(Attention conservation notice (hat tip to Cosma for the term): This post requires some familiarity with Maxwell’s equations to make much sense.)

A recent post by Dave Bacon reminds me of a beautiful old idea by John Wheeler for explaining the electron (and other charged particles) as a combination of non-trivial geometry, and the free electromagnetic field.

Suppose we start with ordinary flat spacetime. Now insert a pair of tiny little punctures, and a little tube connecting those punctures. The tube and the punctures will be used to represent an electron / positron pair.

Now suppose that we have a divergence-free electric field going into one puncture, passing through the tube, and out the other end of the tube.

From the point of view of an observer in the bulk, who is unaware of the puncture, it will look like the electric field has non-zero divergence around each puncture, i.e., it the punctures look like charges.

• The charges of the two punctures are equal and opposite.
• It puts the electric and magnetic fields on an equal footing – there is no charge for either.

Unfortunately, the idea leaves us wondering (a) why we don’t see magnetic charge in the bulk; (b) why charge is quantized ; and (c) what the dynamics of the tubes is supposed to be.

Still, I really like the idea as a simple example of how non-trivial geometries can give rise to interesting physical phenomena.

From → General