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.

  • LordGimp@lemm.ee
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    7 days ago

    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.

  • HurkieDrubman@lemm.ee
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    7 days ago

    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

  • HANN@sh.itjust.works
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    7 days ago

    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.

  • Anyolduser@lemmynsfw.com
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    8 days ago

    Boy, Lemmy sucks donkey dick. For every one legitimate answer there are two or three edgelord answers like “capitalism” and “the internet”.

    Here’s an answer that hasn’t come up yet: cooperation among mono cellular organisms. I don’t mean the development of polyp analogues or colonies of single celled organisms; I mean getting down to mitochondria. Brace for wild oversimplification.

    Before mitochondria, life had a hard time creating enough energy to do much more than barely stay alive. The current line of thinking is that one organism ate another and didn’t digest it. The two organisms worked symbiotically, one handled energy production and the other handled getting food and staying alive.

    Just about every living thing utilizes mitochondria and if the current idea that mitochondria were actually symbiotic organisms is true, that means that what was likely a chance “sparing” of prey is the underpinning of all complex life.

    The odds of that happening are ridiculously low. There could be simple life in tons of places even within our own tar system, but if the mitochondria-like symbiotic capture never happens for those extraterrestrial organisms, then complex life is probably unlikely to develop.

    • Gregonar@lemmy.world
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      8 days ago

      Maybe cooperation is hard wired just like competition. It might be less likely but hardly impossible.

      • Anyolduser@lemmynsfw.com
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        7 days ago

        I’d hardly describe it that way. It took untold trillions of predator/prey interactions over the hundreds of millions of years that single celled life existed for it to happen. That’s more or less brute forcing the problem and it took geologic timescales to happen.

        If you ask me to point at a hurdle stopping civilizations from developing that looks awfully reasonable.

        • Gregonar@lemmy.world
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          7 days ago

          Ultimately we don’t know much about that era of time, but I suspect it was less like fumbling around for millions of years looking for a light switch, and more like the gradual warming of the planet with warmer and cooler seasons/years.

          Iirc at least one of the other things related to development of eukaryotes was that atmospheric oxygen had to first be generated by early cyanobacteria.

          So maybe that proverbial light switch was being flipped millions of times through random encounters but only became more viable after the voltage (atmospheric oxygen levels) became high enough. Maybe that’s the reason it took hundreds of millions of years, because transforming by bacteria just takes that long.

          We just don’t know unfortunately. However, we DO know about species getting wiped out by asteroids or human cultures getting wiped out by disease or conflict with superior cultures. Any of these filters seems more of a hurdle to me than the development of eukaryotes.

    • HurkieDrubman@lemm.ee
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      7 days ago

      your paragraphs complaining about it are a lot more annoying than the people who might not be being totally serious on the internet for a minute.

      • Anyolduser@lemmynsfw.com
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        7 days ago

        If by “paragraphs” you mean two sentences, sure.

        If you’d bothered to read past those two sentences you’d see that I was making an offhand comment before answering the question.

  • Foni@lemm.ee
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    8 days ago

    Energy needed to leave your planetary system vs energy available on your planet of origin.

    We have not yet overcome it and I am not sure that we will achieve it.

    • Cryophilia@lemmy.worldOP
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      8 days ago

      Well, we’ve already sent a couple of probes out of the solar system, but they’re not really going fast enough to have any meaningful interstellar impact.

  • oo1@lemmings.world
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    8 days ago

    I think most lifeforms will have more pressing matters than wasting large amounts of time an energy blasting signals in to space for no reason, or listening to the sky.

    Maybe those civilizations that waste more energy chasing aliens die off sooner due to wasting resources on sci-fi bullshit and ignoring their real problems at home.

    • Cryophilia@lemmy.worldOP
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      7 days ago

      I disagree. I think there is no more important thing we have ever done or will ever do as a civilization, than try to make contact with alien life.

      • VeganPizza69 Ⓥ@lemmy.world
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        7 days ago

        I think that it’s you who should read more.

        Here:

        Characteristic processes of human evolution caused the Anthropocene and may obstruct its global solutions | Philosophical Transactions of the Royal Society B: Biological Sciences

        We propose that the global environmental crises of the Anthropocene are the outcome of a ratcheting process in long-term human evolution which has favoured groups of increased size and greater environmental exploitation. To explore this hypothesis, we review the changes in the human ecological niche. Evidence indicates the growth of the human niche has been facilitated by group-level cultural traits for environmental control. Following this logic, sustaining the biosphere under intense human use will probably require global cultural traits, including legal and technical systems. We investigate the conditions for the evolution of global cultural traits. We estimate that our species does not exhibit adequate population structure to evolve these traits. Our analysis suggests that characteristic patterns of human group-level cultural evolution created the Anthropocene and will work against global collective solutions to the environmental challenges it poses. We illustrate the implications of this theory with alternative evolutionary paths for humanity. We conclude that our species must alter longstanding patterns of cultural evolution to avoid environmental disaster and escalating between-group competition. We propose an applied research and policy programme with the goal of avoiding these outcomes.

