Light Perception: Exploring Einstein's Velocity Addition Formula

[KingNothing]

Two spaceships approaching each other, each traveling at 90% the speed of light relative to some third observer between them, do not perceive each other as approaching at 90 + 90 = 180% the speed of light; instead they each perceive the other as approaching at slightly less than 99.5% the speed of light.

Now, I got this from a very reliable source, an encyclopedia to be precise, so I know it's correct and goes according to the Einstein velocity addition formula. My question is, why?

Question 1: Is it because a person can never "perceive" something coming at them faster than the speed of light?

Question 2: Assuming there are people in these theoretical ships, looking at each other, and the ships are traveling directly at each other...Would the two ships crash before a person in one of the ships 'sees' the other ship hitting it (say, 1 cm away)?

Sorry if these questions are unclear, I don't have a big vocabulary of physics terms.

 

[Doc Al]

Originally posted by Decker
Question 1: Is it because a person can never "perceive" something coming at them faster than the speed of light?

It's not a trick of perception, if that's what you mean. According to relativity, the speed of a massive object as measured in an inertial frame cannot equal (or exceed) the speed of light.

Question 2: Assuming there are people in these theoretical ships, looking at each other, and the ships are traveling directly at each other...Would the two ships crash before a person in one of the ships 'sees' the other ship hitting it (say, 1 cm away)?

Why? Since the light from the approaching ship travels faster than the ship itself, it will reach the other ship before the crash.