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

This episode is brought to you by Brilliant.

Humanity's technological progress in the last few centuries has been staggering,

lifting us up to the heavens above themselves,

but what of our own ingenuity is bringing us ever closer to an inevitable doom of our own making.

No. ever closer to an inevitable doom of our own making. The Fermi paradox is perhaps the greatest mystery to arise from our greater understanding of

life, the universe, and everything, as we develop telescopes

to see distant stars and microscopes to see tiny cells.

The sheer scope of not only life on Earth, but the apparent existence of uncountable trillions

of other worlds that would likely match our basic starting conditions, makes us pause to wonder how, in such

a vast and ancient universe we could possibly be alone.

The sheer scope of that universe is mind-crushing as we try to contemplate how immense

our own planet in history is while still being an insignificant speck in space and time, a tiny pale

blue dot.

Our reality is both terrifying and awesome, and that would surely also describe any civilizations

which arose long before us and crafted kingdoms among the stars themselves.

What technologies and artifices they must possess, what wonders

and horrors could they construct?

And this is our vantage point today, because for good or ill, we do not seem to see those

...