My brain just had a memory leak causing my intelligence to work as good as Stephen Hawking's muscles. So being very much ashamed to ask this i'd like some help in understanding what seems logical enough to otherwise understand it myself. Somehow i keep failing while i'm sure i understood this years ago already.
Fact: The speed of light is constant
Fact: Nothing can travel faster than light
Fact: Because the speed of light is constant and distance is relative, time is also relative
Fact: with the exception of true absolute constants, EVERY type of measurement anywhere is relative to an observer
Question:
How can we not travel faster than light then?
Let's take my house as the observer. If something moves to the left at 200000 km/sec (2/3 speed of light) and something else moves to the right at the same speed, they'll be moving away from eachother at a speed of 400000 km/s (4/3 light speed). Obviously this isn't possible.
So how does the relativity in time explain again how these two objects at 200000 km/s are not moving away from eachother at 400000 km/sec?