Newtonian dynamics was based on the assumption of instantaneous propagation of interaction. Roamer’s studies showed that the velocity of interaction cannot exceed the velocity of light in free space. (c=3x108 mps). Lorentz’ electron theory and electrodynamics take this fact into account. It is possible to rectify the defects of Newtonian theory by deriving Maxwell-Lorentz equations and the Lorentz Force equation for the gravitational field and hence the modified Newtonian dynamics can explain (i) The Perihelion Shift of the orbit of the Planet Mercury (ii) Deflection of light by the Sun (iii) The Gravitational Redshift [1]. It is shown that the use of centre of mass coordinate system also implies a non-elliptic orbit in general, so that the inverse square law of Newton/Coulomb is always valid. Next, the energy and momentum of a dynamical system are shown to satisfy Finally, the Schrodinger’s wave function is interpreted as a quantum mechanical energy density [2].