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Re: [Phys-L] Particle physics







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On Jun 18, 2013, at 8:44 PM, Ludwik Kowalski wrote:

There is no experimental evidence, as far as I know, that an electon is made of many negatively charged components (for example 10 particles of tiny charge, >q=e/10, and tiny mass, each). Therefore the idea of "electrostatic self-energy of an electron" belongs to logic (mathematics), not to physics. Each new axiom >creates new problems to solve. 
That above-mentioned idea would belong to physics if tiny negative sub-particles were shown to exist in nature. In physics we do not say that electrons are >made from negative subparticles. They are usually introduced as point-like particles. 


  The electrostatic energy of any charge system can be expressed either in terms of the charge density distribution, or (through div E = rho/epsilon), in terms of the corresponding electric field distribution. In the latter case, when we go to the limit of exact localization (point charge) rho (r) ---> delta (r), it becomes immaterial whether the net charge is a compound of smaller parts, or an indivisible unit. In any case, its energy, at least in classical physics, must go to infinity in the point charge limit. As far as Math leading to expression of energy in terms of electric field alone remains valid in this limit, the infinite electrostatic self-energy of any point charge remains a physical problem. Its known "solution" by introducing an "effective electron radius" r_el = e^2/mc^2 is purely formal, and I am unaware of any other  experimental evidence of a finite size of an electron except of its finite rest energy, which pulls us into the vicious
circle. So, to my knowledge, the problem remains an unresolved issue.         

Moses Fayngold,
NJIT

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