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What do you think the Great Filter is? (self.asklemmy)

submitted 4 months ago by Cryophilia to c/asklemmy

246 comments fedilink hide all child comments

The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.

https://en.wikipedia.org/wiki/Great_Filter

The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, "If life is so easy, someone from somewhere must have come calling by now."

https://en.wikipedia.org/wiki/Fermi_paradox

Personally I think it's photosynthesis. Life itself developed and spread but photosynthesis started an inevitable chain of ever-greater and more-efficient life. I think a random chain of mutations that turns carbon-based proto-life into something that can harvest light energy is wildly unlikely, even after the wildly unlikely event of life beginning in the first place.

I have no data to back that up, just a guess.

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[–] Cocodapuf 1 points 4 months ago* (last edited 4 months ago) (1 children)

That's definitely the right question! And honestly we don't know, but it's evident that we are first.

Given the age of the universe, statistically it should have already happened by now.

I'm not sure that's true... I'm pretty sure that our sun is old for a main sequence yellow star in our galaxy. When you compare how long it takes for a star to get to the point ours is now, compared to the age of our galaxy, I believe it suggests that sol is part of a first wave of stars of its type. So if life really requires a star like this one to start up, then intelligent life starting just now could be right on time.

Now why is our start perfect for life? Again, we don't know, but evidently it is. Sadly we only have this one data point, this is the only star where we know there's life. So assuming that something about our type of star is perfect is about as sensible as assuming that life could start around any star. Is it that other kinds of stars produce too much radiation in the Goldilocks zone? Or is it that other kinds of stars are too variable in the amount of heat they produce? Or that other kinds of stars don't tend to have rocky planets? We don't know, but something about main sequence yellow stars could be special, and we have one of the first of those stars in this galaxy.

So declaring "we're the first" requires some assumptions, but they aren't crazy assumptions, and a lack of evidence of other older civilizations makes those assumptions stronger.

And to your point, the universe is much older than this our star, so I suspect intelligent life has developed many times before us, at least in older galaxies. But sadly I don't expect us to ever meet life from another galaxy. While I think stars within a galaxy are close enough for travel between them, galaxies are very, very far apart. I don't think life has much chance of traveling to other galaxies, at least not without some method of ftl travel (which I am also not optimistic about).

[–] [email protected] 2 points 4 months ago

It might have something to do with the available elements.

We live in a population I star system, full of crap spewed out from long dead stars. Perhaps it is exactly this crap (like copper, iron, nickle, manganese, and possibly the bulk of carbon and nitrogen) that allow life to develop with enough agility to survive mass extiction events with any kind of complexity.

Or perhaps it's exactly those mass extiction events that have allowed enough breathing room for new paradigms to take hold. Maybe our 5-7 mass extictions that didn't end life entirely are exactly what is needed to prevent stagnation. We just happen to be on the edge of dead and too slow.