Small-scale physics called quantum mechanics is still incompatible with large-scale physics as developed by Einstein in his general relativity theory. By using twin physics, which is a dualistic way of considering the universe, and following Einstein’s later advice, it is possible to create a bridge between these extremes. The formulation is carried out using complementary language in which time and space necessarily occur as two distinct qualities, although they are treated analogously. The basic item in the theory is the Heisenberg unit (H-unit), which is defined as a constant amount of potential energy, supplied with mathematical attributes; by interaction with another H-unit, these attributes may be transformed into real phenomena. With this theory, a photon can be described such that its velocity is constant without using the related postulate, showing how the speed of light is the link between small- and large-scale physics. The existence of Planck’s constant emerges from the explanation. The photon is related to a massless electron, which is described by the mirrored interaction of H-units.