Solenoidality of a Magnetic Induction Field and Conservation of Total   Momentum
  This scientific essay proposes to discuss the physical aspects of a system consisting of some non-relativistic massive charged particles, that are the sources in motion of an electromagnetic field (e.m.) propagating through the space, filled by a linear, homogeneous, and isotropic material medium. The physical link between the conservation of total momentum and the solenoidality of a magnetic induction field is investigated. After a careful review of all the more widely sustained didactic justifications for the solenoidality of magnetic induction, some properties of the Maxwell e.m. stress tensor are defined according to Minkowski. This study presents a new framework wherein the necessary condition for the free-divergence of magnetic induction in the entire space, here named as solenoidality condition, derives directly from the total momentum conservation of the system, i.e. particles plus field. The theoretical treatise generally leads to results that leave some open questions on the existence, or at least the observability, of the magnetic monopoles. Their observability is theoretically plausible only under suitable assumptions of symmetry that, in the opinion of authors, may be in any case an interesting topic of scientific discussion especially in the field of experimental physics. 
Sergio Severini (1), Alessandro Settimi (2) ((1) Centro Interforze   Studi per le Applicazioni Militari (CISAM) - Italy, (2)...
physics.class-ph