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.

  • @CryophiliaOP
    10•4 months ago

    Honorable mention: we haven’t detected alien probes, because intelligent alien societies haven’t begun consuming the galaxy with exponential numbers of self-replicating robotic probes, because that’s just a really bad idea:

    Simple workarounds exist to avoid the over-replication scenario. Radio transmitters, or other means of wireless communication, could be used by probes programmed not to replicate beyond a certain density (such as five probes per cubic parsec) or arbitrary limit (such as ten million within one century), analogous to the Hayflick limit in cell reproduction. One problem with this defence against uncontrolled replication is that it would only require a single probe to malfunction and begin unrestricted reproduction for the entire approach to fail – essentially a technological cancer – unless each probe also has the ability to detect such malfunction in its neighbours and implements a seek and destroy protocol (which in turn could lead to probe-on-probe space wars if faulty probes first managed to multiply to high numbers before they were found by sound ones, which could then well have programming to replicate to matching numbers so as to manage the infestation).

    • @[email protected]
      4•4 months ago

      Oh my god, that’s such a stupid and simple way to kill a galaxy, but also what a great plot twist that would make in a story. Like the big reveal over why the galaxy has always been at war with itself. Exactly the kind of nihilism I’d expect from an Altered Carbon or its ilk.

      Thanks for sharing!

    • @[email protected]
      1•4 months ago

      There’s an easier and more reliable way to limit replication; don’t hive them the means to create a small but essential part, and instead load the first probe woth many copies of it and have each replica take a set percentage.

      For instance, have the probe able to replicate everything but its CPU, and just load up a rack of them on probe 0. Every time it replicates itself it passes half of its remaining stock to the replica and they both carry on from there.