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| Tags: acderlating, gravity, mass, radiate, waves |
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#11
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Bill Hobba wrote: "shevek" wrote in message oups.com... shevek wrote: Bill Hobba wrote: I have given the following many times - http://www.mathpages.com/home/kmath528/kmath528.htm. If accelerating charges radiate would seem an open question. My understanding is it is not an open question if an accelerating mass radiates gravitational waves - GR predicts it does - or does it? Do others have any thoughts? Thanks Bill. Hi Bill. I was fortunate to attend a talk recently about uniformly acclerated charges. Also, I should mention many references about the topic are available in the slides from the talk: http://plasma4.sr.unh.edu/ng/uac-unh.pdf cheers - Thanks for the links - great stuff. Now for my two cents worth - I do not think a uniformly accelerated charge radiates because of the EEP. The usual explanation of why charges on earth do not radiate (a charge is an extended thing including the field which due to tidal forces is not the same as a uniformly accelerated charge) I do not agree with. Are you talking about because of gravitational acceleration? An object sitting on the surface of the earth is not accelerating downwards at 9.8m/s/s.. that force is balanced by frictional electric forces from the rock pushing up. Some more examples of accelerated charges radiating: a fluorescent light, a cell phone antenna, synchrotron, bremstrahlung.. Feynman and Wheeler demonstrated that fields are not required to formulate classical EM - thus the answer looks unreasonable - at least to me. I suspect the true resolution lies in QED. I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? That mechanism explains repulsive forces but not attractive. |
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#12
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shevek wrote:
I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. That mechanism explains repulsive forces but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Regards Ken S. Tucker |
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"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in message news:qRsZd.5192$uk7.4852@fed1read01... Dear Bill Hobba: "Bill Hobba" wrote in message ... "N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox wrote in message news:JTqZd.5164$uk7.3057@fed1read01... Dear Penelope: "Penelope" wrote in message ... On Mon, 14 Mar 2005 "Bill Hobba" wrote: I have given the following many times - URL:http://www.mathpages.com/home/kmath528/kmath528.htm If accelerating charges radiate would seem an open question. My understanding is it is not an open question if an accelerating mass . radiates gravitational waves - GR predicts it does - or does it? Do others have any thoughts? The question discussed on that web page is whether a UNIFORMLY accelerating charge radiates. General relativity does not predict that a uniformly accelerating mass radiates. In fact, there can't be any such thing as a simple uniformly accelerating mass... what would be causing it to accelerate? Sitting on the surface of a planet, a test body is being uniformly accelerated from its free-fall elliptical orbit. And electrostatic force is what is providing the acceleration. Does this qualify? AFAICS David it does not qualify. I should have seen it from the beginning as well. From the EEP if a uniformly accelerated mass radiated then we would, theoretically, have a free source of energy for particles at rest on earth. When viewed from a frame in free fall it would be acclerating so should radiate. Frame dragging. "Boosting" of photons (either red or blue shift) past a spinning object (which was only proposed, not observed). I think you may have too narrow an expectation of "radiation". And it wouldn't be "free energy", since conservation of momentum would require that-which-spins to spin a little more slowly. And I also see that I have the object spinning, which is not what you had stated. It obviously does not (or you would have a free source of energy) so unformily accelerated masses do not radiate grvitaitonal waves. Waves, perhaps not. Energy, I believe so. Note anomalous boosts of satellites (during slingshot maneuvers), and frame dragging. This is the same argument the mathpage link I gave about uniformly accelrated charges radiating used - 'One of the most familiar propositions of elementary classical electrodynamics is that "an accelerating charge radiates". In fact, the power (energy per time) of electromagnetic radiation emitted by a charged particle is often said to be strictly a function of the acceleration of that particle. However, if we accept the strong Equivalence Principle (i.e., the equivalence between gravity and