There is another layer. You are not only trying to travel through space, but also time.

We know the formula: s^2 = (ct)^2 - d^2 s: spacetime distance/interval (invariant no matter the observer) c: speed of light t: time d: coordinate in 3D space

Now, let’s say we have 2 travelers who need to meet at a certain place. Traveler A is 1 spacetime distance unit away Traveler B is 2 spacetime distance units away.

If they are both at the same age when they started the journey, B would be younger than A even though A is closer to the destination than B! Because B experienced more time dilation, and A needs to either wait at the destination, or travel slower.

So to meet each other at a relatively same age, B needs to travel slower on purpose, or A can take a detour.

Millions of years become meaningless, people who have no spaceships would be a death sentence. They would never see loved ones again. So in a sense, enormous ships that can travel at near the speed of light are a norm for that type of civilization.

We are unfortunately at a very early time of the universe. If we are born later, we could probably see other civilizations travel to us :D

Space travel is weird. Brain hurty.