What do you think the Great Filter is?

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.

HANN ,

Even if you had a super intelligent species that can make Dyson spheres and travel at the speed of light the observable universe is beyond vast. I don't know much about cosmology or our ability to detect light but given humans have only been looking into the sky for a couple centuries, not being able to see a thimble in the ocean seems like a non issue. I think if you scale the observable universe down to the size of earth the speed of light becomes 0.05 mph.

pelletbucket ,
@pelletbucket@lemm.ee avatar

sentience. I think it usually immediately leads to suicide

pelletbucket ,
@pelletbucket@lemm.ee avatar

evidence of human existence has only gotten what, 150 lightyears out into space?

Cryophilia OP ,

Eh. The amount of oxygen in out atmosphere is pretty much impossible by non-living processes alone iirc. Anyone who can do astro-spectroscopy can probably tell there's life here, from thousands of light years away.

pelletbucket ,
@pelletbucket@lemm.ee avatar

and if life is as abundant as we think, how are they going to tell the difference between intelligent and non-intelligent life

Cryophilia OP ,

Life is so rare, finding ANY life is worth investigation

pelletbucket ,
@pelletbucket@lemm.ee avatar

that has nothing to do with why I asked that question lol. if you have to investigate every single one that shows signs of life, that would mean investigating a lot of worlds before you find any with intelligence.

HurlingDurling ,
@HurlingDurling@lemmy.world avatar

By the color of their hats /jk

pelletbucket ,
@pelletbucket@lemm.ee avatar

seriously though, I think life on other planets probably just usually evolves underground, so even if they develop some sort of intelligence they're not looking up at the sky so they have no motivation to explore beyond their atmosphere no matter how advanced they get.

there was a planet in The hitchhiker's Guide to the Galaxy universe that had thick cloud cover so that people never even conceived of an existence beyond their planet. when a spaceship crashed there, it never even occurred to them that it might have come from the sky

Maggoty ,

I think we're the first. Or rather in the first wave of intelligent life. It could take a thousand years just for a message to reach us. On the theory that life has evolved to this point as fast as possible over the life of our Galaxy, there's no filter. There just hasn't been enough time for contact to occur.

LordGimp ,

Time itself is the filter. I don't think we are the first, but I don't think we will every find any other intelligent life. The universe is too big and our lives are far too short to make any sort of attempt to travel or communicate across those distances ourselves. I'm also not entirely confident our idea of what a society is will last in any meaningful way over the timespans required. Our longest lasting dynasties rarely make it more than a couple hundred years. Space is just too big for us to work with using our current understanding of physics.

LordGimp ,

Pushing Ice by Alastair Reynolds is one of my favorite scifi books and it deals with this question in an interesting way. It proposes that Time is the great filter. Life exists in this galaxy, but intelligent life is so fleeting when considering galactic distances that the probability of one sentient lifeform finding another during their "peaks" is vanishingly small. Extinction, societal collapse, evolution to a higher form, whatever you want to imagine, it all gets in the way of the fantasy of meeting a thinking being from another planet.

Allero ,

I don't think there is a single universal Great filter, and living and then potentially sentient beings with various traits will face various obstacles.

First, life needs suitable materials for polymers and a lot of energy. Most places don't have both.

Next, basic blocks of life that would be self-replicating and adaptive should be randomly generated, which is extremely unlikely and literally took over a billion years on Earth, a planet with generally great conditions for such process.

Then, those blocks should be able to get together to form complex structures - ideally, many separate ones, so that one event wouldn't destroy the entire effort. Earth had it easy, with billions of super simple life forms.

Next, assuming life survived up to this point in a potentially unfriendly and ever-changing environment, bombarded by UV light and exposed to myriad of sources of damage, it should not destroy itself or environment too badly to never recover. Earth had periods when life generated too much carbon dioxide or too much oxygen (yes, that too was a thing), and those were critical points at which our story could very much end.

Then, life has to evolutionize and get into complex forms, either by forming multicellular organisms or by making a cell a powerhouse of everything.

Then, life has to get sentient, and some kind of response system should be available and get highly complex.

Then, most of the sentient creatures just won't be tribal, and civilization requires society and a common effort.

Then, many more won't be expansionist, and will die out in some small region.

Many also won't be competitive, which would slow down evolution.

For those species who are competitive, they shouldn't destroy each other while they're at it, and this is currently one of the risks of our own.

And after all that, they should develop space travel and either get as developed and decisive and resource-rich as to send a generational ship to some random planet named Earth populated by genocidal monkeys, or to somehow hyperdrive here. They can very much decide it's not worth it, and they may be so far away we couldn't see signs of their civilization.

theneverfox ,
@theneverfox@pawb.social avatar

I don't think life is rare, nor photosynthesis, but complex life might be. A planet needs to be really thriving with life for it to be worth it to go down the path to something like animals

But I think the bigger filter is much stranger.

Humans are a hive-like species. We're not just social - we're insanely interdependent, we don't function on our own and yet we've ended up in this place where we (often) try to individually succeed, even at the cost to our community

We're greedy enough to want the stars, yet interdependent enough we could only swarm over them in endless numbers

There's many problems with the fermi "paradox", but personally I think one of the largest is assuming all species would spread like a cancer blotting out the stars

A more individualistic and long lived species might instead be careful explorers, taking what they need and leaving little sign of their passage. A more communal species might be careful and control themselves to not destroy pointlessly. They might also feel no desire to contact other species

We're just the right mix to want everything a star could give, and to want to find others at great energy cost

Cryophilia OP ,

God help the universe if we ever discover FTL travel and escape the prison of lightspeed.

MintyFresh ,

I have a new religion!

Prometheus didn't gift us fire and cognition. Lies. We are Prometheus's curse on the universe. Nothing more than a plague on the gods creation, concocted for some slight we can never understand. The sum of us, brought into being, then tossed into the void and forgotten. To spread like an oil stain across creation.

Cryophilia OP ,

"And behold, I Myself am bringing floodwaters on the earth, to destroy from under heaven all flesh in which is the breath of life; everything that is on the earth shall die." - Genesis 6:7

"If you had not committed great sins, God would not have sent a punishment like me upon you." - Genghis Khan

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