adjective: (physics) Of an subatomic particle that is identical to its antiparticle; includes all gauge bosons except the charged W-boson and quarks.
Normal Subgroup: In abstract algebra, a normal subgroup (also known as an invariant subgroup or self-conjugate subgroup) is a subgroup that is invariant under conjugation by members of the group of which it is a part.
Normal subgroups are important because they (and only they) can be used to construct quotient groups of the given group. Furthermore, the normal subgroups of G are precisely the kernels of group homomorphisms with domain G, which means that they can be used to internally classify those homomorphisms. https://en.wikipedia.org/wiki/Normal_subgroup
Conjugation: In abstract algebra an inner automorphism is an automorphism of a group, ring, or algebra given by the conjugation action of a fixed element, called the conjugating element. They can be realized via simple operations from within the group itself, hence the adjective "inner". These inner automorphisms form a subgroup of the automorphism group, and the quotient of the automorphism group by this subgroup is defined as the outer automorphism group. https://en.wikipedia.org/wiki/Inner_automorphism
James Clerk Maxwell
"9 coefficients determine the relationship between flux and intensity
6 of these coefficients form 3 pairs of equal quantities
3 pairs of equal coefficients will self-conjugate." [James Clerk Maxwell]
The original quote from "https://svpwiki.com/pdffiles/A_Treatise_on_Electricity_and_Magnetism.pdf - vol. I".
"The case in which the components of the flux are linear functions of those of the force is discussed in the chapter on the Equations of Conduction, Art. 296. There are in general nine coefficients which determine the relation between the force and the flux. In certain cases we have reason to believe that six of these coefficients form three pairs of equal quantities. In such cases the relation between the line of direction of the force and the normal plane of the flux is of the same kind as that between a diameter of an ellipsoid and its conjugate diametral plane. In Quaternion language, the one vector is said to be a linear and vector function of the other, and when there are three pairs of equal coefficients the function is said to be self-conjugate." [James Maxwell, A Treatise on Electricity and Magnetism - vol. I]