Hello all. I asked this question as a sub-question in another thread where it was perhaps inappropriate. It is very basic but the more i try to understand relativity the nearer to the absolute basics i need to go. The more i learn the less i seem to actually understand. When length and time are transformed between inertial frames in relative unaccelerated motion are the underlying dimensions of spacetime transformed. Does the way i have put the question make any sense. Of course this question leads naturally on to other questions regarding the "reality" of length contraction and time dilation but i'll take it one step at at time. Thanks Matheinste.