Chapter 25 5.3 Maintaining balance in a persistent teetering state

Thirty years ago, biologists asked NASA (National Aeronautics and Space Administration) to send two unmanned probes to the two candidate planets most likely to find extraterrestrial life—Mars and Venus, And probes were inserted into their soil to detect signs of life. NASA's Life Detector is a complex, sophisticated and expensive contraption that, once it lands, looks for clues of bacterial life in the dust that falls on it.James Lovelock, a soft-spoken British biochemist, was one of the consultants hired by NASA.He discovered a way to better detect life on planets.The approach doesn't require multimillion-dollar contraptions, or even launch rockets.

Lovelock is a rare genius in the field of modern scientific research.He works like a loner in his scientific research in a stone warehouse surrounded by hedgerows in rural Cornwall, England.He maintains an impeccable scientific reputation, but he is not affiliated with any formal scientific research institution, which is rare in the scientific community that requires large sums of money at every turn.His stark independence nourishes and cannot be separated from free thought.In the early 1960s, Lovelock made a game-changing proposal that upset the rest of NASA's exploration team.They really wanted to send probes to extraterrestrials, but he said there was no need to bother.

Lovelock told them that he could determine whether a planet harbored life simply by looking through a telescope.He can determine the composition of its gases by measuring the spectrum of the planet's atmosphere.The composition of the atmosphere that surrounds a planet can reveal whether a planet has ever hosted life.So instead of throwing an expensive canister across the solar system to find out.He already knew the answer. In 1967, Lovelock wrote two papers predicting that, based on his interpretation of the spectrum of the planet's atmosphere, there would be no life on Mars.Ten years later, NASA launched an orbiting spacecraft around Mars. Ten years later, several spectacular Mars soft landing detections finally clearly told the world that Mars is indeed as lifeless as Lovelock predicted.Similar probes to Venus brought back the same bad news: the solar system is barren except for Earth.

How did Lovelock know? It is through the study of chemical reactions and co-evolution.The components in the Martian atmosphere and soil are energized by the sun's rays, heated by the Martian core, and then attracted by the Martian gravity, entering a dynamic equilibrium over millions of years.Knowing the general rules of chemical reactions, scientists can calculate the complex reactions of the planets as if they were substances in a large flask.After chemists came up with approximate reaction equations for Mars, Venus, and other planets, the two sides of the equal sign were basically equal: energy, ingested components; energy, outgassed components.The results obtained through astronomical telescopes and later on-site sampling all conform to the predictions of the response equation.

Earth is different.The number of paths that gases mix in Earth's atmosphere is irregular.Their anomalies, Lovelock has identified, are an interesting cumulative effect of coevolution. Taking oxygen as an example, it accounts for 21% of the earth's atmosphere, causing the instability of the earth's atmosphere.Oxygen is a highly reactive gas that combines with many elements in the intense chemical reaction we call fire or combustion.From a thermodynamic point of view, the high levels of oxygen in Earth's atmosphere should drop rapidly as the atmosphere oxidizes solid surfaces.Other reactive trace gases such as nitrous oxide and methyl iodide are also at unusually elevated levels.Oxygen and methane, though coexisting, are simply not compatible, or rather, they are so compatible that they would detonate each other.Inexplicably, carbon dioxide, which is supposed to be a major component of the atmosphere on other planets, is merely a tracer gas.In addition to the atmosphere, the temperature and alkalinity of the Earth's surface are also at unusual levels.The entire surface of the Earth appears to be one gigantic, unstable chemical variation.

It seemed to Lovelock that there was an invisible energy, an invisible hand, that pushed the chemistry of the interaction to a certain high point, only to drop back to equilibrium at any moment.The chemical reactions on Mars and Venus are as stable and lifeless as the periodic table of elements.Measured by the table of chemical elements, the chemistry of the earth is abnormal, completely out of balance, yet full of vitality.From this, Lovelock concluded that any planet that hosts life exhibits strangely unstable chemistry.A life-friendly atmosphere doesn't have to be oxygen-rich, but it should break the norm.

