Entropy always increases, and its opposite is an unlikely state like an egg, so why is order all around us? For example, day follows night, seasons cycle, plants produce food to eat, and air to breathe, in a synergistic, self-regulating system that some call Gaiea. Is life on earth then just a local anomaly that bucks the universal trend?
A fridge that keeps beer cold on a hot day is an anomaly, but it doesn’t deny the second law because it uses electrical energy, so is the earth the same? It has the sun to power it, but earth isn’t the only planet that orbits a star, they all do, so it may be lucky but it isn’t an anomaly. It also needs order above it, as the sun has to keep its planets in order for the earth to evolve life, and that requires the galaxy to keep its stars in order, so if life depends on a cosmic order, it isn’t an anomaly.
The other possibility that physics allows is that the big bang was highly ordered, so life can still occur because the universe is only half-way through its devolution:
“The ultimate source of order, of low entropy, must be the big bang itself. … The egg splatters rather than unsplatters because it is … the drive toward higher entropy … initiated by the extraordinarily low entropy state with which the universe began.” (Greene, 2004), p173-174.
In this reverse logic, our universe had to begin very ordered because the second law rules, but that the initial chaos was highly ordered makes no sense at all. How is the white-hot plasma that came before atoms and molecules formed, let alone stars, highly ordered? If there was a prize for backward thinking (Note 1), this would surely be a top contender.
How then did ordered life begin? Our earth is over four billion years old, but for most of that time hosted only single-cell organisms like bacteria. Then about two billion years ago, as continents formed and volcanoes erupted, these bacteria caused the great oxidation event that produced an atmosphere suitable for higher life. Even so, another billion years passed before somehow, somewhere, the seemingly impossible occurred. Two primal cells with quite different architectures, archaea and bacteria, merged into one complex cell, that led to plants, animals, and us (Lane, 2015). Then about half a billion years ago, modern life began, leading to human beings about three million years ago, which is like the blink of eye in the earth’s timeline. The chances of life arising on earth are more than a trillion to one, so to call it a devolution based on a heat engine law is ridiculous.
Bacteria are still here because they know how to survive. Bacteria in boxes placed outside the International Space Station for a year revived when back on earth because under harsh conditions, they can form spores that are dead metabolically but recover when conditions are right, even after many years, so they could hitch a ride on a meteor to travel between planets. The panspermia hypothesis, that life can evolve on one planet and spread to another, means that bacteria from mars could have colonized the earth.
Whether this happened or not we don’t know but bacteria exist on earth, so it is likely that many of the mind-boggling 160 billion planets in our galaxy host them too. If so, a galaxy full of life isn’t what the second law predicts after 14 billion years of decay! Life arose on earth by a highly improbable sequence of events that defied seemingly impossible odds, so what caused it?
Note 1. Backward thinking explains an already known answer by tweaking it to fit the facts, or the facts to fit it, so it produces no new knowledge. In contrast, forward thinking begins with a question and lets the evidence provide an answer, so it does produce new knowledge. Science is based on forward thinking not backward thinking (see Research Roadmap).