Re: EPSILON_ZERO, OK ?

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Regarding Leigh's comment:

> Dirac's paper also showed that if there existed even one monopole in the
> Universe its charge was determined (to within an integer multiple) by the
> quantization of angular momentum in the electromagnetic field.

As I recall the result had nothing to do with angular momentum (although
the quantum of action, h-bar, does appear).  Rather, he showed that if
(in cgs Gaussian units) there is any isolated electric charge q_e and
there is also any isolated magnetic charge q_m anywhere in the universe
then the product q_e*q_m was quantized as q_e*q_m = [integer]*h-bar*c/2.
This quantization condition came about because of the need to have the
particle wave functions single-valued throughout all of space.  This
quantization condition has a consequence that if there happened to be any
magnetic monopole anywhere in the universe then all electric charges in
the universe must be integer multiples of a fundamental electric charge
e = h-bar*c/(2*q_m).  If we invert this expression and solve for
q_m and use the experimental value of the fine structure constant we get
a value of q_m which is (137/2)*e.

David Bowman
David_Bowman@georgetowncollege.edu