Erlangen 2026 – scientific programme

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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 11: Various Topics in Relativity

MP 11.7: Talk

Thursday, March 19, 2026, 17:45–18:00, KH 00.015

Rest length and dilated time in five-dimensional spacetime — •Roland Alfred Sprenger — Herford, Germany

This talk presents a geometric method for determining time dilation and proper length of relativistically moving bodies without the use of an affine coordinate system or scale transformations. Based on special relativity, a five-dimensional spacetime is introduced in which the constructions can be formulated consistently. The additional dimension is timelike and serves to accommodate time components that lead to formal mixing of spatial and temporal quantities in four-dimensional representations. Time dilation and proper length follow from simple geometric relations, with simultaneity defined by light spheres rather than spatial hyperplanes. The rest frame of the moving body appears as a reference system rotated about the time axis. Superluminal velocities may occur, but they affect only components associated with the additional timelike dimension and not the observable spatial direction.

Keywords: fifth dimension; rest length; time dilation