**Abstract**: A fundamental revision of the accepted Standard Model of Physics has to be performed because neither the assumption of classical physics, the equivalence of inertial mass and gravitational mass, nor the used quantum conditions of microscopic physics appear to be valid hypotheses. The fundamental field (UF) consisting of the electromagnetic field and the covariant gravitational field generated by four types of sources is central in physics. The sources = quanta of the UF are represented through the four stable particles e, p, P and E, having two kinds of Maxwell charges. The source quantization leads to variation principles of open physical systems in finite space-time domains . Beside Planck’s constant h, at least a second basic constant *h ^{0}= 1/4 ⋅ √2^{ }⋅ q²/c* exists which is responsible for the neutrinos as bound states (e,p), (P,E) and for nuclear forces. The source quantization of the UF is resulting in investigations of variation problems within a set of new fundamental hypotheses of physics.

PACS Numbers: 03.70.+k, 04.20.Cv, 12.10.-g, 13.15.+g