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.

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They say in space, no one can hear you snore.

Of course, they also can't hear you firing doomsday devices at their planets when you wake

up to

find your galaxy has been colonized by upstart apes while you slept.

So today we are returning to the Alien Civilization series to explore the concept of civilizations

which spend a lot of time of sleep or hibernating.

This is one of the more common explanations

we see for the Fermi paradox in science fiction, as it explains a galaxy which is full of some

ancient alien menace, but in such a way that we can somehow also exist to get in a fight with

them. What you would normally expect is for them to have crushed us before we ever discovered

fire, let alone rocketry.

If on the other hand they go dormant for a millennia at a time, waking sporadically, this

works better and also better matches with our current observations of the galaxy, which

is to say it seems to be fairly empty of enormous and powerful alien civilizations.

We can see examples of this scenario everywhere from games like Mass Effect, with the Reapers,

...