acceleration), the simple idea that radiation is a function of acceleration becomes problematic, because in this context an object can be both stationary and accelerating. For example, a charged object at rest on the Earth's surface is stationary, and yet it's also subject to a (gravitational) acceleration of about 9.8 m/sec2. It seems safe to say (and it is evidently a matter of fact) that such an object does not radiate electromagnetic energy, at least from the point of view of co-stationary observers. If it did, we would have a perpetual source of free energy. Since the upward force holding the object in place at the Earth's surface does not act through any distance, the work done by this force is zero. Therefore, no energy is being put into the object, so if the object is radiating electromagnetic energy (and assuming the internal energy of the object remains constant) we have a violation of energy conservation.' Let me say this about that... ;) Co-stationary observers perceive a different charge than an observer that is free falling past the charge (say on the charge's geodesic without the support of the Earth). The difference in energy (not charge) would be the magnetic field created by this current. I'm probably wrong, but I don't see a conservation of energy problem. If we had access to the geodesic that any particular sacrificial mass would normally follow, yes we could get "free" energy... but we'd eventually fill the well. I'm ready for my trouncing. Remember the caveat - 'and assuming the internal energy of the object remains constant'. If you have a process how it could tap into that then you have an out. Also, as the mathpage link I gave explained, the issue is controversial. Thanks Bill David A. Smith |
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"Tom Roberts" wrote in message om... Bill Hobba wrote: My understanding is it is not an open question if an accelerating mass radiates gravitational waves - GR predicts it does - or does it? Do others have any thoughts? First you must define what you mean by "accelerating" -- in Minkowski spacetime an inertially-moving mass can appear to be "accelerating" if one describes its postion using non-inertial coordinates. As GR is coordinate independent, clearly one must not attempt to use such a coordinate-dependent meaning of "accelerate". So it seems the only useful meaning is: having a nonzero 4-acceleration. But a test particle orbiting a large mass has zero 4-acceleration, and yet we know that two large masses orbiting each other will definitely generate gravitational radiation. So zero 4-acceleration does not preclude gravitational radiation (insofar as 4-aceleration makes sense for a non-negligible mass object). Good point. A spherical shell pushed symmetrically by many rockets into its center could have non-zero 4-acceleration for each point of its surface, and yet no gravitational radiation can be emitted (due to the spherical symmetry -- Birkhof's theorem applies). So nonzero 4-acceleration does not ensure gravitational radiation. Conclusion: no simple but generally-valid statement can be made. Yep. Thanks Bill Tom Roberts |
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Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. That mechanism explains repulsive forces but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. |
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shevek wrote:
Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. Ok, but the field itself is physically caused by a relative relation of charges. Above I provided a GR solution for a charge couple "a" and "b". All the charges in the Earth and Moon are electro-magnetically coupled. Assuming neither is electrostatically charged then for every repelling couple there is an attractive couple. Do the arithmetric on that, it quite neat. Repelling Couples = Attractive Couples when gravitating bodies are neutral. Incidentally, gravitation results because attraction is slightly stronger than repulsion, between charges, that we call a gravitational field. The field doesn't really have an independent existance, it's a simplification of the force equation by setting the test particle to a unit mass (F =GMm/r^2 = GM/r^2 when m=1), likewise for EM-force. That mechanism explains repulsive forces but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. Set E(a) to the Electric field of "a" etc, GR provides this solution for a pair of naked charges "a" and "b", G_00 = E(a)*E(b)= T_00 On the LHS is the continuum, and on the RHS is the quantum field. ((BTW use g_00 = 1 - a*b/r^2, and Nabla^2(a/r)=0.)) Is that the resolution we care for. Thanks Shevek Ken S. Tucker |
