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Maxwells theory of electro-magnetic radiation: |
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| Jul28-04, 05:37 AM | #1 |
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Maxwells theory of electro-magnetic radiation:
Maxwells theory of electromagnetic radiation has been around for the past two hundred odd years. Although it is probably one of the most elegant and aesthetic theories ever to be introduced in the study of Physics , today it is an anachronistic and misleading theory , based for the most part on faulty logic and observation. It accurately reflects the age in which it was conceived and is reminiscent of an eighteenth century steam engine more than anything else , Maxwell envisions electromagnetic radiation as huffing and puffing its way across the vast reaches of space. The whole conception of electric and magnetic fields alternatively exchanging energy and thereby sustaining themselves is at heart erroneous for the simple reason that there are no electric and magnetic fields per se , there are only electromagnetic fields. To speak of an electric field is wrong , there are no electric fields The field in and around a charged capacitor is frequently referred to as an electric field , in fact if a definition of an electric field exists it might be said to be represented by the field associated with a charged capacitor , yet this field is definitely not an electric field it is an electromagnetic field . How then can Maxwell’s theory possibly make sense or continue to possess any validity. Even particle physicists speak blandly of results obtained under the influence of a strong magnetic field when what they actually mean is a strong electromagnetic field. The premise that electric and magnetic fields have an independent existence has fragmented the whole of physics to such an extent that it is difficult to envision ever replacing these concepts even if our whole understanding of physical phenomenon depends on such changes being made.
Consider also this notion of spinning electrons , where has this come from. So OK the atomic model was originally based on the planetary model , it is common knowledge that the earth spins , ergo the electron must also spin ! If this is indeed the reason for the spin of a particle gaining such wide-spread acceptance , then consider this , the moon does not spin ! Consider again the magical aspects of the photon , it is both a particle and a wave , it can be in two places simultaneously , it always travels at the speed of light ( in a vacuum ) it can never be found at rest , except in its virtual form when present in electromagnetic fields surrounding a conductor in which a current is flowing , why it is at rest or attached to the conductor in this instance and not in others has never been explained or is explained by the fact that in this situation photons are virtual . In short the photon stands for everything that we never see in real life. Yet things that we do see in real life are sometimes things which resemble the symbiosis of a wave and a particle , why can’t the photon be one of these ? Things have reached such a pass that it is impossible to even mention such a thought , let alone the idea ,that a photon might in fact actually be something that resembles a wave and a particle , such as a very high frequency wave . Apparently it is not possible , it has to be both a wave and a particle depending upon how it is viewed. With such intransigence on the part of modern day physicists in even considering possibilities to explain the seeming contradiction in a photon , it must inevitably follow that change is almost impossible. |
| Jul28-04, 10:37 PM | #2 |
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Normally I'd grill a post like this, but that's getting old. Let's try some reason and see what happens
As for virtual photons, they are the result of our using Feynman's techniques for QED. They have no physical existence. Even if they do, your example is one of the most awful uses of QED I've ever seen. I assume you just picked it up somewhere, please let it go, it is an incorrect picture. a) "I believe there's a huge conspiracy amongst scientists to cover up the fact that all our theories are crap" b) "I don't like our current theories because they contradict my 'common sense' preconceptions, and I don't understand the level to which they have been tested or how hard it was to make the paradigm shift to them" c) "I have my own pet theory that I think is better than everything those physics bigots have but those physics bigots will never accept it because they're bigots and intransigents and they want the glory for themselves" ... you need to let go of that view right now, throw away whatever you've been reading if you picked it up somewhere, and learn what physics is all about. I will be glad to recommend books on the topics you seem to lack understanding of. If on the other hand you have already made up your mind about the mainstream theories and are absolutely determined to become a crackpot or crank, well I can't stop you. I'll be around. |
| Jul28-04, 10:54 PM | #3 |
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When my car 'burps' I tweak it, not run it off a cliff and buy a new one.
