Bremsstrahlung vs Relativity

Discussion in 'Physics & Math' started by MacM, Jan 2, 2006.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I do not like the "some times they do / some times they don't" escape hatch here any more than I liked the same applied to Newton's 3d law.

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    The orbiting electron, if the BSC theory of superconductivity is still basically valid (and I bet it is, but 30+ years have passed since I knew it) then the "coupled pair of electrons" can not get far apart, (It think). - a few centimeters at most and the superconducing loop could be much bigger, but your point that a normal conductor with DC curent does not radiate is killer of even these QM ideas regardless of the separations.

    I am begining to think that, acelerating electrons NEVER radiate, just because they are accelerating, but if they are part of a current and that curent changes (because the speed changes = acceleration),then Maxwell's equation for the CHANGING CURRENT, makes dB/dt non zero so there is a dE/dt i.e. radiation.

    For example, if you have a string of electrons going around in a SECTION ONLY of circular accelerator, even at constant speed, yes there is radiation; but now suppose the accelerator has a equal length of equal number of electrons going at equal speed around the other way, also producing the same radiation. Then, I predict that as they pass there is no radiation from the space they share in common, or at least the central section of that shared space where for some time the net current in that shared section is a STEADY zero.

    Note the radial acceleration of both bunches of electrons has not changed, but acceleration, itself is NOT the direct cause of radiation. It usually is a cause of a changing current and that is the true direct cause of the radiation. This works for both the superconducting and the normal conducting DC current.

    The x-ray tube works, not directly becuse a bunch of electrons, which fell thru kilovolts and were giong very fast had great de-acceleration as the slam into the tungesten target. You have, however, by this produced a near "step function" in time of the current, which when fourrier transformed from the time domain to the frequenct domain is rich in very short wavelengths, we call X-rays.

    (Also, but I do not want to mention it much, the impack energy may be enough to knock out of orbit an inner shell electron and when a more outer shell one falls into its place, you get spectral line X-rays. So target matterial maters also, but the X-rays I spoke of from the step function of the current are "continum radiation" or "bremsstrhlung", not line radiation.)

    I am reasonably sure I have the answer now.
     
    Last edited by a moderator: Jan 23, 2006
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  3. DaleSpam TANSTAAFL Registered Senior Member

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    Well, I certainly understand that. In this case, however, I think that it is an indication that Bremsstrahlung is not a fundamental law like Newton's 3rd. I don't even think it is even a definitional "law" like Ohm's law that is basically a definition of resistance.

    I think that sounds reasonable. I have always had a hard time figuring out what the current should be for a single charged particle flying around in free space. But I am sure someone has a workable definition that would fit in well with your suggestion and probably accurately predict Bremsstrahlung for both circuits (like Dipole antennae) and free charges.

    -Dale
     
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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I was not trying to declare it a "law" - only indicate that physics of aceleration effect is not "maybe this today, maybe that tomorow." (althouhg our knowledge of it can be.) Even what we do call "laws" are really just convenient generalizations of a lot of completely consistent physics.

    Nature has no courts or lawyers. No laws. But it does seem to be describable in a relatively few man-invented generalizations. Parts of nature can not be deterministically predicted, even with these generations (exceptic statistically) and that too is consistently true, every day, in every case. I.e.

    I reject the existence of genuine "miracles."

    By our exchange, I have learned that acelerated charges do usually imply a changing current (but not in the example I invented) and a changing current ALWAYS radiates, but that when the accelerted charges do not cause a changing current, there is no radiation, so aceleration of charge, by itself (no changing current), NEVER radiates.
     
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