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.

In the future, we may settle billions and billions of planets across this galaxy and maybe beyond,

but might these be eclipsed by far greater numbers of megastructure habitats?

Hello, everyone, and welcome to Science and Futurism with Isaac Arthur, as we celebrate

reaching 750,000 subscribers to our show shortly before we celebrate nine years of this show next

month.

As you may know, that first episode was a summary of types of megastructures, and we did a new

and improved version last year, the Megastructure

Compendium, our longest episode to date, and the only one with someone else, my wife Sarah,

helping do the narration. While I was producing that episode, I realized that it had left

out a key piece of discussion that the first episode had, about why our future might see us preferring

mega habitats over terraforming planets and the pros and cons of both, and the overlap too,

as some megastructures are essentially planets. Indeed, some like the birch planets are the

biggest planets you could ever make. We had also just gotten data back from Nebula,

or streaming service,

that folks were performing short bonus episodes over extended editions specifically,

which we have been doing the prior year, so I decided to make Plans versus Megastructures

as an episode there, and have been making around one of those a month since. And while I like

having that extra content for our paying audience, and some of those

...