The relationship between gravitational potentials, black holes and the squared light speed c² is examined in this paper as well as the implications of the presented findings for the universal gravitational constant G and general relativity theory. It is common knowledge that the velocity limit in our universe is defined by light speed c and as shown in this work c² plays a similar role for the gravitational potential since c²/G is linked to the mass density of black holes and our local Hubble sphere. Furthermore, it is demonstrated that the rift between cosmology and quantum physics can possibly be reconciled by acknowledging the physical meaning of the Planck units which proposedly define the characteristics of a quantized space-time, including its gravitational impedance. This notion is also supported by the presented logarithmic relationships between the cosmological scale and the quantum scale. Moreover, the presented findings uncover a previously unknown physical meaning for the constituents of Dirac's mysterious large number hypothesis.