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However, travel at 0.1c is not needed for the Fermi Argument to bite. Much slower speeds would allow a colonization wave to sweep a galaxy in time << the age of the universe.

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Even at .0006c (our current tech), the galaxy would be filled with (weakly self propagating) robotic probes after just 750 million years. Unless extremely long lived self-propagating probes just ... die out ... that implies no aliens older than 750 million years from our galaxy. It implies no aliens from the nearby galactic neighborhood within 3 billion years. That kind of implies we're all alone.

I have three wild-eyed theories: (1) eukaryotism is an unbelievably exotic step; (2) and/or the moon is required and ultrarare; or, (3) advanced civilizations eschew yellow stars for being inconveniently short-lived: maybe they prefer brown dwarfs, white dwarfs, or black holes for their energy gradient.

you want a funny one I am starting to like more and more ?

We are simply the first.

Long-lived self-propagating probes are probably impossible. Even out in deep space, mechanisms eventually decay. Building in redundant systems or automated repairs doesn't allow you to cheat the inevitable increase of entropy in that closed system.

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