I'm going to piss off a lot of you by saying this, we are most certainly alone in this galaxy and there's a notable chance that we are the most intelligent beings in the observable universe. We will never encounter aliens or alien life.

The Rare Earth hypothesis has such a strong basis that it can't truly be refuted and it's the most probable explanation for Fermi's paradox. All of our current knowledge, the recent findings and plain logic suggests that abiogenesis and the evolutionary path to intelligence must be astronomically rare. I know that people get their mind twisted when they think of how big space is, but just consider for a while how improbable abiogenesis must be by chance, then consider how improbable were the events that led to our existence or even just multicellular life. There are a lot of unknowns and we must take a notice that abiogenesis probably has only occurred on this planet once or at least only during one short period of our planet's early history. Recently, there's been quite a lot of research on the possibilities of alternative biochemistry, but they've just gotten blown the fuck out, the latest was silicone based life which was hypothesized as likely impossible. Then there's the recent Oxford study which practically concluded that intelligent life must be extremely rare.

Then there's that Earth is surprisingly unique in a sense, especially when we consider Earth as a whole, as a part of the Solar system. Then there's galactic habitable zones and so on which vastly limit the vastness of the universe and the places which could support life.

I know that people like to bring up the "possibility" of life's extraterrestrial origin in this conversation, but that's just a naive argument. Firstly, abiogenesis would've had to happen elsewhere and somehow life should've survived an enormous impact and radiation in space...

There's no aliens, that's the most likely explanation to Fermi's paradox.