Deep Simplicity by John Gribbin, paperback
Gribbin provides an introduction to chaos theory and power law distributions in the world around us.
Was it really, I asked, that all this business of chaos and complexity is based on two simple ideas -- the sensitivity of a system to its starting conditions, and feedback? Yes, he replied, that's all there is to it.
Murray found that not only the spots of the leopard but also the stripes on a zebra, the blotches on a giraffe, and even the absence of patterning on the coat of a mouse or an elephant, can all be explained by the same simple process, involving diffusion of actuator and inhibitor chemicals across the surface of the developing embryo at a key stage during its growth.
The sand will pile up in a heap, until the slope of the heap reaches some critical value. Then, adding more sand will cause a landslide, or a series of landslides, making the sandpile slump down. Adding more sand makes the process repeat, until sand covers the entire table and dribbles over the edge when landslides occur. In this state, on average the amount of sand in the pile stays the same, with the same amount falling off the edge of teh table as is being added from above. the system is in a state of self-organized criticality, feeding off a flow of energy carried by the new sand grains being dropped on to the pile. And, just as in the way real earthquakes of any size can be triggered by stimuli of the same size, adding a single grain of sand may cause one large avalanche, or a series of small avalanches, or just leave the new grain of sand delicately balanced on the pile. But the pile always remains close to criticality.
Living systems characteristically bring local order to systems, making entropy 'run backwards' as long as they have an external source of energy to feed on...
The best way to look for entropy reduction processes at work on Mars would be to measure the chemical composition of its atmosphere. If there were no life on Mars, the gases in the atmosphere would be in a state of thermodynamic and chemical equilibrium, dominated by stable compounds such as carbon dioxide. If there were life on Mars, then the waste products from life processes would be dumped in the Martian atmosphere, providing reactive gases such as methane and oxygen, which would lower the entropy of the atmosphere.