Magnetic monopole - a hypothetical entity proposed on the basis of theoretical calculations, and duality to electric monopoles.

A magnetic monopole cannot be created by dividing a magnet or magnetic dipole

^{S. Zurek, E-Magnetica.pl, CC-BY-4.0}

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

Animation of field lines around a magnetic dipole and an electric dipole

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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.¹⁾

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

The results of some experiments were claimed to prove existence of magnetic monopoles, but these experiments had to be carried out under special conditions. For instance, the “monopole-like structures” were observed not in magnetic field, but in the so-called “synthetic magnetic field”.²⁾

In a different experiment the “monopoles” were not particles in the same sense as for example the electron, but rather “quasi-particles” or “topological monopoles”.³⁾⁴⁾ So although the behaviour of such structures resembles monopoles in certain aspects, they are not magnetic monopoles in the same strict sense as the electrons and protons are electric monopoles (the most fundamental sources of electric charge existing as isolated subatomic particles).

• Magnetic dipole