The biochemistry of life in this universe is pretty much a given constant. The bonds that hold things together and the mechanisms that replicate molecules are governed by a chemistry and physics that have known physical limits. Get things too salty, too acid or too alkaline and this chemistry can't hang together. It's a fact of life.

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Anything may be possible, but not everything actually is. Some things are true and some things are not. Wisdom is knowing the difference.