[AllenG]

Sorry for the stream of consciousness post.

I was listening to a pod cast that mentioned magnetic monopole news stories during 2009.

Here's the stream of consciousness part--I looked up magnetic monopole on Wiki and then found myself reading about Flux Tubes.  And while trying to wrap my head around understanding whatever a Flux Tube may be I had the thought. 

We live in a flat universe, meaning if one travels in a straight line you will never end up back where you started.  A photon will travel in a straight line forever unless it encounters something massive enough to curve local space.  The same is true of an electron stream unless it encounters a magnetic field.

So here's my question: does a magnet loop space back onto itself, at least for electrons, or is a magnet a black hole for electrons?

[LeeE]

"Does magnetism curve space?" is a very interesting question.  If we think that at some point, or under certain conditions, all of the forces can be unified, and if we also view the force of gravity as being the result of curved space-time, then it suggests that space-time geometry is significant, in some way, to the other forces as well.  I dunno the answer to that.

We don't seem to live in a flat universe though.  The options are flat & closed, flat & open, curved & closed and curved & open.

In a flat & open universe, the uninterrupted photon will not return to it's origin.  In a flat & closed universe the photon will be either lost entirely, when it reaches the boundary, or will reappear at a point somewhere else on the boundary, and so may return to its origin (if the photon is lost then eventually everything in the universe will be lost, given enough time).

In a curved & closed universe, the photon will return, but in a curved & open universe it won't.

Whether the photon returns to its origin then, seems to be more down to whether the universe is open or closed and not what shape it is.