Why is liquid water what is "required" for life?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Mr. Hamtastic, Sep 1, 2008.

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  1. halo07guy

    halo07guy Registered Senior Member

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    400
    I am reminded of a famous qoute. I believe it was something along the lines of: "He believed that all life must be composed of water and carbon and metabolized free oxygen because he was composed of water and carbon and metabolized free oxygen".

    Currently, its accepted in the scientific community that any number of other materials could replace water as a solvent. Liquid methane very well could. It doesn't have to be carbon-based life, either. It could be any number of other elements, such as yttrium. You have to remember that we only have ONE example of life in an entire universe. Saying that all life in the universe must be composed of similar elements to the lifeforms that are on a tiny little rock in a corner of a galaxy is more then a little foolish. We only made up of this because:
    A. Most common elemnts in the area.
    B. The location of Earth.
    C. The size of our sun.

    There are way too many variables that can affect it. What seems like paradise to us could likely be a hellhole for another species.
     
    halo07guy, Sep 2, 2008
    #21

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  3. Yorda

    Yorda Registered Senior Member

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    i think you need 4 things for life: water, earth, air and fire (star). you probably also need a fifth thing (spirit, ether).
     
    Yorda, Sep 3, 2008
    #22

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  5. Ophiolite

    Ophiolite Valued Senior Member

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    9,232
    No it isn't. It is accepted by some interested scientists, but by no means all interested scientists, that a small number of other substances could replace water as a solvent. Those caveats result in a quite different scenario for the possibility of life.
    Wrong again. The phrase 'any number' refers to a large number, to a large proportion of available options. It implies, in this context a half or a third of the elements could serve the role of carbon. I hope you agree that is pure nonsense.

    Please provide a source for your claim that yttrium is one of these possiblities.
    Wrong again. The elements we are composed of constitute some of the most commone elements throughout the universe.


    F-



    You need an education.
     
    Ophiolite, Sep 3, 2008
    #23

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  7. eburacum45

    eburacum45 Valued Senior Member

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    I reccomend this book, which can be read online here: The Limits of Organic Life in Planetary Systems

    here is a taster, a table of possible solvents comparing their liquid temperature ranges

    Solvent:::::Freezing Point (K)::::::Boiling Point (K)

    Ammonia:::::::195::::::::::::::::::::::240

    Dihydrogen:::::14::::::::::::::::::::::::20

    Dinitrogen::::::63::::::::::::::::::::::::77

    Ethane::::::::101::::::::::::::::::::::::184

    Formamide::::273:::::::::::::::::::::::495

    Helium:::::::::nil::::::::::::::::::::::::::4

    Hydrazine:::::275:::::::::::::::::::::::387

    Hydrogen:::::260::::::::::::::::::::::::299
    cyanide

    Hydrogen:::::190::::::::::::::::::::::::293
    fluoride

    Hydrogen:::::192::::::::::::::::::::::::213
    sulphide

    Methane::::::91::::::::::::::::::::::::::112

    Neon::::::::::25::::::::::::::::::::::::::27

    Sulphuric:::::283::::::::::::::::::::::::563
    acid

    Water::::::::273:::::::::::::::::::::::::373
     
    Last edited: Sep 3, 2008
    eburacum45, Sep 3, 2008
    #24
  8. Fraggle Rocker

    Fraggle Rocker Staff Member

    Messages:
    24,690
    When we say liquid water is required for life, we mean life as we know it. We'll probably have a hard time recognizing a different sort of life when we encounter it. We could zoom right past it. But to answer the question, obviously the reason life as we know it evolved here is that it evolved in response to its environment. In a different environment, life would evolve differently if it happened to arise.
    Well, water is a unique compound, whose many unique properties facilitate the biological processes we're familiar with. And water is a common substance throughout the universe since it's made of extremely common elements. (Astrophysicists, am I right about that?) So it's a reasonable assumption that we'll find life using some of the same processes we're familiar with, in environments with the right chemistry, temperature and pressure. Obviously not in a gas giant, on a boiling-hot planet like Venus, or out in interstellar space.

    A number of sci-fi writers are professional scientists and go to great lengths to hypothesize alien life that is scientifically plausible without being a coincidental duplicate of Earth's biochemistry. James P. Hogan and Robert L. Forward, two of my favorite authors, are famous for that. Hogan invented a biology based on nuclear reaction, and Forward built one on a neutron star. Although they also write stories about vaguely earthlike life on vaguely earthlike planets, just because it's a lot easier to imagine us discovering each other.
     
    Fraggle Rocker, Sep 3, 2008
    #25
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