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

we're asking 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.

This episode is brought to you by Raycon.

So much of our discussions of the future here on this show and elsewhere assume a grand

destiny out among the stars, but what if we were wrong, and that glorious future on

the horizon, is merely a mirage.

A few months back I asked our audience over on our Reddit group, R slash Isaac Arthur,

for some episode ideas, and there were so many good ones that I decided to take five of the most upvoted and put them on our YouTube community page for a poll, and the clear winner

was today's topic, what happens if we cannot leave Earth? One of the things I tend to be

best known for is for talking about how to get us off Earth and to new planets, so I wasn't

a bit surprised by

that being a topic folks wanted me to discuss. Of course, another thing I tend to be well

known for is being pretty upbeat about humanity's future, and as we'll see today,

even if we cannot get off Earth, that doesn't make for a bleak future at all. We don't really

see a distant future on Earth being discussed very much.

Sci-fi in the galactic setting rarely does much here in favor of strange new worlds, and Earth

tends to either be the distant capital of some stellar empire or a distant memory of a world

long since destroyed.

When we do see Earth as the centerpiece of such stories, it is usually the dying Earth saga,

inevitably dystopian stories set in an exhausted planet, which is either spurned by its distant

...