If time were relative even though its movement is perpendicular

(at right angles ( _| )) to the length is contradictive. Time moves in the exact same pace, but length can be proven throught pythagoras, is contracted.

If time had shortened, then compared to what? A still system? Einstein also stated clearly, that there cannot be any such system. (according to what I've heard)

Let's expand this to the trippling problem: one moves in speed V1, one in V2, and the third in V3.

So given there is no certain still system there is no time difference between the 3 objects. Just like when you move x wise, the z coordinate is still the same length, and so is time aswell. Time is simply a perpendicular dimension to the lengthcontraction. It isn't dilated any at all.

Why don't you guys dispute that, will you?