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Mass increase

  1. Nov 7, 2011 #1
    is there a physical explanation of mass increase ouside relativity?
    I understand it is KE, can it be explained with a progressive increase of "internal" resistance?
    I mean: if a body free-falls in the atmosphere external resistance increases with velocity, until it reaches terminal velocity vt, is it possible to consider C as a vt for particles? Thanks
  2. jcsd
  3. Nov 7, 2011 #2
    It is nothing like friction, but more like self induction. In fact, the increase of inertia with speed was known before the inception of relativity theory, and it was explained from electromagnetic theory.
    However, that only seems to work (somewhat) for the electron - the kinetic energy is stored in the magnetic field, and an infinite amount of energy is required to reach c. As far as I know, no theory has been established that accounts for the increase of inertia of neutral particles and atoms in a satisfying way.
  4. Nov 7, 2011 #3
    Thanks, harrylin, I did not mean friction, I said internal resistance, I was thinking of "production of magnetic energy" is it any different from what you say self induction?
    I see that the formula is the same as time dilation γv, is it causal or is there a deeper relation?
  5. Nov 7, 2011 #4
    You wrote "external resistance", and resistance implies friction. :wink: Anyway, indeed self induction has to do with magnetic field energy and for the electron there is an undeniable relationship. As a matter of fact, I once thought that they were unrelated and so I double-counted the effect - which is wrong. There is not an effect from "relativity" plus on top of that another one from self induction. But time dilation is not γv, where did you see that?
  6. Nov 7, 2011 #5
    "external" referred to air resistance, of course.
    if I got it right relativity did not explain it, only defined the curve of its values?
    if in γ we call β = x (cos θ) is the value of MI = sec θ?
    I was told in a forum that length-contraction LC and time-dilation TD curves are hyperbolic, is it true? how is TD related to MI? why formula is the same?

    do you know when was MI first theorized and when really detected?
    Thanks for your help
  7. Nov 7, 2011 #6
    That's correct: the explanations of relativity don't go deeper than describing ("predicting") what will be measured.
    I suppose that you mean with "MI" mass increase. But sorry, I don't understand your notations "x (cos θ)" and "sec θ".

    In the late 19th century, mass increase was described by Abraham (maybe the first?) and many others such as Lorentz. It was first "detected" (with some theoretical assumptions) by such people as Kaufman, you can "google" those names for more info.
    And there is a direct link between MI and TD, as in such experiments the trajectory depends on the dynamic mass: "heavier" electrons with higher energy are also "slower" to deflect.

    It may interest you that later experiments such as by Bertozzi,
    more clearly demonstrated that while the speed hardly increases, the kinetic energy still continues to increase.

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