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.

Welcome to the Generation Ships and Interstellar Colonization Series.

Like so many of our series, it began originally with the intent of doing just one episode

on actual Generation Ark ships, and rapidly expanded until at last count it included

10 episodes, the most recent being

fleet of stars, for when you want to move stars rather than move to them.

I suppose there's a couple reasons for that, beyond me just being rather long-winded.

First, everything about generation ships and interstellar colonization just fascinates me.

It's maybe my favorite area of science fiction, and my brightest hope for the future.

I often get asked what technology we discuss on the show I'd most hope to live to see,

and of course I always say radical life extension technology, but that's more of a means to an end.

So to our generation ships, I suppose, since it's those human colonies bravely pioneering

new worlds and creating new civilizations under alien suns that I truly wish to see.

But at the same time, I don't really plan on ever going to those places, even if I live long enough

to be able to. I'm quite fond of earth and have my roots here, so for me the end is those

ships, to be able to wave folks goodbye and wish them a safe voyage, so making that a possibility

for them is my end goal, and getting to read those letters and see those pictures they send

home.

I mentioned a couple of reasons though for becoming a series, and the second one is that

while colony ships are a staple of science fiction, they almost always depend on fast and light

...