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If anything, I would think their 'Great Filter' would be the ability to move outside of your solar system, especially finding/arriving at another one capable of supporting your life. The closest possible Earth-like planet we've found is 13 light-years away. If it's even capable of supporting life. Assuming we could manage even half-lightspeed travel, that's 26 YEARS of traveling, which would require some very dedicated people. And quite a lot of them, to successfully colonize, and reproduce and be able to expand without inter-genetic issues. All of whom need to survive that trip, not just physically but mentally as well. How do you shield against galactic cosmic rays? How do you feed and water everyone? How do people not go crazy being cooped up in their spaceship for years?

I would hazard a guess that there are plenty of civilizations that have reached our level. Many that have probably been able to terraform their Venuses and Mars-es. But making it to another star system is a massive step above that.

Actually we’ve got a solid answer to the Fermi Paradox: space is big, no bigger than that, and traveling through it even at the speed of light is very very slow. Assuming our very first radio transmission were out there in a way that was receivable (it isn’t, it was strong enough, but pretend), less than 1/10 of 1% of the volume of the Milky Way would have been “exposed” to that transmission and thus have the ability to find out humans exist. And of course that’s just THIS galaxy, there are more other galaxies in the universe than there are stars in ours, and none of them have a chance in hell of ever finding out we exist (well OK, I suppose we could do something that made a big light and they could see it billions of years from now). Alien races could be “next door” in the scale of things and never find out about us, or vice versa.

Then of course you have all the other potential problems. But really, space is big, “they” could be all around us and nobody knows about each other.

I think an important point not mentioned is the matter that constitutes stars and planets needs time to coalesce.

The first few billion years stars were made of hydrogen turning into helium. Hardly no heavier elements existed. Heavier elements like carbon, oxygen, silicon, iron, et al are made when an exceptionally dense star goes super nova, turning their hydrogen-to-helium generators into producers of even denser elements like carbon and oxygen. You know, the stuff life as we know it is made out of. And even if you postulate life based on other elements rather than carbon, say silicon, it still takes several births, dramatic deaths and rebirths of stars to make enough.

So planet X, 8 billion years old, may not have existed. Where would all the silicon, carbon, iron and oxygen come from, to make up such a body?

Perhaps rocky worlds took a lot longer to evolve themselves. Up until maybe 2/3rds of the life of the universe, planets were mostly gas giants because only hydrogen and helium was abundant enough elements to coalesce around a new star.

Which makes the Earth fairly new in the abundant-enough-elements-to-make-a-rocky-world planet. And then it took a few billion years to make life.

And here we are. We got here as soon as we could, which, to paraphrase Gandalf, is when we arrived precisely when we meant to.