I'm not an expert, but my feeling is that it's a little simplistic to say that space and time are the same thing, though they're definitely intertwined in a way that defies intuition. Some people say that the speed of light is the conversion factor between units of space and units of time. I guess by that logic v always = c? Which I happen to believe is probably the case: things traveling at speeds slower than c are actually made up of smaller units of energy that are traveling within the particle in circles (or other circuitous shapes) at the speed of light. For example, in an atom, the "electrons" are propagating around the atom in a de Broglie wave at the speed of light. Or maybe slightly slower, but then, who knows what's happening "inside" the electrons. And then you'd have to make up a similar story for the protons/neutrons or the quarks that make them up, etc.