Question

If 2 spaceship fly in opposit directions at 99.9% of speed of light what is the distance between them would be in …?

Answer 1

assume that at the zero point time in 1 seconds the ship will be 2 light seconds away from each other, but in their local time after 1 second they will be 1 light second away from each other, this looks like a contradiction, because the local time at the ships will tick slowly compared to the zero point time, so they have got to be much farther from each other in 1 second of their local time. 
And for spaceship B relative velocity of spaceship A will be given by


So distance travelled by spaceship A wrt will be 0.999% of c in 1 sec and vice versa.