23.11.2014 Views

Single-Particle Electrodynamics - Assassination Science

Single-Particle Electrodynamics - Assassination Science

Single-Particle Electrodynamics - Assassination Science

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

4.2.2 The magnetic-charge dipole<br />

Magnetic monopoles are incompatible with a simple Lagrangian description<br />

of the electromagnetic field; they cannot be described by a unique fourpotential<br />

A(x). They have never been observed experimentally. All known<br />

magnetic dipole moments have been shown [115] to most definitely not arise<br />

through the presence of magnetic monopoles. The author does not believe<br />

that magnetic monopoles exist in our Universe.<br />

But Newtonian mechanics does not care for any of this: it does not use the<br />

four-potential; it does not worry about what has and has not been discovered<br />

by mankind; and it most definitely couldn’t care less about the author’s<br />

opinions. Moreover, the Maxwell equations of Newtonian mechanics seem<br />

to have a gaping asymmetry, which arguably could be filled by inserting<br />

“magnetic charge” and “magnetic current” source terms into these equations.<br />

Thus, despite the author’s disbelief in the physical usefulness of magnetic<br />

charge, we shall nevertheless consider here the Newtonianly acceptable model<br />

of a magnetic dipole as simply being the dual of the electric dipole: two equal<br />

and opposite magnetic charges on the ends of a stick. The reasons for doing so<br />

are fourfold. Firstly, it has been historically common to consider such objects,<br />

and no discussion would be complete without such a review. Secondly, it is<br />

a simple analysis, being simply obtained from the electric result by means<br />

of a trivial duality transformation. Thirdly, we shall begin to appreciate the<br />

desirable features of the resulting equations of motion, despite the fact that<br />

the model is unphysical. Fourthly, the final equations of motion we shall<br />

find, in this chapter, will turn out to be identical to the magnetic-charge<br />

model—with one, beautiful addition.<br />

Let us therefore immediately take across the results of the previous section,<br />

by using the electromagnetic duality transformation<br />

E −→ B,<br />

B −→ −E,<br />

128

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!