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2

I think that John Rennie's is a good answer, specially due to the link given where it is shown the reasons why physicists expect the magnetic monopoles to exist. However I would like to stress that this is not simply the case of "explaining the non existence of something that we never saw". It is rather how to explain the lack of observation of something ...


3

The historical basis of this belief is embodied in Gauss' Law: $$ \nabla \cdot \mathbf{B} = 0 $$ This form is widely accepted for classical electromagnetism (as opposed to the form modified to allow for magnetic monopoles). It implies that the net magnetic flux over any surface is zero. A magnetic monopole would cause the magnetic flux of a surface to be ...


6

Within the framework of standard model (SM) magnetic monopoles are non-existent. It is quite subtle as to why this is not the case. To begin, look at the Dirac's famous charge quantization condition. It was first pointed out by Dirac that on the quantum level the existence of the monopole will lead to the \begin{equation} qg = 2\pi n \qquad\qquad \text{...


4

You cannot just add a term to the Lagrangian to give the usual electromagnetic gauge theory magnetic charge. The reason is rather simple: The equation of motion for a magnetic four-current $j_m$ is $\mathrm{d}F = j_m$. But $\mathrm{d} F = \mathrm{d}\mathrm{d} A = 0$ independently of the equations of motion. So simply adding a term doesn't work. The first ...


40

There is no theoretical reason why magnetic monopoles cannot exist and indeed there are good reasons for supposing that they should exist. It's just that we have never observed one. In the past there have been various experiments to detect magnetic monopoles, though I think everyone has given up on the idea by now. If you're asking why we can't get ...



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