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On The Nature Of Light

  1. Jul 19, 2003 #1
    [SOLVED] On The Nature Of Light

    The decision to define a photon as a sub-atomic particle is a difficult one to understand. According to the existing theory there is a different photon for every frequency in the whole of the electro-magnetic spectrum and for every possible combination of these frequencies. This quite substantial number of combinations can be compared to every possible sound or combination of sounds in the audible frequency that the human ear can discern . So in this way it might be deduced that light is not much different than sound. The problem is complicated by the fact that during the time when many of the theories on the nature of light were being formulated there was not enough information available about the manner in which light originated. While it was perfectly possible to understand the process by which sound originated , the origin of light was more obscure. Light seemed to possess the properties of being both a particle and a wave , as a result the approach to explaining light has been along completely different lines to those used to explain the phenomenon of sound. It could be said that when trying to explain the phenomenon of light physicists have put the cart before the horse. When explaining the phenomenon of sound they were able to see that a sound originated at some point , as for instance in the plucking of a taut string or wire and could be heard elsewhere . To explain the phenomenon of light , however , they had to start with the effects and then work back to the origin which is why there has been so much ambiguity in trying to explain what exactly light is. If sound can be taken to be the result of vibrations set up in the air , the phenomenon of light and electromagnetic radiation can simply be taken as being waves of a certain frequency contained in closed loops of electro-magnetic fields , if these loops of energy are short enough they would demonstrate the properties of a particle and also of a wave. Sound waves posses energy there is no reason to suggest that light frequencies (photons) do not.
    Maxwell's equations represent one of the most elegant and concise ways to state the fundamentals of electricity and magnetism. From them one can develop most of the working relationships in the field. There are however naturally certain premises on which Maxwell based his theories which are no longer valid :-

    1) For instance Maxwell believed that the movement of an oscillating current in a wire (antenna) gave rise to independent loops of external electrostatic and magnetic fields which sustained each other and acted on point charges in the direction in which the wave was propagating. We know from observation and experiment that this is not in fact true , and that it is the excitation of the electrons present in the wire that causes them to emit photons (any frequency in the whole of the electromagnetic spectrum is considered to be a photon ) , and that these photons consist of certain frequencies depending on the level of excitation. Given this fact it is reasonable to assume that the electromagnetic fields which are observed originate not from any external source but from the extremely large number of photons which excitation of the electrons in the wire gives rise to and that each such photon has its own electromagnetic field . In other words in Maxwell’s theory it seems that the effect has been taken for the cause.
    2) In all other respects Maxwell’s observation of how the electric and magnetic fields sustain each other holds good, since he based his premises on the fact that the electromagnetic field was built up around a central charge , except that it is reasonable to assume that the electromagnetic field is associated with the photon and not the other way around.

    The term photon as I have pointed out before is mis-leading and can be replaced for the purposes of this discussion with words like ‘contained’ frequency or energy. Maxwell’s equations in effect deal with how electric and magnetic fields are built up around a central force of energy. The origin of this energy it is here maintained lies not in the electric current in the wire but in the photons which are emitted by electrons in the wire due to excitation. In other words the fields are built up due to the energy of the photon .
    If we examine the manner in which a photon is emitted by an electron under excitation , this becomes more clear. For the purpose of this discussion it must be assumed that the electron is for all purposes a spherical conductor. Therefore any charge that it contains would be assumed to lie at its centre. When an electron is emitted , the electromagnetic field would therefore be set up tangentially to the surface of the conducting sphere (electron) while the direction taken by the photon ( energy , frequency ) would be straight out from the surface of the electron in a direct line with the centre. i.e the direction of the electron would be radially oriented to the electron. When two electrically charged objects rapidly reverse their polarities in a process known as oscillation , the result is without exception the propagation of electro-magnetic waves. When a photon is emitted by an electron this is exactly the situation that exists , the electron , when stimulated or excited ,takes on extra energy and becomes negatively charged (i.e has excess energy ) it gets rid of this extra energy by emitting a photon (Frequency , energy) . The electron is now positive with respect to the emitted photon and by a process of repulsion the photon is set free of the electron’s influence. This results in the electric and magnetic fields around the photon (frequency , energy) forming a closed loop. Thus the emission of a photon by an electron can be compared by analogy to Hertz’s spark experiment which first proved the existence of electromagnetic radiation , and can be thought of as having an exactly similar effect.
    The situation when a photon is emitted is therefore as follows . We have a central energy or frequency (the photon ) moving in the direction of propagation and at right angles to it we have its electro-magnetic field. This is a self sustaining system , the electric and magnetic fields sustain each other. This is the only way to account for the massive distances traveled by light and other electromagnetic radiation. In this depiction of the photon , we can view each photon almost as a nano-machine which has at its core a central frequency or energy and which is sustained by electric and magnetic fields which are self sustaining because they are constantly renewing each other. It is now possible to understand how light can have the properties of both a particle and a wave , the central energy or frequency behaves like a particle while its associated electro-magnetic field functions like a wave.
    How does light move at a constant speed ? Maxwell , during the formulation of his theory , was constantly looking for a force like the ether , to fully round out his equations , he never found it. But suppose there does exist a force similar to the ether which pervades the whole Universe . Such a force might in fact exist and if it does exit (the extremely small frequency and energy of the wave would make it difficult to detect ) its source might lie in the mediation processes of the atom. The electrons in an atom are continually emitting and reabsorbing ‘virtual’ photons . Such an action suggests a reversal of polarities (i.e first the ‘virtual’ photon is negative with respect to the electron and then it is positive , hence its emission and re-absorption be the electron). As has been pointed out before when two electrically charged objects rapidly reverse their polarities in a process known as oscillation , the result is without exception the propagation of electro-magnetic waves. It is possible that the process of electron/photon mediation gives rise to a weak electro-magnetic radiation of a wave length of about 10 x –20 m. and that this radiation since it originates in matter pervades the whole Universe. This would immediately explain the speed of light. It would be something like completing a circuit , the current would instantly be the same throughout the circuit.
     
  2. jcsd
  3. Aug 20, 2003 #2
    Very interesting subject. This point makes lightning more logical.
     
  4. Aug 20, 2003 #3
    What you're saying about EM-Waves, that it can only be generated electrons "dropping" from an excited state, is false. If you do a spectral analysis of hydrogen or any other atoms you will find that it absorbs and emits photons only at certain, well defined, energies. If your statement were true, you would have one hell of a hard time squeezing arbitrary radio-frequencies out of a copper antenna. :)
     
  5. Aug 20, 2003 #4

    Neo

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    Interesting article. Especially the part on causality vs. reverse causality with respect to sound and light. You could do it with artificial light, like a flashlight, for example, but it's difficult to think about a concrete, natural example. I suppose the Christian audience will say God was that First Cause of light in saying "Let there be light." I have an entirely different hypothesis, however. I believe that light was once only a wave - when it was only potential.
     
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