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| Jul31-04, 11:08 AM | #4 |
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Maxwells theory of electro-magnetic radiation:
In reply to Anti-crank
Actually Maxwell's theory remains as elegant and useful today as it was then, especially when written in four-vector form. It survived both special relativity and quantum mechanics. It was only superseded by Quantum Electrodynamics, which predicts deviations from eg the Coulomb potential. If we accept the fact that Maxwell’s theory is correct , how would this account for the existence of photons as individual ‘packets ‘ of energy? Maxwell’s theory of electromagnetic radiation is essentially a wave theory which works in the broader sense but fails in the more specific sense. In the photoelectric effect Maxwell's wave theory predicts that as the intensity of light is increased, the current flow should also increase. The frequency should not affect the maximum kinetic energy of the photoelectrons. In reality the intensity of the light has nothing to do with photo-electric emission and it is only the frequency of the incident light which has any effect. Maxwell confirmed that electromagnetic waves are generated by accelerating electric charges. Consequently, there developed a theory for the emission of light as being due to the oscillatory motion of electric charges located in the atoms of the radiating source. Today we know that in fact the emission of light is due to electrons gaining and losing energy and not as was thought due to their rotation around the nucleus. This particular point is a good illustration of the reasoning I have been trying to follow. While it is admitted that light is emitted by electrons changing their energy levels , electromagnetic radiation of lower frequency such as radio-waves is still attributed to the oscillatory motion of ions and electrons in the crystal lattice of the conductor. So what we have in effect is two causative factors for what is essentially the same phenomenon , electromagnetic radiation. The point is that even gamma rays (another form of electromagnetic radiation ) are created through a similar process , namely through the nucleus losing or gaining energy . For instance it would be ridiculous to suggest that gamma rays are produced through the oscillatory motion of nucleons . The next thing is , how is electrical energy conducted through an electrical conductor ? The widely accepted notion is that it is through electrons , but electrons only interact through photons , yet photons are prohibited from the electrical conduction process by the Pauli Exclusion Principle. The only answer left is that electrical energy must be transmitted through “virtual” photons , which is ridiculous. This is precisely the point I am trying to make. If we accept Maxwell’s theory of a displacement current , it means that electromagnetic forces (i.e fields ) are excluded from the process of the conduction of electrical energy. In reality electrical energy , (look at transformers ) must be conducted through electromagnetic forces . In turn electromagnetic forces must be mediated by photons . However because Maxwell’s theory needs a displacement current in order to work it specifically prohibits this. Light ( a form of electromagnetic radiation ) travels through solids from atom to atom and electron to electron , why can’t the same process apply to lower frequency electromagnetic radiation (i.e top a current flowing in a conductor ) ? The spin of electrons, photons, whatever, is intrinsically determined by the relativistic wave equation of the free particle - Klein-Gordon for spin-0, Dirac for spin-1/2, and Proca for spin 1. The particles satisfying Dirac or Proca equations can be shown to carry a form of intrinsic angular momentum since the angular momentum operator does not commute with the free particle Hamiltonian Accepted , but the notion of spin was first instituted by Henri Lorentz , who keeping in mind Maxwell’s theory and the negative charge of the electron felt that there had to be an additional motion of the electron to account for the magnetic properties , which he had suggested might be due to its spin. This theory was revived by Dirac and others. Nothing magical about it. Counterintuitive, perhaps, but our theories can accomodate it nicely. The universe is under no obligation to live up to our expectations. QM deals with the "particle and wave" aspect and SR deals with the "always travelling at c" aspect. All these properties of the photon and other sub-atomic particles as manifested in the “Double Slit Experiment “ would be perfectly accounted for by an aether type of scenario. Before scoffing at this statement , you should realize that QM itself has put forward a theory of an aether of sorts. Without this aether theory of QM there would be no way for QED to work. |
| Aug1-04, 12:54 AM | #5 |
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My deepest apologies. I had written two pages worth of reply but the godforsaken site ate it - I was logged out (timeout?) before I got a chance to post and it vanished at the compose screen. I do not have the mental strength to rewrite it now. **slams keyboard**
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| Aug1-04, 07:16 PM | #6 |
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Just two points regarding this most serious and documented post:
Why the notion of spin was so determined by a newtonian mechanics concept, such as those, they are normally used to describe it? Is it not that notion of spin an entirely electromagnetic notion? In fact the electron has an intrinsic "magnetic" field or, as it were, an intrinsic magnetic property, why should we try then to explain something that is intrinsic, within the concepts of another old paradigm? Just some inquisite thoughts Regards EP |
| Aug2-04, 02:53 AM | #7 |
