Unobservability of magnetic monopole

We show that the magnetic monopole (and the dyon) is unphysical by proving that it always involves the unphysical gauge field component. Thanks to their topological nature, monopoles are not affected by continuous radiative corrections, so their perturbativity is guaranteed, and therefore they are unobservable. We then discuss the phenomenological consequences. So far, it was believed that the inflation must occur after the generation of $U(1)$ gauge theory through spontaneous symmetry breaking so as to avoid the overclosure of the Universe by the monopoles. Our conclusion therefore removes this constraint, since they have no physical effect. We list some scenarios which can be resurrected through our discussion, notably those related to the Pati-Salam model. We also demonstrate that the unobservability of the monopole and its condensation, which is the criterion of color confinement, are not inconsistent.