Ludwig Lange (born 21 June 1863 in Gießen; died 12 July 1936 in Weinsberg) was a German physicist.
He was the son of the philologist and archaeologist Ludwig Lange and his wife Adelheide Blume.
In 1936 he died in a psychiatric hospital (Klinikum am Weissenhof) in Weinsberg.
DiSalle describes Lange's definition in this way:[2] An inertial system is a coordinate system with respect to which three free particles, projected from a single point and moving in non-coplanar directions, move in straight lines and travel mutually-proportional distances.
The law of inertia then states that relative to any inertial system, any fourth free particle will move uniformly.