Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asked at the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

When your home doesn't want you anymore, the stars might be your only refuge, and your

greatest challenge.

One most common topics on the show is space colonization, heading out to settle strange new worlds under alien suns.

But part of that conversation is asking not just about the technical aspects of how to journey to a new world,

build settlements, and tear from that planet, or forge that space habitat.

It is also about the motivations and forces in play,

causing people to settle in space. But what happens when the urge to leave is not entirely

your choice, when exile, not exploration, is the driving force behind colonization? And could this

end up being the primary motivation for settlement?

On the one hand, there are a lot of inherent human psychological factors that press us to explore

and colonize new places. Evolution tends to produce creatures that grow, explore, and expand,

and humanity as a whole has a strong tendency to look over that

next horizon, pioneer of the frontier, and build new homes and civilizations.

Humanity's restless spirit has always been its compass, pointing toward uncharted horizons

and untold challenges. Our willingness to tackle and overcome these challenges is part of what

makes us great. On the other hand, space is unimaginably vast, and the times and energies

involved in traveling to these new frontiers are beyond merely huge. I don't doubt that we

will settle this solar system, but the distance to the nearest star

...