Space is the next frontier of human exploration. While the events transpiring on Earth at this moment are of critical importance to our species, exploration of space is where our descendants will find glory, fame, and the next home for our species.
However, they’ll have to combat a particularly thorny reality about space travel: space is really, really big, and our fastest spaceships aren’t all that fast in the grand scheme of things.
Let’s put it this way: the closest star system to Earth is Alpha Centuari, a triplicate star system composed of Alpha Centauri A, Alpha Centauri B, and Proxima Centauri. If you could travel at the speed of light, you’d reach Proxima Centauri in about four years. However, we can’t even travel at half the speed of light: using our fastest ships, it would around 17,000 years to reach Alpha Proxima.
It’s important to remember that space is unfathomably big. No matter how much rocket fuel you put in a space ship, it’s tough to approach speeds that even make space travel feasible. As Einstein’s theory of relativity shows, the speed of light is the upper limit to how fast you can move in the observable universe. Without some other law of physics that science hasn’t discovered yet, we’ll always have to follow that universal speed limit.
However, we can probably get close to it with the right setup. The fastest we can launch a ship out of our own solar system is through using a slingshot orbit around the sun.
The way this works is by having a spacecraft approach the sun at an angle until it falls into the sun’s gravity well at a steep angle. Then, swinging around the massive celestial body, the craft would “slingshot” around, taking on some of the sun’s kinetic energy (thanks, gravity!) and launching the ship into space at a much higher rate of speed than it started at.
Theoretically, a single star isn’t the fastest slingshot assist you could get from the natural world. Binary star systems, where two stars are locked in a synchronous orbit with one another, would be among the best naturally-occurring systems to get a slingshot assist from.
The right orbit could take a ship between the two stars at the apex of their swing around one another, allowing a craft to be whipped to speeds approaching reasonable fractions of lightspeed.
While this would require us to actually reach a binary star system, it would mean traveling nearby space in a matter of hundreds of years rather than thousands. Colony ships full of human explorers could traverse the stars in generations instead of epochs. It’s not as exciting or flashy as science fiction, but it might be the future our own descendants someday know.