"Arbitrary" ("existing or coming about seemingly at random or by chance or as a capricious and unreasonable act of will", "based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something" [1]) is a very poor term. Not only is physics highly constrained by what can be observed in the universe, it is also capable of demonstrating (when it is actually the case) equivalences between apparently dissimilar modes of presentation. It is not perfect, but can you present anything that does better?