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"Ken S. Tucker" wrote in message oups.com... shevek wrote: Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. Ok, but the field itself is physically caused by a relative relation of charges. Above I provided a GR solution for a charge couple "a" and "b". All the charges in the Earth and Moon are electro-magnetically coupled. Assuming neither is electrostatically charged then for every repelling couple there is an attractive couple. Do the arithmetric on that, it quite neat. Repelling Couples = Attractive Couples when gravitating bodies are neutral. Incidentally, gravitation results because attraction is slightly stronger than repulsion, between charges, that we call a gravitational field. The field doesn't really have an independent existance, it's a simplification of the force equation by setting the test particle to a unit mass (F =GMm/r^2 = GM/r^2 when m=1), likewise for EM-force. That is an interesting notion. Two plausible mechanisms come to mind that had never occured to me before. Either as a result of deformation or displacement, the attractive components could *effectively* have a path just slighly shorter than their repulsive partners. That's tooooo simple. But just offhand I can't offer argument. Maybe later LOL. Sue... That mechanism explains repulsive forces but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. Set E(a) to the Electric field of "a" etc, GR provides this solution for a pair of naked charges "a" and "b", G_00 = E(a)*E(b)= T_00 On the LHS is the continuum, and on the RHS is the quantum field. ((BTW use g_00 = 1 - a*b/r^2, and Nabla^2(a/r)=0.)) Is that the resolution we care for. Thanks Shevek Ken S. Tucker |
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#18
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jahn wrote:
"Ken S. Tucker" wrote in message oups.com... shevek wrote: Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. Ok, but the field itself is physically caused by a relative relation of charges. Above I provided a GR solution for a charge couple "a" and "b". All the charges in the Earth and Moon are electro-magnetically coupled. Assuming neither is electrostatically charged then for every repelling couple there is an attractive couple. Do the arithmetric on that, it quite neat. Repelling Couples = Attractive Couples when gravitating bodies are neutral. Incidentally, gravitation results because attraction is slightly stronger than repulsion, between charges, that we call a gravitational field. The field doesn't really have an independent existance, it's a simplification of the force equation by setting the test particle to a unit mass (F =GMm/r^2 = GM/r^2 when m=1), likewise for EM-force. That is an interesting notion. Two plausible mechanisms come to mind that had never occured to me before. Either as a result of deformation or displacement, the attractive components could *effectively* have a path just slighly shorter than their repulsive partners. That's tooooo simple. But just offhand I can't offer argument. Maybe later LOL. Sue... Well Sue, I think GR is inclined to agree with you. The simple formula is, S^2 = X^2 + a*b (1) where S=Signal distance, X is fixed, then, S^2 = X^2 - q^2 (when a=-b, Attractive) S^2 = X^2 + q^2 (when a=b, Repulsive). If you would like an explanation, I figure, it's because "repelling" charges store positive energy in the field they create but "attractive" store negative energy. Further analogy, it takes light "longer" to go threw air or water or glass, than a vacuum, each medium has positive energy. The thing about GR is one can use a dozen analogies and each is right, and Sue's deformation analogy is as good as any. I liken the way SR unified electrostatic forces and magnetism, to the way GR unifies electrostatics and gravitation. Back in the 70's I met with Ray Vanstone of the U of T about unification of EM and gravitation. He pointed out that it was done at least implicitly, by G_uv=T_uv, ((he used his own text BTW)). I haven't found an explicit solution, aside from the one below, (I call it unitivity because in classical GR charge is not a length). By unitizing charge to a be length, and an invariant one at that, we're able to use Eq.(1) sensibly. If you figure it out you'll find (I hope!), charge^2 = action and action = length^2 when you convert mass to length as GR allows. Because charge is invariant, it is orthogonal to spacetime, so in Eq.(1) the charges are orthogonal to X. (Recall lengths perpendicular to motion are invariant). The unitivity solution needs to be consistent with QT, and I've argued GR predicts QT recently with someone called "Non ame". That mechanism explains repulsive forc es but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. Set E(a) to the Electric field of "a" etc, GR provides this solution for a pair of naked charges "a" and "b", G_00 = E(a)*E(b)= T_00 On the LHS is the continuum, and on the RHS is the quantum field. ((BTW use g_00 = 1 - a*b/r^2, and Nabla^2(a/r)=0.)) Is that the resolution we care for. Thanks Shevek Ken S. Tucker Regards Ken S. Tucker |
