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.

Planets are nice, but they are small, messy, and rare. In space, we can build habitats

bigger than anything nature ever made. The question that isn't whether we can build giant

space habitats, but rather just how big they can get or physics tells us no.

Why stop at a space station we can build homes bigger than planets?

For over a century, science fiction engineering visionaries are twitted the idea of habitats

that don't just keep people alive in space, but create entire new small worlds, landscapes,

not buildings, off the size of towns or entire

counties, but our imaginations can conceive habitats larger and grander than anything nature ever

gave us, and we wonder if we can build such things in a known science. So today we're going

to ask, how big could a space habitat get? We'll be focused on megastructures designed specifically for living in space, giant artificial

worlds that provide their inhabitants with air, water, farmland, and even gravity.

A couple years back, we explored a wide catalog of such ideas in our megastructure compendium,

a grand tour of cosmic scale construction.

Many of the designs were touched on today, from neil cylinders to ring wards and wardhouses,

already have their own dedicated episodes where we dive deeper into engineering details.

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