The Twin Paradox and the Symmetry Problem in Relativity: A Century of Debates and a New Resolution

The twin paradox, formulated by Paul Langevin in 1911 shortly after Einstein published his theory of special relativity, stands as one of the most enduring debates in modern physics. Despite its status as a "solved paradox" in the standard literature, discussions persist regarding its deeper physical interpretation. This article traces the historical evolution of this debate over more than a century and presents a radical resolution emerging from the paradigm that redefines space as a physical medium. Our paradigm provides a physical foundation for relativity's mathematical formalism while making testable predictions about an asymmetry in relativistic H$^+$/He$^+$ ion collisions. The proposed resolution transforms relativity from an operational tool into a theory derived from deeper physical principles.