According to classical physics (Newtonian Mechanics), the time co-ordinate is unaffected by a transformation from one inertial system to another. The time co-ordinate tʹ of one inertial system does not depend on the space co-ordinate x, y, z of another inertial system, the transformation equation for time being tʹ = t. In relativistic physics, however, space and time are interdependent. The time co-ordinate of one inertial system depends on both the time and the space co-ordinate of another inertial system.
According to Minkowski, the external world is not formed of ordinary three dimensional spaces known as Euclidean space; but it is four dimensional space time continuums known as Minkowski space, where the time or more conveniently ict (Where i is the imaginary number) may be regarded to be fourth dimension. Thus an event in Minkowski space can be represented by four co-ordinates (x1, x2, x3, x4) out of which the first three are space co-ordinates. This four dimensional Minkowski space can more conveniently be represented by (3+1) dimensional space time continuum. So space and time are not independent co-ordinates, but that the description of an event must include its co-ordinates in both space and time. For this reason, special relativity usually is formulated in terms of combined space-time coordinates x, y, z, t. Therefore space and time are treated as equivalent coordinates in special relativity.