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.

Imagine living on a world where you could see all the story majesty of space,

but it was denied to you by firestorms in the sky in a constant rain of meteors.

Now imagine that world was Earth.

No. Now, imagine that world was Earth. So today we are going to be looking at Kessler syndrome, a cascade effect in orbit

of a planet that clutters it up with dangerous hypersonic debris, and discussing how that

can happen, what you can do about it, and the impact it would have on a world.

In many cases, this impact will be fairly literal too.

A little while back, one of our regular editors on the show, Jerry Gurne, suggested to me that

we might do an episode looking at how Kessler syndrome might happen naturally in orbit of a planet,

and if that might make civilizations

native to such worlds unable to ever pursue space colonization.

I instantly leapt on the idea and put it on the schedule, but it reminded me that I've

been meaning for some time to do a Fermi paradox episode on various scenarios that might

keep a technological species planet- bound, like higher gravity or thicker

skies or several other options, and so we will be doing a companion video to this one, focusing

on those other options for this weekend's Sci-Fi Sunday episode.

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