That invisible hand is co-evolving life. Coevolving life has a remarkable ability to generate stable non-steady states, pushing the chemical cycles of the Earth's atmosphere into what Lovelock calls "persistent disequilibrium."The amount of oxygen in the atmosphere should drop all the time, but it just doesn't drop for millions of years.Since the vast majority of microbial life requires high concentrations of oxygen, and since microbial fossils have existed for hundreds of millions of years, this strange state of discordant harmony can be regarded as quite long-lasting and stable.

Earth's atmosphere seeks a steady oxygen level much in the same way a thermostat seeks a steady temperature.It happened to produce an average oxygen concentration of 20 percent, "by pure chance," according to one scientist.Below this level is oxygen depleted, above this level it is flammable.George R. Williams of the University of Toronto writes: "Oxygen levels of around 20% seem to provide a balance of near-perfect circulation of ocean currents without incurring more toxic or combustible organic build-up. Great hazard.” So, where are the Earth’s sensors and temperature control mechanisms?Where is the stove for heating?

The lifeless planet achieves balance through geological cycles.A gas, such as carbon dioxide, dissolves into a liquid and precipitates out as a solid.Natural saturation is achieved after a certain amount of gas is dissolved.Solids are heated or pressurized during volcanic activity, releasing gases back into the atmosphere.Subsidence, weathering, uplift—all great geological forces—also break or synthesize the molecular chains of matter, as powerful chemical actions do.Thermodynamic entropy changes pull all chemical reactions to their lowest energy values.The imaginary furnace collapsed.The balance on the inanimate planet is not like the balance under constant temperature control, it is more like the water in the bowl, which is at the same level; when it cannot go lower, it is simply at the same level.

The earth is a thermostat.Intertwined and co-evolved life provides a self-circulating loop that directs Earth's chemistry toward rising potential energy.Presumably after all life on Earth dies out, Earth's atmosphere will fall back to a permanent equilibrium, becoming as drab as Mars and Venus.But as long as the distributed hand of life remains dominant, it can keep Earth's chemistry off the table. But the imbalance itself is self-balancing.The persistent imbalance produced by co-evolving life has its own way of stabilizing.Lovelock has been working to find the existence of this persistent imbalance.As far as we know, the oxygen content of about 20% in the earth's atmosphere has been maintained for hundreds of millions of years.The atmosphere wobbles like an acrobat on a high-altitude cable, and has held that position for millions of years.She never falls, and she can never escape the tendency of falling, always in a precarious state.

Lovelock considered this persistent state of teetering to be the defining characteristic of life.Recently researchers in complexity theory have also realized that any living system: economies, natural ecosystems, complex computer simulations, immune systems, and co-evolutionary systems, has the remarkable characteristic of being shaky.They all have that paradoxically optimal quality of being in an Escherian equilibrium—a state of always descending but never lowering—balanced in a slump. In his popular science book Cosmogenesis, David Razel argues that "the central value of life lies not in the immutability of its reproduction, but in the instability of its reproduction." The key to life lies in a slight Propagate out of balance, not in order.This almost falling and even chaotic operating state ensures the proliferation of life. A central feature of living systems that has received little attention is that this paradoxical quality is contagious.Living systems transmit their erratic posture to everything they touch, and nothing less.On Earth, life is rampant, expanding its power into solids, liquids and gases.As far as we know, there is no rock that has never been touched by life.Tiny marine microbes solidify carbon and oxygen dissolved in seawater, producing a salt that spreads across the sea floor.These deposits are eventually pressed into rock by the weight of sedimentation.Tiny plant-based microbes suck carbon from the air into the soil and down to the seafloor, where it turns into oil underwater.Life produces methane, ammonia, oxygen, hydrogen, carbon dioxide, and other gases.Iron - and metal-enriching bacteria create metal ore clusters. (Iron is the poster child for non-life, which was produced by life!) Through rigorous observation, geologists concluded that all outcropping rocks (except perhaps volcanic rocks) are recycled sediments, so all rocks are Biogenic in substance, that is, influenced in some way by life.The relentless push and pull of co-evolving life ultimately brings the non-living matter of the universe into its game.It turns even the stubborn stone into a part of its reflection.