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Thread: What do you think is the most likely explanation for the Fermi paradox?

  1. #811
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    Quote Originally Posted by Roger E. Moore View Post
    A new paper on the Great Filter.

    https://arxiv.org/abs/2002.08776

    Observational Constraints on the Great Filter
    Jacob Haqq-Misra, Ravi Kumar Kopparapu, Edward Schwieterman
    (Submitted on 18 Feb 2020)

    The search for spectroscopic biosignatures with the next-generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life. An extension of this spectroscopic characterization of exoplanets is the search for observational evidence of technology, known as technosignatures. Current mission concepts that would observe biosignatures from ultraviolet to near-infrared wavelengths could place upper limits on the fraction of planets in the galaxy that host life, although such missions tend to have relatively limited capabilities of constraining the prevalence of technosignatures at mid-infrared wavelengths. Yet search-ing for technosignatures alongside biosignatures would provide important knowledge about the future of our civilization. If planets with technosignatures are abundant, then we can increase our confidence that the hardest step in planetary evolution--the Great Filter--is probably in our past. But if we find that life is commonplace while technosignatures are absent, then this would in-crease the likelihood that the Great Filter awaits to challenge us in the future.
    IOW We're still extrapolating from a sample size of one, but now we can be more pessimistic about it!

    No, if we find find (a BIG if) life is common and easily detectable tech isn't, it only means that life is common while easily detectable tech isn't.

    Perhaps it just means life does not always produce the kind of intelligent tool use leading to interstellar-ly visible Dyson spheres "technosignatures at mid-infrared wavelengths", and that's the whole "Great Filter" maybe possibly?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  2. #812
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    Quote Originally Posted by Roger E. Moore View Post
    A paper is out that says "life in the universe could be common, but not in our neighborhood". Now, what they mean by "our neighborhood" is the entire observable universe. WHAT? So we're essentially alone, you're saying?

    https://phys.org/news/2020-03-reveal...ghborhood.html

    "RNA is a polymer, meaning it is made of chemical chains, in this case known as nucleotides. Researchers in this field have reason to believe that RNA no less than 40 to 100 nucleotides long is necessary for the self-replicating behavior required for life to exist. Given sufficient time, nucleotides can spontaneously connect to form RNA given the right chemical conditions. But current estimates suggest that magic number of 40 to 100 nucleotides should not have been possible in the volume of space we consider the observable universe.... Indeed, the observable universe contains about 10 sextillion (10^22) stars. Statistically speaking, the matter in such a volume should only be able to produce RNA of about 20 nucleotides. But it's calculated that, thanks to rapid inflation, the universe may contain more than 1 googol (10^100) stars, and if this is the case then more complex, life-sustaining RNA structures are more than just probable, they're practically inevitable."
    As Van Rijn said, they're leaving out any intermediate steps between randomness and fully formed biochemistry.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  3. #813
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    Quote Originally Posted by Noclevername View Post
    As Van Rijn said, they're leaving out any intermediate steps between randomness and fully formed biochemistry.

    also leaving out the effect of evolution (it sounds like a creationist argument that life is virtually impossible).

  4. #814
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    Quote Originally Posted by Noclevername View Post
    As Van Rijn said, they're leaving out any intermediate steps between randomness and fully formed biochemistry.
    See, I think you've got a point as there's this article and others talking about RNA evolving, essentially.

    https://www.newscientist.com/article...lop-into-life/
    Do good work. —Virgil Ivan "Gus" Grissom

  5. #815
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    Quote Originally Posted by Roger E. Moore View Post
    See, I think you've got a point as there's this article and others talking about RNA evolving, essentially.

    https://www.newscientist.com/article...lop-into-life/
    Self-assembly is a noted property of many complex molecular patterns.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  6. #816
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    My favorite analogy is the box of paperclips. Shaken up, the clips will usually hook on to each other and form long complex branching chains. A good example of adding energy to a chaotic system and getting order out of randomness.

    I think comparing self-organizing organic chemistry and biogenesis to winning a lottery is a misleading analogy. One in a million chance of winning, but if you have a billion players playing a million times each, the odds of no one winning at all are vanishingly small.

    The scale in time and places of the trial and error mixing and matching of molecules on early Earth, means that lots and lots of one in a billion chances actually happened. I'm not saying self replicating molecules were inevitable, just that in some form or another, they were probably not as unlikely as one event.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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