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#19
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"Ken S. Tucker" wrote in message ups.com... jahn wrote: "Ken S. Tucker" wrote in message oups.com... shevek wrote: Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. Ok, but the field itself is physically caused by a relative relation of charges. Above I provided a GR solution for a charge couple "a" and "b". All the charges in the Earth and Moon are electro-magnetically coupled. Assuming neither is electrostatically charged then for every repelling couple there is an attractive couple. Do the arithmetric on that, it quite neat. Repelling Couples = Attractive Couples when gravitating bodies are neutral. Incidentally, gravitation results because attraction is slightly stronger than repulsion, between charges, that we call a gravitational field. The field doesn't really have an independent existance, it's a simplification of the force equation by setting the test particle to a unit mass (F =GMm/r^2 = GM/r^2 when m=1), likewise for EM-force. That is an interesting notion. Two plausible mechanisms come to mind that had never occured to me before. Either as a result of deformation or displacement, the attractive components could *effectively* have a path just slighly shorter than their repulsive partners. That's tooooo simple. But just offhand I can't offer argument. Maybe later LOL. Sue... Well Sue, I think GR is inclined to agree with you. The simple formula is, What? They must be offering a prize for GR salesperson of the month. It's a great technique tho' and I'll put a good word in for ya if Al's Used Car Lot calls for a reference. )S^2 = X^2 + a*b (1) where S=Signal distance, X is fixed, then, S^2 = X^2 - q^2 (when a=-b, Attractive) S^2 = X^2 + q^2 (when a=b, Repulsive). If you would like an explanation, I figure, it's because "repelling" charges store positive energy in the field they create but "attractive" store negative energy. Further analogy, it takes light "longer" to go threw air or water or glass, than a vacuum, each medium has positive energy. OK ... I'll add those to the list. The thing about GR is one can use a dozen analogies and each is right, and Sue's deformation analogy is as good as any. I liken the way SR unified electrostatic forces and magnetism, to the way GR unifies electrostatics and gravitation. Back in the 70's I met with Ray Vanstone of the U of T about unification of EM and gravitation. He pointed out that it was done at least implicitly, by G_uv=T_uv, ((he used his own text BTW)). I haven't found an explicit solution, aside from the one below, (I call it unitivity because in classical GR charge is not a length). Probably only because it is a bit harder to express. By unitizing charge to a be length, and an invariant one at that, we're able to use Eq.(1) sensibly. If you figure it out you'll find (I hope!), charge^2 = action and action = length^2 when you convert mass to length as GR allows. Because charge is invariant, it is orthogonal to spacetime, so in Eq.(1) the charges are orthogonal to X. (Recall lengths perpendicular to motion are invariant). OK ... I'll let ya get away with that since you have declared your clocks to be funny. LOL The unitivity solution needs to be consistent with QT, and I've argued GR predicts QT recently with someone called "Non ame". OK... I'll dump my tinker-toys out this weekend and see if we can include or exclude some of these mechanisms by some other means. Sue... That mechanism explains repulsive forc es but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. Set E(a) to the Electric field of "a" etc, GR provides this solution for a pair of naked charges "a" and "b", G_00 = E(a)*E(b)= T_00 On the LHS is the continuum, and on the RHS is the quantum field. ((BTW use g_00 = 1 - a*b/r^2, and Nabla^2(a/r)=0.)) Is that the resolution we care for. Thanks Shevek Ken S. Tucker Regards Ken S. Tucker |
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jahn wrote: "Ken S. Tucker" wrote in message ups.com... jahn wrote: "Ken S. Tucker" wrote in message oups.com... shevek wrote: Ken S. Tucker wrote: shevek wrote: I disagree. Do you mean there is no field, because the force is carried by an exchange of mesons (in this case photons)? First, one can argue that there still is a field - just defined as the force on a particle divided by the charge. Second, how is a proton attracted to an antiproton by a photon exchange? From the perspective of GR the Energy Density, is the product of two E-fields from charges "a" and "b" i.e., T_00 = E(a)*E(b) T_00 = - E^2 ,(attractive a=-b) T_00 = + E^2 ,(repulsive a= +b) These in turn set-up the G_00, (G_uv=T_uv) and the resulting g_uv and from them the geodesics. Energy and therefore Energy Density varies dis- continuosly, hence the E-fields (E^2 above) also