Why Finding Aliens Could Doom Humanity

In discussions of alien life in the idea of a so-called Great Filter is one of the most important out there. It not only irrevocably shifted the way that we think about astrobiology, but it is also an idea which is intertwined with the fate of humanity itself. Last episode, we discussed one of the strangest mysteries

[music] in the universe that it seems so lonely. In 1975, Michael Hart stated what he called Fact A, the somewhat trivial observation that the Earth has not been colonized by some expansive alien species. As vapid as that might seem, it's actually one of the most important constraints that we have about alien

life. And so, as we explored last episode, [music] the Hart-Tipler conjecture argues that the best explanation for Fact A is simply that alien life actually never enters a phase of rampant space colonization. So, how plausible is that?

[music] Well, Carl Sagan famously pointed out that aliens won't be in technological lockstep with us. They'll either be far less or far more advanced, [music] which implies that many could indeed easily colonize if they wanted to. Nothing violates basic physics here. [music] So, if it's not for lack of capability,

maybe it's for lack of will. Maybe all alien civilizations out there just simply never choose to expand their presence across space. But this is an example of what astronomer and friend of the channel Jason Wright calls the monoculture fallacy, that any explanation for [music] an absence of

aliens that relies on universal rules of conduct or behavior is simply incompatible with even the diversity of human cultures and behaviors. [music] In a seminal essay in 1993, economist Robin Hanson made a similar comment, writing that humanity has continued to fill new geographic and economic niches [music]

as they become technologically feasible. For example, while Imperial China closed itself to exploration for a time, other competing people such as in Europe eventually filled the gap. This phenomenon is easily understood from an evolutionary perspective. In general, it only takes a few individuals of one

species to try to fill an ecological niche, even if all life is uninterested. In modern discussions, a popular argument is that aliens transcend the physical world and go digital. Perhaps living in some kind of hellish metaverse with a Zuckerberg avatar constantly trying to show you ads for the rest of

eternity. [music] Even back in 1993, Hanson had anticipated this argument too, though, writing that even navel-gazing virtual reality addicts will likely want more mass energy to build and run better computers and should want to spread out to mitigate local disasters.

I think we have to concede that there is no easy way to wave off fact A. It is a stubborn and vital [music] data point, the sharpest edge of the Fermi paradox.

What's wild is that it demands that less than one in a hundred thousand galaxies have ever spawned a marauding expansionist civilization. That's less than one in 10 quadrillion star systems.

So, we require one hell of a great filter here. See the last episode for how we get to that number. Back in 1993, Robin Hanson hadn't done that full calculation, but he punted that this number was essentially the entire observable universe and from that he was left with a deeply disturbing and now