Re: [Phys-l] Relativity Question about spring

[John Denker <jsd@av8n.com>]

On 05/15/2007 01:51 PM, Hugh Haskell wrote:

>  The implication of Scheider's position 

I don't think Scheider gets credit for it.  The idea goes back to
Poincaré in the earliest years of relativity, nineteen-ought-something.
There is a nice, accessible discussion in Feynman volume II chapter 27
("Field Energy") and chapter 28 ("Electromagnetic Mass").

> is that the mass of these 
> particles is due to the energy contained in the fields surrounding 
> them. I'm not sure that is possible.

If you restrict attention to length-scales larger than the
classical electron radius (which is 10^5 times smaller than an
atom) and don't ask about the force of an electron on /itself/,
and consider only /changes/ in the energy, as opposed to the
total energy in the field, it all works fine.

The idea of field energy is well tested in connection with
electronics, motors, and a gazillion other things.  There's
nothing going on in a spring that would call this into
question.

>  Assuming that the electron is 
> truly a point particle 

That's irrelevant to the discussion of springs.  Rather than
talking about the bare electron, talk about the /dressed/ electron
that carries its Coulomb field along with it.