Silicon based life?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Dinosaur, Sep 10, 2017.

  1. Dinosaur Rational Skeptic Valued Senior Member

    A common SciFi concept, but does not seem reasonable in reality.

    While silicon has the same valence properties as carbon, many of its compounds are solids while the corresponding carbon compounds are gases or liquids except at high temperatures.

    Solids do not provide the mobility for life forms capable of evolving to development of of a technological culture. I also suspect that a brain requires more rapid chemical reactions than provided by most silicon compounds.

    Solids cannot be the basis for a flexible hand (or other type of appendage) capable of picking up a stick or stone for use as a weapon or tool is a necessary precursor to the evolution of a creature which can develop a technological culture.​
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  3. exchemist Valued Senior Member

    Yes indeed. The polysilanes are liquids but the problem, I think, is that Si easily forms strong bonds to oxygen AND can "expand its octet" to form >4 bonds, which carbon does not readily do. So it is hard to stop Si from being grabbed by oxygen, if there is any around, which will disrupt any silane chains. And so you end up with wet sand! I suppose one might find Si based life in an environment with no oxygen, but this element is very prevalent in the cosmos as its synthesis is a feature of later stage stars.
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  5. Dinosaur Rational Skeptic Valued Senior Member

    ExChemist: Thanx for your reply.

    I started this Thread due to a speculative article in a special issue of Popular Science which discussed silicon based life. I consider SciAm more reliable than Popular Science & was not sure how much credence to give it the Popular Science article.

    My scientific education & subsequent reading relates primarily to mathematics & secondarily to physics/engineering. My background in chemistry consists of a only one college course & the reading of some essays from folks like Asimov.

    You provide some support for my negative notions relating to silicon based life.

    BTW: Asimov SciFi was my first introduction to him. Due to his essays on history, I became interested in history several years after graduating from college. Until his essays, I took a few history courses only due to their being required in both high school & college.
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  7. timojin Valued Senior Member

    I heard that about 40 years ago and it was discarded

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