ABSTRACT
So many of the stars in the universe are many millions of light years away that it would seem impossible to reach very many of them in a normal life span. However, this ignores the phenomena of time dilatation and length contraction. Suppose that a spaceship leaves the Earth, in a direction opposite to the star, then turns around and accelerates until it reaches a speed υ relative to the Earth. Suppose that it continues with uniform velocity υ relative to the Earth (∑) and passes the Earth when the spaceship is moving with uniform velocity υ at a time t = 0 on a clock on the Earth and a time t' = 0 on a clock on board the spaceship. Relative to the laboratory frame ∑ in which the Earth is at rest, the coordinates of Event 2 are x=103kc, t=t,.