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As for transformers, what does the displacement current term have anything to do with them? I challenge you to mathematically show that the displacement current makes them not work. I think they were around even before Maxwell wrote his equations. They're all about EM induction, which is nicely explained by Maxwell - and hence low energy QED. EM fields are present in the transformers, yes, but it is the action of those fields on the electrons in the wires that makes the transformer do its job. Hence virtual photons (if you want to think of it this way, but I will not defend that model too far) are present - they carry information between the driving AC voltage in the primary coil to the electrons in that coil, from the electrons in the primary to the electrons in the secondary, and from the electrons in the secondary to whatever device it is attached to. On the other hand, the displacement current is absolutely required for the consistency of the framework and for the existence of (classical) EM waves. As for scoffing, I have done that in the past (just see my very first post), and I will do so again, whenever someone takes it upon himself to single-handedly rewrite physics, or some large portion of it. (I am not implying you are trying anything of the sort.) In every such instance that I am aware of, such people exhibit either huge gaps in their understanding of the physics they're trying to rewrite, are unaware of the enormity of their task, and/or are unable to put their speculations into a rigorous formalism. Worse still, they tend to show cognitive dissonance when the flaws in their ideas are pointed out, paranoia and/or delusions of grandeur, prejudice against the physics community, or even up to all of the above. Why uneducated (scientifically speaking, of course) people think they are capable of judging existing theories wrong or writing their own theories is utterly beyond me. I don't claim to know how to design and build a house, and if an architect does the job for me, I defer to his judgement. That may seem elitist to some, but I believe otherwise. Would you allow just anyone to perform brain surgery on you? Of course not, it’s a task that requires a great deal of training and experience. Science works the same way, and frankly I am sick of the indignity it has to suffer from cranks and crackpots. No other highly skilled profession has to endure it. When's the last time you've heard some sixteen year-old claiming they can perform brain surgery? Yet here we have sixteen year-olds obstinately pushing a model of gravity so flawed it's not even worthy of my attention. Personally I blame it on the equally unexplainable anti-intellectuallism in popular culture, but I do have to give it one shred of credit: its existence, and what has come forth from it, is the main reason I live and breathe today. Virtually, of course. |
| Aug2-04, 08:28 AM | #8 |
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This can be explained via QFT, or by the 'old' QM where EM waves are given ad hoc particle properties. I don’t claim that Maxwell's model explains the photoelectric effect, but that the Schroedinger or Dirac equations can incorporate interactions with a classical electromagnetic field described by the potentials V and A. In fact, the first-order approximation to QED amounts - as far as interactions between charges are concerned - to classical electromagnetism, as well as the required particle properties for photons. Because it’s a rather rigorous proof, it’s a little long to state here, but I’ll make use of this later on.
Some of the drawbacks of Quantum Field Theory: The Quantum Mechanics theory for the propagation of electromagnetic radiation is represented by Quantum Field Theory . Quantum Field Theory describes processes in which particles are created or destroyed. Put simply this means that the energy of the photon is transmitted through the creation and annihilation of virtual particles. When a quantum field becomes more excited , the number of quanta of excitation increases. This occurs because new particle-anti particle pairs are created from radiation. When a quantum field becomes less excited the number of quanta of excitation decreases. This is achieved by processes in which particles and anti-particles collide and annihilate one another to produce radiation. (Both of these processes are permitted by Einstein’s E = mc2 and were explicitly predicted by Dirac . However the equation E = mc2 Does not suggest that these interactions can take place at the low energies present in an electromagnetic field , which can typically be as low as 10 –19 eV , according to Einstein’s theory the minimum energy for transformations to take place should be at least 1.5 MeV.] These were attractive features of quantum field theory and raised the hope that it might be truly a fundamental theory capable of providing a new world view. However there were serious problems within quantum electrodynamics that had to be overcome before such hopes stood any chance of being realized. Using QED to predict the value of a physically measurable quantity involved , in practice , working out the contribution made by several different sub-processes . Put in other words how does the translation of a specific energy evolve through interaction via the creation and annihilation of virtual particles . Making sure that these sub-processes were fully identified was a problem in itself , working out their individual contributions was even worse. Even in the simplest cases determining the contribution was difficult , and in the more complicated cases the result was usually a meaningless infinity showing that something was wrong. Put simply Quantum Field Theory does not work , it attempts to juxtapose the alternating electric and magnetic fields of Maxwell’s theory with the creation and annihilation of virtual particle pairs. The question of how theory electromagnetic waves propagate is still open to question. I have to pick on this one. This statement is so ignorant of elementary quantum mechanics that I must insist you rectify that before we debate QM any further. Photons are bosons, and do not obey the EP. As for QM's model of conduction, this is more indepth; if you're willing to make an effort to learn it, I'm willing to help along the way. I am sorry you are wrong , I cannot at the moment post the mathematical proof , but I have it here somewhere. Free electrons , such as those found in counductors , according to the EP cannot absorb or emit photons becuase they can't cope with the recoil. It is in every elementary text book. I will post a longer reply later dealing with the other points. |
| Aug3-04, 01:24 AM | #9 |
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| Aug4-04, 06:35 PM | #10 |
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I am learning from this thread and think maybe you could help me with a related question.
