shall be an invariant with respect to the transformation. This condition is satisfied only by linear transformations, that is, transformations of the type
in which the summation over the
is to be extended from
= 1 to
= 4. A glance at equations (23) and (24) shows that the Lorentz transformation so defined is identical with the translational and rotational transformations of the Euclidean geometry, if we disregard the number of dimensions and the relations of reality. We can also conclude that the coefficients
