From the mass-energy equivalence, the energy of a mass moving with velocity V is given by the zeroth component of its four-momentum. In this study, we re-examine this expression and demonstrate that its mathematical formalism admits an additional speed parameter, c2, determined by the experimental speed of light c1 and the object’s velocity V. Under a set of speculative assumptions—specifically, that energy remains invariant for a mass transitioning between hypothetical “adjacent” universes—the presence of a second mathematical root c2 suggests the existence of a potential alternative state. In this paper, we explore the speculative possibility that this root describes the physical constants of a coupled adjacent universe. This study explores the mathematical curiosity that the energy of a mass at velocity V is identical whether the invariant speed of the system is c1 or c2. Our framework indicates that for low values of V, c2 is less than c1, with the relationship reversing beyond a certain critical velocity. If this mathematical duality corresponds to a physical reality, the electromagnetic properties of such an adjacent universe, including vacuum permittivity (ε02) and permeability (μ02), would be constrained by the relation ε 02 μ 02 =1/ c 2 2 . This exploration is presented as a theoretical inquiry into the implications of the algebraic structure of relativistic energy-momentum relations. 1. Introduction In 1864, Maxwell demonstrated that light is an electromagnetic wave, calculating its speed as c 1 =1/ ε 0 μ 0 [1]. According to Maxwell’s equations, the speed of light is a vacuum constant, invariant for all observers regardless of th... [7348 chars]