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 add-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

The only way to deal with a dangerous world is to become as dangerous as it, William S. Burroughs.

In recent months, we've been looking at hypothetical planets devoted to a single purpose.

We have looked at hive worlds full of people or entire planets devoted to industry.

We looked at one devoted to farming or to being a fortress in wars, and these are all purposes

devoted to keeping people alive and supplied.

The purpose of the planets will be looking at today

though, of Death Worlds, is trying to kill their inhabitants off. So today we'll

contemplate being on an entire planet devoted to killing you from the moment you step

on it or draw your first breath. It's a popular concept in science fiction, dating back

at least to Harry Harrison's Deathborn

series in the 1960s. Of course, tales of us surviving in harsh environments long predates that,

and lots of adventures and early sci-fi are set in distant dangerous jungles or icy tundras or desolate

deserts. It was natural that we would move those stories into space, and we see hundreds of them

as settings for stories, everywhere from Frank Herbert's classic Doom to Star Wars

Frozen World of Hoth or Jungle World of Digaba.

Frequently on post-apocalyptic future Earths littered with mutants and techno-barbarians,

living among the reguactive ruins.

But what is a death bold?

...