Okay, suppose we have a pair of spacecraft. Each is accelerated towards the other one until they both are at 90% of the speed of light (relative to their respective launching sites).
Then, there is another pair, exactly the same, except they both are accelerated to 60% of the speed of light (relative to their respective launch sites).
At this moment, each pair of ships is exactly 1 million miles away from the other ship in the respective pair. (The two pairs are parallel; they won't hit a ship from the other pair.)
So, given that the relative speed between the two ships in a pair cannot be at or over the speed of light, which pair of ships will collide first? Or will they hit at the same time?
Then, there is another pair, exactly the same, except they both are accelerated to 60% of the speed of light (relative to their respective launch sites).
At this moment, each pair of ships is exactly 1 million miles away from the other ship in the respective pair. (The two pairs are parallel; they won't hit a ship from the other pair.)
So, given that the relative speed between the two ships in a pair cannot be at or over the speed of light, which pair of ships will collide first? Or will they hit at the same time?
