Ungar, Abraham A. The proper-time Lorentz group demystified. (English) Zbl 1173.83301 J. Geom. Symmetry Phys. 4, 69-95 (2005). Summary: Proper velocities are measured by proper time as opposed to coordinate velocities, which are measured by coordinate time. The standard Lorentz transformation group, in which each transformation is expressed by a coordinate velocity and an orientation between two inertial frames, is well known. In contrast, the equivalent proper-time Lorentz transformation group, in which each transformation is expressed by a proper velocity and an orientation between two inertial frames is unknown. The dignity of special relativity theory requires that every possible means be explored for the solution of a problem so elegant and so celebrated. Fortunately, a so called gyro-formalism approach to special relativity enables the elusive proper-time Lorentz transformation group to be uncovered. Cited in 1 Document MSC: 83A05 Special relativity 22E43 Structure and representation of the Lorentz group 81R05 Finite-dimensional groups and algebras motivated by physics and their representations PDF BibTeX XML Cite \textit{A. A. Ungar}, J. Geom. Symmetry Phys. 4, 69--95 (2005; Zbl 1173.83301) OpenURL