The ideal process of congruent displacement of spacetime distance used in mathematical construction of spacetime geometry is distinct from physical measurement processes.

At first glance it might be surprising that according to the purely close-action geometry, length transfer is non-integrable in the presence of an electromagnetic field. Does this not clearly contradict the behaviour of rigid bodies and clocks? The behaviour of these measurement instruments, however, is a physical process whose course is determined by natural laws and as such has nothing to do with the ideal process of ‘congruent displacement of spacetime distance’ that we employ in the mathemat