Magnetic monopole

Magnetic monopole - a hypothetical entity proposed on the basis of theoretical calculations.

Gauss's law for magnetic field is often given in a differential form:

$$\nabla\cdot\mathbf{B} = 0$$

where: ∇• denotes divergence, and B is the magnetic flux density.

As a consequence of this equation there should be no "magnetic charge" or magnetic monopole, and all magnetic fields should be produced by magnetic dipoles.

However, Paul Dirac showed theoretically that the existence of magnetic monopoles would explain why the electric charge is quantised, which so far also remains unexplained.

The search for magnetic monopole continues and no evidence was yet found for its existence.