        Figure 2. Dimensions of environmental management create an attractor landscape for long-term human evolution. Environmental sustainability challenges (curved frontiers) require a minimum level of cooperation in a society of a certain minimum spatial size. Alternative potential paths move humanity toward different long-term evolutionary outcomes. In path B, competition between societies over common environmental resources creates cultural selection between groups for increasingly direct competition and conflict. Path A, growing cooperation between societies facilitates the emergence of global cultural traits to preserve shared environmental benefits.

  • randon31415@lemmy.world
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    8 days ago

    Everyone is talking about society or physiology stuff. That is just things that might get humans.

    Stars going super-nova is the real great filter. Our sun is 4.6 billion years old. Life started 4 billion years ago. In 4 billion years, the sun goes supernova. We are halfway to the end of the earth.

    Smaller stars last longer, but have smaller ranges that life can exist in - and planets tend to move in or out in their orbits. Bigger stars have giant habitable zones - but some large stars born when humans took their first steps are in their last decades of life. You couldn’t get from the pyramids to NASA in that time, never mind the 4 billion years it took to get to humans.

    • Pulptastic@midwest.social
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      8 days ago

      That is an interesting idea that is not typically considered in the drake equation as far as I know. That could significantly reduce the chance of finding intelligent life elsewhere.

      • oo1@lemmings.world
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        8 days ago

        I think it is in the drake equation effectively, it factors into the length of time that the civilization might send and receive detectable signals - It doesn’t say why the Civilisation might collapse, but the planet becoming uninhabitable is surely one reason. On wikipedia for Drake Equation the Carl Sagan specification of L is in terms of the “fraction of planetary lifetime”.

        I think a missing factor might be how directional transmission and receiving is, if we can’t broadcast to and listen to the whole sky equally then we might have a 1/r-cubed type issue with the chances of both listening and transmitting with enough strength/energy at the same time.

    • WhaleSnail@lemmy.world
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      8 days ago

      I think it’s supposed to actually less than that, the sun’s luminescence will increase over the next 1 billion years to the point that it will boil off the earth’s oceans. No life will be able to exist past that, and earth will just be a barren rock in orbit for the next 3 billion years.

  • sp3tr4l@lemmy.zip
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    8 days ago

    Howabout a reasonably advanced civilization destroying itself and its homeworld after exploiting and then running out of petroleum?

    • Subverb@lemmy.world
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      8 days ago

      Oil has a bad reputation but how lucky we are to have it. How does a civilization on a planet without hydrocarbons make the leap to a technological species?

      It’s not impossible, but it’s got to be a lot harder.

      • Tlaloc_Temporal@lemmy.ca
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        8 days ago

        Kelp farms? Domesticated bamboo? We need large areas of land to grow food anyway, we just skipped the charcoal agriculture step. Lathes and the three plate method are the real heroes of industry any way.

        A slower ascension into the computing age could mean a more stable set of cultures and a more uniform global situation to avoid anthropogenic filters. Bright candles and all that.

    • Seasoned_Greetings@lemm.ee
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      8 days ago

      I think it’s a fair thought that any form of life doesn’t perfectly recycle their resources and all forms of life give off waste for other life to utilize. That said, a reasonably advanced civilization might just inevitably grow to the size where the waste they put off makes their planet unlivable for them before they can take action to control it.

      For us, it’s carbon dioxide.

  • rottingleaf@lemmy.zip
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    8 days ago

    It’s a society (or the whole humanity) becoming big enough to survive even when ignorant murderers are the elite and the majority of it, and civilized people - a smaller part and almost a property, similar to animals in a zoo.

    When such a point is reached, the former will make the transition, and the latter will diminish over time. Then it just has no future.

    A bit like with Ottoman empire and Qajar Iran, only on the scale of the whole humanity there won’t be someone else to buy weapons and technologies from to keep going. Then some of the previously passable filters will kick in. Like hunger or resource scarcity.

  • averagechemist@lemmy.world
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    8 days ago

    Space itself. I believe there are other intelligent life forms out there and some of those happen to be close enough to communicate to each other/discover each other. We just hit the unlucky(or lucky) spot that we are simply too far away.

  • littlecolt@lemm.ee
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    8 days ago

    I would say it’s the size of the universe and the fact that it is still expanding at an accelerated rate.

    If the speed of light is really the “top speed” of the universe, it is inadequate for interstellar travel. It is barely good enough for timely communication, and not really even that.

    Life can be as likely as it wants to be, but it seems to me that we’re all quite divided, to the point of not being able to communicate at all with other potential intelligent species.