Alan Stahler: Looking at — and for — life
Special to The Union
Rain falls on a mountaintop, then flows to where it would “rather” be: downhill.
Water flowing downhill carries energy — energy we could harness with a water wheel.
Iron + wet weather = rust. Atoms of iron and oxygen, molecules of water, “feel” each other nearby. They would “rather” be glued together, iron to oxygen and water.
Rust is “downhill” from unglued iron and oxygen and water.
Rusting — going “downhill” — releases heat energy; rail cars of mill scraps (iron dust, filings, chips), exposed to the weather, have been known to catch fire.
Hot soup loses heat and grows cold. Heat energy would “rather” flow from something hot to someplace cold. Cold is “downhill” from hot.
Atoms in wood, bonding with atoms of oxygen in a woodstove, go “downhill,” and release heat; uranium nuclei, splitting in a reactor, go “downhill,” and release energy; small atomic nuclei, bonding into larger nuclei in the heart of the sun, go “downhill” and release sunshine. Everywhere we look, we see a universe going “downhill.”
With one exception: On one planet, circling one star, the “downhill” slide has been reversed.
That one planet is Earth, where life claws its way up.
Can life defy the “downhill” flow of the entire universe? Of course not. Life does not avoid the “downhill” slide; life exploits it.
When things go “downhill,” energy comes out. To make things go “uphill” — a hiker carrying water upward, a tree adding wood to its trunk, a cook warming a pot of soup – energy must be pumped in.
To go “uphill,” life harnesses the energy evolved as the rest of the universe slides down.
To keep warm, we build a fire. Atoms in wood are glued together in large molecules. They go “downhill” — and release energy — as they re-combine into smaller molecules of carbon dioxide and water.
To keep ourselves alive, we “burn” our food, re-combining its atoms, harnessing the energy they release as they slide “downhill.”
We “burn” our food; notice the quotes around “burn.” Setting fire to (dry) food would, indeed, release energy, but too much, too fast.
So, rather than glue food atoms to oxygen in a few short steps — releasing a lot of energy, all at once — we shepherd the atoms through a series of smaller steps, yielding a small amount of energy from some of those steps. That’s what’s special about life; everything is carefully managed.
Life shepherds atoms, controls energy — keeps us alive — with tiny-but-complex machines, built from hundreds, of atoms. These machines — and the bodies they construct — are far, far “uphill” of where their atoms would “rather” be, glued together in small molecules of water and carbon dioxide. The universe — and competing life-forms (predators and parasites) — are continually trying to drag down these magnificent, “uphill” structures. Life is a never-ending battle to repair and replace them.
Could life have evolved elsewhere — on other worlds in our solar system, on worlds circling other stars?
At 7 p.m. Wednesday at the Madelyn Helling Library, I’ll present a slide show on astrobiology: How life may have evolved on Earth, how it may have evolved elsewhere, how we’re searching for it.
Hosted by Nevada County Astronomers, it’s free, and all ages are welcome.
Al Stahler’s science programs can be heard on KVMR (89.5 FM). He brings an understanding of science and nature to students of all ages, and may be reached at email@example.com.
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