Life on the third planet eight light minutes from our sun - Earth, that is - teeters on a biological seesaw. If our orbit shifted a tiny fraction toward or away from the sun, most life forms would perish in a fire or ice world.
The most wondrous thing in this balance, which we daily take for granted, is how did life and the processes of life originate on Earth. Was it supernaturally created, spontaneous or seeded or even transplanted from other inhabited planets? Astronomer Carl Sagan in his book Cosmos calculates that in our Milky Way galaxy alone multi-cellular life forms could arise on 100 billion planets and very advanced reasoning beings gestate on millions of worlds.
Up till the 1980's, the prevailing scientific theory of life-origins was the spontaneous one: organic (carbon-based) molecules bubbling up out of the 3.5 billion year-old 'primeval soup' to slowly combine into evermore complex, self-reproducing cellular units. The spontaneous soup theory is now down the drain, primarily because atmospheric scientists have concluded that key ingredients for molecular life-methane and pure carbon-in Earth's primal atmosphere were missing from the recipe.
Interstellar space and comets are now perceived as Earth's nursery room and cradle. Space-surveying researchers have discovered over the past two decades molecules ranging from water to a herd of organic compounds including grain alcohol and complex ring-type carbon chains. Amino acids-the building blocks of proteins-are expected to be detected any time. NASA's Scott Sandford says "Now there's no doubt that the amino acids are extraterrestrial" and "when the solar system was forming, it was already seeded with lots of complex molecules of biogenic interest." Two astronomers, Fred Hoyle and Chandra Wickramasinghe, seriously postulate that disease bacterium and viruses came from space, and that life is older than our solar system - a conviction Hindus would certainly agree with. Incredible to the scientists, but not surprising to Hindu theologians, huge interstellar dust clouds billowing out into cold space are swarming with the stuff of life, and comets were/are ferrying these compounds to planets like giant supertankers.
In 1986 when Halley's comet streaked through our orbital plane, two remote probes rendezvoused with it. Their sensors picked up some startling data: Halley's was 20% organic matter. That is enough to match 10% of Earth's total biological mass. It also carried polymers, large groups of molecules bound together. Estimates state that all of our solar system's comets' combined organic mass would equal that of 10,000 Earths at our present biomass: the total measure of living matter. Life is not scarce. Indeed it is cosmically decreed.