Do you know of any experiment done in ultrahigh vacuum that has shown that any wavelength of light (as a beam or a single photon) has been deflected or changed in any way by a simple or complex, pulsing or static, electric field, magnetic field or an EM field? |
| Aug5-04, 02:56 AM | #11 |
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This is just plain wrong. Either this honestly is the picture you get from QED (in which case, do yourself a favor and study it properly; this isn't the only such 'pearl' you've let slip), or you are deliberately setting up strawmen to attack what those in the business call "the best theory we have". If you're unwilling to debate it on its own merits, then there's really no point for this discussion.
It took two thousand years for Ptolemy’s ideas to be discarded , it took much longer than that for Newton’s idea that objects will move indefinitely in a straight line unless subjected to some outside force to be enunciated ,and so on. I stress this point in order to demonstrate that merely the fact of an idea having been accepted for the past twenty or thirty years does not mean that it is true. Any opposition or change to accepted ideas , especially in science , has always resulted in fanatical opposition. QM itself was for a long time , subject to this kind of opposition , going back a little further in time , people were burnt at the stake if they so much as suggested that the earth might revolve around the sun or even that the earth was round ! In today’s enlightened scientific environment the least one can expect is , if not acceptance , then a certain amount of tolerance. In this respect PHYSICS FORUMS stands out almost alone on the web , in allowing people to air their views , regardless of how outrageous , in the theory forum. It is not always easy to explain such an abstract theory as QM in layman’s terms , or to convince someone with different ideas , given these limitations , of the validity of one’s own ideas. The option always exists , however , if one is interested enough , of looking into new ideas and trying to judge if they possess any foundation. In Quantum Field Theory more importance is given to fields than to matter , fields are all pervasive in the Universe while matter is merely a consequence of the interaction of fields . We are able to view matter as particles because fields tend to interact powerfully over infinitesimal areas. Hence , according to QFT , every field is associated with a particle and conversely every particle is associated with a field. Thus we have the electric field associated with electrons , the magnetic field associated with magnetons , the electromagnetic field associated with photons , the sound field associated with phonons , the gravitational field associated with the graviton and the list goes on through the strong force and the weak force and various other forces. Hence according to Quantum Field Theory matter is only a manifestation of the interaction of fields. The three main ideas underlying this theory are (1) sub-atomic particles have no independent existence (2) sub-atomic particles display characteristics of wave-particle duality (3) sub-atomic particles are/maybe manifestations of interacting fields. My own take on all this , is that QM is unequalled in explaining the working of the atom and interactions of the nucleus. When it comes to macroscopic phenomenon , and this is just my view , QM has gone catastrophically astray in accepting wave-particle duality as a fundamental axiom . I have posted this site in another thread , you might be interested in looking through it: http://www.geocities.com/natureoflight/pgindex |
| Aug7-04, 10:20 PM | #12 |
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| Aug7-04, 11:00 PM | #13 |
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Chapter 19, NonLinear Optics. There is a wealth of interactions using electromagnetics to control light. That is the chapter that shows how to construct a conjugate mirror which reflects light back directly the way it came in instead of at right angles. Interesting stuff !! Keep on chuggin !! Vern |
| Aug8-04, 01:10 AM | #14 |
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Interesting discussion. Points scored on both sides by my reckoning. I tend to lean towards the standing wave concept [matter is 'frozen' energy]. It makes sense. It would, however, help if someone could explain the process.
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| Aug8-04, 04:39 AM | #15 |
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Chronos
matter is 'frozen' energy Absolutely , I subscribe to this view. The point is how much energy is required to demostrate matter energy equivalence ? Surely not the energy present in radio waves as is implied in QM , even if these interactions are virtual ? Virtual interactions by their very classification should not impinge on the real world , even mathematically. Visit my site at http://www.geocities.com/natureoflight/pgindex |
| Aug8-04, 05:40 AM | #16 |
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Question: Since the known universe is presumed to be a mere 10.8E+24 meters in diameter, hence, longest EM wavelength possible, it should be easy to convert that to a temperature [you do the rest of the math, I am feeling lazy]. Will discuss what that may or may not mean after you integrate that over the upper limit imposed by the planck length.
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| Aug8-04, 07:10 AM | #17 |
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My point is then don't we really have a problem with the way we have coped those two different problems, I mean the symbolism we use? Must we not solve this another form of the wave-particle problem? I know there has been invented some "theoretical mechanisms" to solve the problem of symmetry breaking we find in nature, but then I wonder again don't we have a problem with the symbolism that must include both kinds of parities? not precisely with the nature of electrons and photons that are again manifestation of energy at basic levels, at those basic levels where we find ourselves with the need to rationalize duality in a concept of unit? But this rationalization of duality at atomic levels is certainly an open problem yet, if we want to solve this another schism we find in those two schools: that of QM and that of QED at least found in text books. Just some thoughts and questioning Regards EP |
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