1907: Hermann Minkowski defined the relation between the four-force (which he called the moving force) and the four acceleration m d d τ d x d τ = R x , m d d τ d y d τ = R y , m d d τ d z d τ = R z , m d d τ d t d τ = R t {\displaystyle m{\frac {d}{d\tau }}{\frac {dx}{d\tau }}=R_{x},\quad m{\frac {d}{d\tau }}{\frac {dy}{d\tau }}=R_{y},\quad m{\frac {d}{d\tau }}{\frac {dz}{d\tau }}=R_{z},\quad m{\frac {d}{d\tau }}{\frac {dt}{d\tau }}=R_{t}} corresponding to m A = F {\displaystyle m\mathbf {A} =\mathbf {F} } .
1907: Hermann Minkowski definierte die Beziehung zwischen der Viererkraft (die er als bewegende Kraft bezeichnete) und der Viererbeschleunigung. m d d τ d x d τ = R x , m d d τ d y d τ = R y , m d d τ d z d τ = R z , m d d τ d t d τ = R t {\displaystyle m{\frac {d}{d\tau }}{\frac {dx}{d\tau }}=R_{x},\quad m{\frac {d}{d\tau }}{\frac {dy}{d\tau }}=R_{y},\quad m{\frac {d}{d\tau }}{\frac {dz}{d\tau }}=R_{z},\quad m{\frac {d}{d\tau }}{\frac {dt}{d\tau }}=R_{t}} entsprechend m A = F {\displaystyle m\mathbf {A} =\mathbf {F} } .