One of the links we used in the outro of "European Water Technology Startups".
From Cosmic Search, the magazine of the North American AstroPhysical Observatory (NAAPO), Volume 3 Number 1; Winter 1981:
Not as We Know it
The Chemistry of Life
By: Isaac Asimov
Even unpleasant experiences can be inspiring.
For instance, my children once conned me into taking them to a monster-movie they had seen advertised on TV. "It's science fiction," they explained. They don't exactly know what science fiction is, but they have gathered it's something daddy writes, so the argument is considered very powerful.
I tried to explain that it wasn't science fiction by my definition, but although I had logic on my side, they had decibels on theirs.
So I joined a two-block line consisting of every kid for miles around with an occasional grown-up who spent his time miserably pretending he was waiting for a bus and would leave momentarily. It was a typical early spring day in New England — nasty drizzle whipped into needle-spray by a howling east wind — and we inched slowly forward.
Finally, when we were within six feet of the ticket-sellers and I, personally, within six inches of pneumonia, my guardian angel smiled and I had my narrow escape. They hung up the SOLD OUT sign.
I said, with a merry laugh, "Oh, what a dirty shame," and drove my howling indignant children home. Anyway, it got me to thinking about the lack of imagination in movieland's monsters. Their only attributes are their bigness and destructiveness. They include big apes, big octopuses (or is the word "octopodes"?), big eagles, big spiders, big amoebae. In a way, that is all Hollywood needs, I suppose. This alone suffices to drag in huge crowds of vociferous human larvae, for to be big and destructive is the secret dream of every red-blooded little boy and girl in the world.
What, however, is mere size to the true aficionado? What we want is real variety. When the cautious astronomer speaks of life on other worlds with the qualification "life-as-we-know-it," we become impatient. What about life-not-as-we-know-it?
Well, that's what I want to discuss.
To begin with, we have to decide what life-as-we-know-it, means. Certainly life-as-we-know-it is infinitely various. It flies, runs, leaps, crawls, walks, hops, swims, and just sits. It is green, red, yellow, pink, dead white and vari-colored. It glows and does not glow, eats and does not eat. It is boned, shelled, plated and soft; has limbs, tentacles or no appendages at all; it is hairy, scaly, feathery, leafy, spiny and bare.
If we're going to lump it all as life-as-we-know-it, we'll have to find out something it all has in common. We might say it is all composed of cells, except that this is not so. The virus, an important life form to anyone who has ever had a cold, is not.
So we must strike beyond physiology and reach into chemistry, saying that all life is made up of a directing set of nucleic acid molecules which controls chemical reactions through the agency of proteins working in a watery medium.
There is more, almost infinitely more, to the details of life, but I am trying to strip it to a basic minimum. For life-as-we-know-it, water is the indispensable background against which the drama is played out, and nucleic acids and proteins are the featured players.
Hence any scientist, in evaluating the life possibilities on any particular world, instantly dismisses said world if it lacks water; or if it possesses water outside the liquid range, in the form of ice only or of steam only.
(You might wonder, by the way, why I don't include oxygen as a basic essential. I don't because it isn't. To be sure, it is the substance most characteristically involved in the mechanics by which most life forms evolve energy, but it is not invariably involved. There are tissues in our body that can live temporarily in the absence of molecular oxygen, and there are microorganisms that can live indefinitely in the absence of oxygen. Life on earth almost certainly developed in an oxygen-free atmosphere, and even today there are microorganisms that can live only in the absence of oxygen. No known life form on earth, however, can live in the complete absence of water, or fails to contain both protein and nucleic acid.)
In order to discuss life-not-as-we-know-it, let's change either the background or the feature players. Background first!
Water is an amazing substance with a whole set of unusual properties which are ideal for life-as-we-know-it. So well fitted for life is it, in fact, that some people have seen in the nature of water a sure sign of Divine providence. This, however, is a false argument, since life has evolved to fit the watery medium in which it developed. Life fits water, rather than the reverse.
Can we imagine life evolving to fit some other liquid, then, one perhaps not too different from water? The obvious candidate is ammonia....
....MUCH MORE
