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 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.

Nothing lasts forever, but to build the truly immense and bright future we often envision,

we may need machines to canimes of thousands of years, or even longer, sometimes much longer, and these sorts

of machines that need to last geological lifetimes are very common in science fiction too.

So often there's a bit of a hand wave as to how in the heck you can keep something

functioning that long.

Indeed, even assuming self-repair mechanisms raises issues like machine equivalence of mutation and cancer, or their ideological equivalence too.

How do we keep a colony on a 10,000-year journey on task and focused on achieving their

original mission?

While keeping in mind that 10,000

years is longer than all of recorded human history, let alone an actual civilization or

continuous organization.

That's more than 100 human lifetimes, 100 centuries, and yet a million years is 100 times

longer than even that.

Truth be told, it's impressive to keep any machine or organization running, let alone

substantively unchanged for a century.

If we're being honest, often even a year is pretty impressive.

So you might have a computer that can assess maintenance needs, but what's maintaining it?

If you're curious, the longest running computer still in use is Faccom, a big super computer

...