"The Starshot initiative aims to send a probe to the nearest starsystem..
so we can learn from up close wether it has life there. The idea is to send the probe so it will reach there within our generation. And since the nearest star is four lightyears away, it means that it takes light four years to breach the gap between the sun and that star. So if we want the spacecraft to reach the star within lets say 20 years, it needs to move at a fifth of the speed of light."