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.

This episode is brought to you by Brilliant.

In the future, as we journey out to distant stars, we may encounter aliens that are warlike

and aggressive.

On the other hand, when contemplating humanity's past, that might be the pot calling

the kettle black.

Today we'll be continuing our long-running alien civilization series by looking at the

concept of belligerent aliens, and as the title implies, we'll be examining hypothetical

alien civilizations like the Klingons from Star Trek, who all seem to go around with their

jaw-out and eyes blazing looking for a fight, the ones who seem easily offended and utterly

undiplomatic. However, we'll also be examining what sometimes called the biologist's view

and historians take on the Fermi paradox, the big question of where all the aliens are,

that we explored a bit last month in our sci-fi Sunday episode on sentient planets and world

consciousnesses.

In that, we commented that the default perspective of biologists on the Fermi paradox tended to be the Halt conjecture, named for Michael Hurt, the gentleman who coined the term Fermi

paradox, that biological origins incline species to expansionism and belligerence, and so we

would expect most civilizations

to reach incarnize space to share that tendency.

Thus civilizations are probably pretty rare or else the galaxy would be colonized, but

...