vary discontinuously, that would be by photons emitted by the pairing of protons and anti-protons. Which direction are the photons emitted - if they are to be "exchanged", then the photons are emitted toward the other particle.. in which case the force is repulsive. If the (virtual) photons are emitted away from the opposite particle, than what force caused them to be emitted? We are back to a field again. Ok, but the field itself is physically caused by a relative relation of charges. Above I provided a GR solution for a charge couple "a" and "b". All the charges in the Earth and Moon are electro-magnetically coupled. Assuming neither is electrostatically charged then for every repelling couple there is an attractive couple. Do the arithmetric on that, it quite neat. Repelling Couples = Attractive Couples when gravitating bodies are neutral. Incidentally, gravitation results because attraction is slightly stronger than repulsion, between charges, that we call a gravitational field. The field doesn't really have an independent existance, it's a simplification of the force equation by setting the test particle to a unit mass (F =GMm/r^2 = GM/r^2 when m=1), likewise for EM-force. That is an interesting notion. Two plausible mechanisms come to mind that had never occured to me before. Either as a result of deformation or displacement, the attractive components could *effectively* have a path just slighly shorter than their repulsive partners. That's tooooo simple. But just offhand I can't offer argument. Maybe later LOL. Sue... Well Sue, I think GR is inclined to agree with you. The simple formula is, What? They must be offering a prize for GR salesperson of the month. It's a great technique tho' and I'll put a good word in for ya if Al's Used Car Lot calls for a reference. )LOL, classical Grist's have dumped me, I couldn't get g-waves for LIGO or gravitomagnetism for GP-b. S^2 = X^2 + a*b (1) where S=Signal distance, X is fixed, then, S^2 = X^2 - q^2 (when a=-b, Attractive) S^2 = X^2 + q^2 (when a=b, Repulsive). If you would like an explanation, I figure, it's because "repelling" charges store positive energy in the field they create but "attractive" store negative energy. Further analogy, it takes light "longer" to go threw air or water or glass, than a vacuum, each medium has positive energy. OK ... I'll add those to the list. The thing about GR is one can use a dozen analogies and each is right, and Sue's deformation analogy is as good as any. I liken the way SR unified electrostatic forces and magnetism, to the way GR unifies electrostatics and gravitation. Back in the 70's I met with Ray Vanstone of the U of T about unification of EM and gravitation. He pointed out that it was done at least implicitly, by G_uv=T_uv, ((he used his own text BTW)). I haven't found an explicit solution, aside from the one below, (I call it unitivity because in classical GR charge is not a length). Probably only because it is a bit harder to express. By unitizing charge to a be length, and an invariant one at that, we're able to use Eq.(1) sensibly. If you figure it out you'll find (I hope!), charge^2 = action and action = length^2 when you convert mass to length as GR allows. Because charge is invariant, it is orthogonal to spacetime, so in Eq.(1) the charges are orthogonal to X. (Recall lengths perpendicular to motion are invariant). OK ... I'll let ya get away with that since you have declared your clocks to be funny. LOL The unitivity solution needs to be consistent with QT, and I've argued GR predicts QT recently with someone called "Non ame". OK... I'll dump my tinker-toys out this weekend and see if we can include or exclude some of these mechanisms by some other means. Sue... Ken That mechanism explains repulsive forc es but not attractive. Virtual photon exchange is a conceptualiztion of mathematics. If you want you are entitled to think in terms of the annilihation of virtual antiphotons and photons, to create the -E^2 above, and by doing so emit a photon. I wouldn't argue with that. Thanks Ken, well that's an idea.. I don't know QED actually, so I was looking for a definitive answer. All the quantum field theorists I talk to give a different answer - one popular one is that the virtual photon being exchanged has a momentum facing the other way from it's wavevector! Which doesn't make sense to me. Anyway, a photon is it's own antiparticle - and photons move through each other without effect in a linear medium. Set E(a) to the Electric field of "a" etc, GR provides this solution for a pair of naked charges "a" and "b", G_00 = E(a)*E(b)= T_00 On the LHS is the continuum, and on the RHS is the quantum field. ((BTW use g_00 = 1 - a*b/r^2, and Nabla^2(a/r)=0.)) Is that the resolution we care for. Thanks Shevek Ken S. Tucker Regards Ken S. Tucker |
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