James Lovelock provides a compilation of scientific definitions of Life in the glossary of his book The Vanishing Face of Gaia(Basic Books, 2009). I’ve taken the liberty of including it here.
Life. Life exists simultaneously but separately in the realms of physics, chemistry, and biology and consequently has no decent scientific definition. Physicists might define it as something that exists within bounds, that spontaneously reduces its entropy (disorder) while excreting disorder to the environment. Chemists would say that it is composed of macromolecules coming mainly from the elements carbon, nitrogen, oxygen, hydrogen, and lesser but required proportions of sulphur, phosphorus, and iron, together with a suite of trace elements that includes selenium, iodine, cobalt, and others. Biochemists and physiologists would see life as always existing within cellular boundaries that hold an aqueous environment with a tightly regulated composition of ionic species, including the elements sodium, potassium, calcium, magnesium, and chlorine. Each of the cells carries a complete specification and instruction set written as a code on long, linear molecules of deoxyribonucleic acids (DNA). Biologists would define it as a dynamic state of matter that can replicate itself; the individual components will evolve by natural selection. Life can be observed, dissected, and analyzed but it is an emergent phenomenon and may never be capable of rational explanation.
A more right-brained person might consider Life as being the burst of creativity which enlivens each individual—and simultaneously all of humanity. Life can be thought of as the sojourn each individual has to create something new in our observable universe—be it progeny, art, scientific discovery, and community; or avarice, genocide, vice, and self-indulgence. Every being now alive--and that has ever lived--contributes their unique fingerprint as a legacy to subsequent life.
Life, as Lovelock says, may never be capable of rational explanation, but perhaps we’re wise to responsibly consider our form of creative expression--the fingerprint we leave behind.
