Spatial and temporal congruence in physics

a critical comparison of the conceptions of Newton, Riemann, Poincaré, Eddington, Bridgman, Russell, and Whitehead

pp. 3-65

in: Adolf Grünbaum, Philosophical problems of space and time, Berlin, Springer, 1973

Abstract

The metrical comparisons of separate spatial and temporal intervals required for geo-chronometry involve rigid rods and isochronous clocks. Is this involvement of a transported congruence standard to which separate intervals can be referred a matter of the mere ascertainment of an otherwise intrinsic equality or inequality obtaining among these intervals? Or is reference to the congruence standard essential logically to the very existence of these relations?