I wanted to double check my calculations an interpretation of relativity. Thanks in advance. Two identical ships leave the same point at the same time traveling .999C and travel a 100 light years each but leave on paths that are 10 degrees apart. If the passengers where to compare their time spent traveling to an outside observer they would only show that 4.47 years  have passed compared to the 100 years from the external frame of reference. However, since they have traveled 100 light years on their two different vectors the two ships are now 17.4 light years apart .  let c = 1 and v = .999, then 100 years * (1-.999^2)^.5 = 4.47 years  sin 5 = opp/hyp = x/100, x = 100 * sin 5 = 8.72, so 5 degrees gives 8.72 light year distance and then 10 degrees would be 17.4 light years distance between the two ships after traveling 100 light years.