alpha-centauri

Roughly 44% of Sun-like stars have a companion, and the share climbs past 80% for the most massive stars. Binary stars let astronomers weigh stars, produce Type Ia supernovae and millisecond pulsars, and generate the gravitational waves LIGO detects.

The nearest star, Proxima Centauri, is 4.24 light-years away. At Voyager 1's speed the trip would take roughly 75,000 years. Here is what faster propulsion concepts could achieve, and what stops them.