The Mathematics of the Earth

Home
I watched the documentary "Home", which I found on YouTube. The initial scenes portray the balance of the planet before agriculture and the remainder discusses what happened thereafter.

I think of the planet as a massively intricate dynamic system. The physics of everything that happens on Earth is incomprehensibly complex. The atmosphere, volcanic forces, the water cycle and countless other systems interact in non-linear fashion. The Earth is one big system and it changes towards equilibria points. Consider what I mean by equilibrium point: if the rest of the universe were to vanish and the Earth were to be utterly alone without the Sun or any other source of external energy, the Earth would perhaps become a cold, dark, lifeless hulk drifting through a void. The Earth's energy would tend to escape its grasp, and disperse itself evenly across space. Energy is always fair -- it spreads itself out as equally as possible. Maybe this is one of Earth's plural of  but it is not an interesting case because we are giving the Earth a big zero -- no energy in from its surroundings. The Sun is not dead yet, so this is not an interesting case right now.

The Push of the Sun
The Sun drapes the Earth in energy from its furnace of nuclear fusion and sets the dynamic system in motion. The Sun is like a boy pushing a cart. The boy gives a big push and the cart moves quickly until friction has sucked its energy away and it grinds to a halt. The Sun fuels the Earth as the boy fuels the cart. If the universe were only the Earth and the Sun, the Earth would eternally orbit and the Sun would heat the Earth and push its systems to some equilibrium. The energy patterns create the equilibrium of the climate and the seasons are due to the Earth's tilt. All of these things are cycles: the Sun cycles in intensity and weather on Earth is chaotic over a short-period of time, but in general, the Earth is a very stable place in this scenario. I think this is how the Earth would be if it were not for life. Earth might be stable with the occasional volcano or storm raging here and there, but these would constitute no more than noise in the history of the Earth.

The Control of Life
If the system of the Earth is stable by nature, then perhaps life is its controller. Perhaps life can drive the planet to instability or to other equilibria which would otherwise be unreachable. Consider the impact of algae and their predecessors. They have completely changed the composition of the atmosphere and the climate of the Earth itself. I think life is a powerful feedback system which controls the Earth. Life is capable of taking the noisiness of the state of the Earth and shoving it off kilter. If tiny fluctuations in the climate of the Earth allow life to grow and evolve in one direction rather than another, this is like an inverted pendulum being nudged to one direction.

Early Earth had much carbon-dioxide in the atmosphere which allowed life to evolve to exploit this detail. Algae breathed the carbon-dioxide and emitted oxygen in its place. As more oxygen became available, life evolved to breathe that too. Animals breathe oxygen and emit carbon-dioxide. Thus the cycle of plants and animal respiration created itself out of the noise of the Earth. This is a grand simplification, but it is important to see how life pushed the atmospheric trend in a completely new direction.

Are Humans a Controller Capable of Instability?
If life can change the planet, then certainly we can too, being alive. The only matter is the speed of change. It took millions of years for countless algae cells to change the atmosphere of the planet. Now we are changing the planet in drastic ways too, but the only novelty is the speed with which we are doing it. If the Earth is a delicate inverted pendulum, and life pushes upon it, can it push too hard? If the cart in the picture tries to drive too quickly, the drink will certainly spill, but it is possible to move forward very slowly. Perhaps life has always moved slowly and so the Earth remained relatively stable and the drink did not spill. There have been instances in the past where life has "spilled" from changing too quickly, but we are unsure as to most of there causes. The Middle Miocene disruption, for example, may have been caused by an asteroid impact, or otherwise, -- an example of change too rapid for many species. There are many examples of rapid and widespread extinction throughout geologic history.

Life can change the world and has usually done so slowly. Are we the first lifeforms who are able to change it so quickly that we can actually destabilize the system? Imagine if we could understand the mathematics behind the balance of nature. How can a system so complex keep itself relatively stable for millions of years? Can we ever understand such a system?