Before moving on to the fourth point, I would first have to do some house-cleaning on a vital concept in Einstein’s theories — the Fourth Dimension. Sounds real sci-fi and ominous, doesn’t it?
First, the three dimensions that we know of are 1.) Up and down, 2.) Left and right, and lastly 3.) Backward and forward (or near-far, in-out). Together, these three make up space. So what’s the fourth dimension? The answer is time. Together with the three dimensions, they make up what we know as space-time. No, time-space warp from Shaider is whole different thing.
According to Hermann Minkowski (he was the one who proposed the existence of the fourth dimension, by the way), the reason objects shrink when they’re moving is like the reason why shadows change in lengths. It’s all a matter of angle. Things appear shorter in space but in space-time, it’s just a matter of a change in angle. Imagine yourself in a 2D world where all you see is up-down and left-right. All you’d see are lines and edges without depth and such. It’s just like that: a matter of perception. Thus, changes that happen to time may also be seen as shifts in space-time.
This pretty much sums up our fourth point: space and time are linked.
Oh, reminder, though. As always, all this business about shrinking depends on the observer. Remember our central dogma about relative motion. This means that if you were moving with the javelin, it wouldn’t shrink in your eyes at all.