Narrator: So, you're planning your next vacation to the cosmos. You've picked out a few potential places to go, you've marked your map…
…and you've also somehow rigged up your spaceship to...travel at almost the speed of light?
How did you...so how are you going to...uh..
Well, here we go, I guess!
Before you fly off all willy-nilly, however, there are some important things you should probably know about approaching the speed of light.
First, a lot of weird things can happen, like time and space getting all bent out of shape.
For example, If you’re moving at nearly the speed of light, according to the clock inside your rocket, you’ll only take a bit more than half the time to reach your destination compared to what a clock on your planet would say. The end result is that while your clock might move normally to you, you’d see the clocks back home had moved further when you return, so you might want to reschedule your dental appointments before you leave.
Also, because you’re going so fast, what would otherwise be just a few hydrogen atoms that you’d run into quickly becomes a LOT of dangerous particles, so you should probably have shields that keep them from frying your ship and also likely you.
And finally, you wouldn’t want to accelerate too quickly toward the speed of light, because, well.
However, since it looks like you’ve figured all that out already, let’s talk about how long it takes to travel around the universe.
While you will be traveling very fast, the universe is also a very big place, so you might be in for some surprises. For example, even though you’re traveling at almost the speed of light—and, as you remember, the time and space weirdness will make the distance seem shorter to you—your rocket’s clock will still say it takes a bit more than nine months just to get from the Earth to the edge of the solar system. According to a clock on Earth, it’s even longer—
over a year and a half. That's not too bad, but to get to the next star system, your clock would say it took you just over 2 years.
If you want to get to farther-out vacation spots, however, you’ll probably need more than a few extra snacks. A trip to the Andromeda galaxy, our nearest large neighbor galaxy,
could take over a million years, and a trip to the farthest known galaxy where it currently is
might take over 15 billion years, which…is more vacation time than I think I’ll ever have.
Of course, again, since time gets all weird the closer you get to lightspeed, your actual travel time will be...um...a bit shorter than that… depending on…just a couple of…
That’s something we can talk about later.
Either way, that should sum up some of the big things you might run into with near-light-speed travel.
But in the meantime, make sure to buckle up, enjoy your snacks, and please…be safe out there.