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.

All galaxies a dangerous place for life, a vast storm of stars in which new ones are born

and die in deadly displays, as we gobble up smaller galaxies and whole planets are irradiated

or ejected into the void. How much of the galaxy is truly safe for life to be morge in.

Today we'll be examining the concept of galactic habitable zones, both in terms of where

and when life might have arisen, and where we might be able to safely make homes, even with

entire regions of our galaxy being fairly hostile to life.

We will also examine other galaxies and ask if our own Milky Way is more or less hospitable than most galaxies,

and if there were periods where a galaxy might be more or less hospitable, we'll also ask

if this might play a role in the formation of hypothetical alien civilizations. When it comes to the Fermi paradox and the big question of where all the intelligent

alien life is, we have discussed many different scenarios, and the three big ones are that

they hang out here all the time, but we're just blind or in denial, that they are very common,

but we just have problems seeing or hearing them, and that

intelligent life is just very rare, because the so-called Great Filters prevent life forms

from making it through.

This channel has no official stance on which category is right, because none of the proposed

solutions seem without their flaws, but we definitely tilt toward the Great Fil camp, that life may or may not be abundant out there, but that intelligent technological

civilizations are not, either because they occur rarely or that they don't last long when

they do pop up.

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