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.nebula.tv slash Isaac Arthur and use my code, Isaac Arthur.

One of the most iconic scenes in science fiction is in Star Wars, the Empire Strikes

back, where Han, Leah, Chubaka, and C-3PO are hiding inside an asteroid cavern from

the Empire, only to realize it's not a cavern,

it's the throat of a giant space monster, the Exogoroth or space slug.

Star Wars isn't noted for its scientific accuracy, and that scene is also notorious for implying

asteroid belts are dense minefields where a pilot needs to dodge rocks constantly

to avoid death, but they're not alone in using giant space monsters, and I'm not so sure

that giant organisms in space is scientifically unrealistic, or even on planets, like the immense

sandworms of Frank Herbert's Doom.

So I thought we might contemplate giant

space monsters in today's Nebula Exclusive for January of 2024, canonically our first episode

for this year. Now there is a noticeable difference between the various cases we'll consider,

as each has different problems with the possible biology, and we can break them into four

loose categories for discussion today.

First, we have our space slugs or space whales living in actual space, which is our main

focus.

Then we have your more classic, kaiju, giant monsters on planets like the sandworms of

Dune or Godzilla.

...