 However, one can consistently use units in which \(c = 1\) and hold that there is nevertheless a fundamental distinction between space and time as dimensions. On such a view, which is the view that Bondi and Spurgin seem implicitly to be defending, while time is distinct from any given spatial dimension, the contingent fact that \(c\) has the same value in all inertial frames allows us to perform the relevant substitution of variables. However, it does not follow from this that we ought to treat time on a par with any spatial dimension, or that we ought to treat the saptio-temporal interval as more fundamental (in the way Torretti does).