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How big is an electron?

  1. Aug 27, 2004 #1
    Electrons are usually considered to be point-like particles but are there any
    theories that say they have a non-zero radius?
  2. jcsd
  3. Aug 27, 2004 #2


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    There is something called the classical radius, which is defined as e2/mc2, and is numerically 2.81777x10-13 cm. In the definition e=electron charge, m=mass, and c= speed of light.
  4. Aug 28, 2004 #3
    There's a Kluwer Publishing book called: "The Enigmatic Electron" by Malcolm MacGregor who used to work for Lawrence Livermore National Labs that has a lot of info on the electron.
  5. Aug 28, 2004 #4


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    The book costs 158$ at amazon.com !!! What's in it that's so expansive?
  6. Aug 28, 2004 #5
    Not sure how to add an attachment yet, so here's part of the TOC.

    Preface: The rationale for the present book

    Part I. The Crisis: Classical vis a vis Quantum Physics
    Chapter 1. Three unanswered questions in twentieth century physics
    A. What is the size of the electron
    B. What is the nature of the electron mass
    C. Are there experiments that reveal the size of the electron
    D. The 1990 Antigonish electron workshop
    Chapter 2. Some new ideas in an old field of physics
    Chapter 3. The breakdown of classical physics in the electron
    A. Conflicts wiht classical EM
    B. Conflicts with SR
    Chapter 4. A possible reunion of classical and quantum physics

    Part II. The natural size of the electron
    Chapter 5. The natural size of an elementary particle
    Chapter 6. The spectroscopic and bulk sizes of the electron
    A. The spectroscopic size of the electron
    B. Bulk measurements of particle sizes
    Chapter 7. The electric sizes and electric self-energy of the electron
    Chapter 8. The magnetic size, magnetic self-energy and anomalous magnetic moment of the electron

    Part III. The Spectroscopic Electron
    Chapter 9. Do we need a spectroscopic model of the electron
    Chapter 10. Spin quantization and the relativistically spinning sphere
    Chapter 11. A classical spectroscopic model of the electron
    Chapter 12. The Lorentz invariance of a finiste-sized electron
    Chapter 13. Spatial quanitization and the two-component rotation group
    Chapter 14. A quantum-mechanical model of the electron

    Part IV. The Mott channeling of finite-sized electrons
    Chapter 15. Mechanical mass: a new state of matter
    Chapter 16. The keV Mott helical-channeling window
    Chapter 17. Experimental evidence for helical channeling

    And some appendices on experiments.

    Hope that helps.
  7. Aug 28, 2004 #6
    The book titled "The Enigmatic Electron" provides these values:

    1. R(E) (point-like charge radius)-------------------<1 x 10-16 cm
    2. R(0) (classical radius)--------------------------2.82 x 10-13 cm
    3. R(C) (Compton sized electron)------------------3.86 x 10-11 cm
    4. R(E) Effective (R(E) = 2/5 RC)-------------------1.5 x 10-11 cm
    5. R(E) Effective - Corr (R(E) = XX R(C)-------------1.3 x 10-11 cm
    6. R(H) (based on Compton radius)--------------------4 x 10-12 cm
    7. R(H) (based on classical radius) -----------------4.09 x 10-12 cm
    8. R(H) QM-Corrected (R(H) = (sqrt of 3)*R(C))----6.69 x 10-11 cm
    9. Scattering results before 1992 imply--------------< 1 x 10-16 cm
    10. Scattering results very recently imply------------< 1 x 10-18 cm

    As state in this boo, the electron experts are currently debating whether or not electrons have a true mechanical mass at the center of the electron which would be much smaller than any electrical charge based radius. There is no direct discussion of the magnetic radius size, but there are a few hints at it.
  8. Aug 29, 2004 #7
    Thanks a lot folks.
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