2 is a Lorentz invariant.
Sione Posted February 5, 2009 Author Posted February 5, 2009 (edited) Well, my intention was to have conversation where we could try to find conclusion together, not be convincing each other of anything, but sharing information about it. You seem confident in your current opinion and you do not seem to want to research the subject further, which is fine. Anyway, this is my reference, together with the whole WWW: - "Strength of magnetic attraction between two electrons traveling without any relative velocity is proportional to their individual velocity." Equations are clear about that: F= q(v x B); B= v x q*k*d/r^2 Experiments are clear about that: http://www.magnet.fsu.edu/education/tutorials/java/parallelwires/index.html To me, this paradox seem very simple and obvious, easy to demonstrate, confirmed in experiments and equations in everyday life. I do not mean to claim or insist on any particular conclusion, nor to have empty argument, so I can continue to research it by myself and you are free to join and share with me how do you explain the paradox to yourself. Edited February 5, 2009 by Sione
Sisyphus Posted February 5, 2009 Posted February 5, 2009 It's not a paradox. A magnetic field is an electrostatic field experienced in a reference frame in which the source has a nonzero velocity. In the reference frame in which that very same source has a velocity of zero, there is no magnetic field.
Sione Posted February 6, 2009 Author Posted February 6, 2009 It's not a paradox. A magnetic field is an electrostatic field experienced in a reference frame in which the source has a nonzero velocity. In the reference frame in which that very same source has a velocity of zero' date=' there is no magnetic field. [/quote'] Two electrons traveling next to each other, without any relative velocity, are in the SAME reference frame. The "observer" is second reference frame and everything else that is moving around is in its own reference frame. Only, magnetic fields do not care about particular people that observe them. Observer, or any other reference frame, can move as they wish, but electrons do not care, they will feel magnetic attraction ONLY if they are actually moving(through what?), not if people run around while looking at electrons, that doesn't produce any magnetic fields around them. Electrons do not care about reference frames, but the one frame they are in together since they are like one object if they keep the same distance. In that reference frame their relative velocity to each other is zero, but their relative velocity to something else obviously increases the strength of magnetic field. It is not observer because it does not work the other way around. Not really a paradox, only some bug in the theory. Maxwell, Lorentz, Ampere... they were all life-long supporters of some kind of absolute reference frame, we use those equations and they work. On the other hand we have Einstein's "Lorentz transformations" that simply do not apply where they should be used - to model electromagnetic interaction. Look how Wikipedia describes it: Lorentz transformation: - "They form the mathematical basis for Albert Einstein's theory of special relativity. In 1905 Einstein derived them under the assumptions of the principle of relativity and the constancy of the speed of light in any inertial reference frame." The point is, if there was absolute frame, that would not change results in SR at all, so I do not see what is the big deal about it since it could not be proven or refuted from SR point of view anyway, SR would be blind to it and everything will work just the same, except for magnetic fields that is.
Sisyphus Posted February 6, 2009 Posted February 6, 2009 Ok, read this: http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html 1
swansont Posted February 6, 2009 Posted February 6, 2009 Well, my intention was to have conversation where we could try to find conclusion together, not be convincing each other of anything, but sharing information about it. You seem confident in your current opinion and you do not seem to want to research the subject further, which is fine. Anyway, this is my reference, together with the whole WWW: To me, this paradox seem very simple and obvious, easy to demonstrate, confirmed in experiments and equations in everyday life. I do not mean to claim or insist on any particular conclusion, nor to have empty argument, so I can continue to research it by myself and you are free to join and share with me how do you explain the paradox to yourself. Well, I seriously doubt searched the whole WWW, and your the reference you've cited repeatedly is entitled PARALLEL WIRES, which means that it doesn't apply to the circumstance of parallel beams of electrons (or protons). If you can't recognize that, there is no point in discussing this further. Merged post follows: Consecutive posts mergedOk, read this: http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html Bingo! There it is. The mistake was in ignoring the relativistic Fitzgerald-Lorentz contraction
moth Posted February 6, 2009 Posted February 6, 2009 Ok, read this: http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html if an electric field looks like a magnetic field depending on the direction of motion of the reference frame, does that mean photons are coming at us from two directions at once? (maybe past and future?)
Sione Posted February 6, 2009 Author Posted February 6, 2009 Well' date=' I seriously doubt searched the whole WWW, and your the reference you've cited repeatedly is entitled PARALLEL WIRES, which means that it doesn't apply to the circumstance of parallel beams of electrons (or protons). If you can't recognize that, there is no point in discussing this further. [/quote'] I'm talking about two electrons, wire or no wire. What I was referring to is that every single article that talks about it, confirms it, so there is no need to copy/paste all the links there are, it will be enough if someone brings just one link that refutes it. Observer, or any other reference frame, can move as they wish, but electrons do not care, they will feel magnetic attraction ONLY if they are actually moving(through what?), not if people run around while looking at electrons, that doesn't produce any magnetic fields around them. Ok' date=' read this: http://galileo.phys.virginia.edu/cla...el_el_mag.html Bingo! There it is. The mistake was in ignoring the relativistic Fitzgerald-Lorentz contraction [/quote'] What do you mean? That does not address the problem, that's about wires and Amperes law does the same thing with absolute reference frames. None of that can model magnetic field interaction of individual moving charges properly. Why would we use that in a first place? Nothing is missing from classic equations, they already work very well with absolute frames. - Do you think magnetic field forms around electron flying past stationary neutron? - Do you think magnetic field forms around stationary electron when neutron flies past it?
Klaynos Posted February 6, 2009 Posted February 6, 2009 I want to take a moment to clarify a few very important points, that are clearly stated when you solve Maxwell's equations. Electrons moving in wires are NOT the same as free electrons moving, wires have no net charge, electron beams do. Two free electrons moving parallel to each other feel NO magnetic fields due to each other. Maxwell's electrodynamics was the first relativistic theory, he just didn't realise it at the time, and unluckily he was a very busy man and died quite young before he had a chance to realised just what he had done. Any electromagnetism book will tell you these things, they are VERY well understood. There is no requirement for an absolute frame. Merged post follows: Consecutive posts merged - Do you think magnetic field forms around electron flying past stationary neutron? - Do you think magnetic field forms around stationary electron when neutron flies past it? In what frame? In both cases in the frame of the neutron there is a magnetic field, although you will need some test charge to be able to observe this, which the neutron is not.
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