Friday, 29 March 2013
Life is just a fancy way for water to get around.
Most narratives of the evolutionary story focus rather predominantly on the notion of competition, of natural selection, of survival of the fittest. Granted, the forces of natural selection are ever present in a resource limited environment (such as the Earth). Organisms must compete with each other for nutrients, shelter, and mates, and those most successful in competition will be most likely to reproduce. It is a well worn story, and it has been extraordinarily important in overthrowing an ancient obsession with anthropomorphized deities and creation myths. But this is the 21st century, and as we mature finally into the era of a technologically competent whole globe societal system, with an ever growing population and an ever more apparent scarcity of resources (and competence...), it becomes essential that we re-evaluate our understanding of the development and maintenance of sustainable systems (such as organisms and ecosystems), if we are to avoid out-competing each other into nuclear holocaust.
Organisms are, fundamentally, sustainable systems. That is their very essence. They operate under meager inputs of energy and achieve efficiencies unheard of in human engineering (leaving aside those engineers now turning to bio-mimicry - we'll get to that). They can withstand numerous large perturbations or disturbances (relative to their size), and in many cases come out not just alive and well but stronger than before (they are anti-fragile!). They are enduring and productive, and in the case of humans (or ecosystems), capable of immense creativity and profound transformations of the physical environment. Is all of this merely a matter of competition and descent by natural selection?
The simple answer is: most definitely not. I contend, along with a growing number of others (mathematicians, physicists, ecologists) that much of the natural beauty and profound capacity of living systems derive not from the arms-race of natural selection but from the inherent pattern-forming processes that underlie the dynamics of our universe. Life on Earth is a Cosmic phenomenon, and don't you forget it!
See, living systems are first and foremost physical systems. They are built out of molecules and ions, and are as subject to the fundamental physical laws of the universe as anything else. If we are going to understand their profound capacities for efficiency, work, and ultimately creativity, we must take stock of some physics. Now, the laws of physics are unreasonably simple - I am not being facetious. There is no reason that physics should be as neat and tidy as it is, given the overwhelming complexity of the physical universe. But, fortunately for us (perhaps necessary for us), much of it is surprisingly easy to understand. Of course there is the further matter of carrying out detailed calculations, but that is essentially irrelevant (if you are merely interested in ideas), and is ultimately designated to a computer.
To understand the physics of living systems, we begin with a simple system, a hot cup of coffee on a table in a room-temperature environment. What is happening to our system, the cup of coffee, and to its environment, the room? Clearly, the temperature of the coffee is running down - heat is leaving the cup (we can usually see it, and it is usually very pretty) and entering the room. Why is it doing that? Well, the coffee is made up of (liquid) particles bouncing around in a cup, and the environment is made up of (gas) particles bouncing around in a room. The coffee is hotter, so its particles are moving faster, and so it is overwhelmingly likely for some of them to bounce their way out of the cup, and into the room, but it is not nearly as likely for particles in the room to bounce into the cup. So heat (the bouncing of particles) leaves the cup. When the temperature of the cup reaches that of the room, the chance of a particle leaving the cup and one entering the cup are the same (since they are all going at the same speed, on average), and so we say the system has reached equilibrium.
If given the opportunity, all systems will eventually reach equilibrium. This is entirely a matter of statistics. At equilibrium, things are relatively boring. But on their way to equilibrium, things are much more interesting. Indeed, the coffee-cup heat is only a simple example. Far more fascinating are the patterns in rivers, galaxies, neurons, and trees. Ultimately, all of these designs
stem from a common origin in the statistics of non-equilibrium systems. Ultimately, I contend, this is the essential character of life on Earth, which is only supplemented and encouraged by the forces of competition and natural selection.
So let's make more concrete steps from coffee mug to living system. First of all, consider a situation in which we maintain the heat of the coffee, say by keeping it on a hot plate, and the amount of coffee, say by having a constant (very small) influx into the cup to offset evaporation. Then the system will dissipate heat indefinitely (and display beauty indefinitely in the heat patterns!), as it will never be able to reach equilibrium, since we continue to drive it by providing more coffee and more heat. Such a system we call a driven, dissipative, non-equilibrium system, or just a dissipative system for short. Its driven because there is constant energy input (coffee and heat), its non-equilibrium because there are gradients present (temperature difference between coffee and room), and its dissipative because heat is constantly leaving the system.
Living systems, similarly, are driven, dissipative non-equilibrium systems. They are driven by sunlight (ultimately) and nutrients (more generally), they are non-equilibrium because they are chalk full of gradients and structure and interesting patterns (which don't occur at equilibrium), and they are dissipative because they give off heat (the reason night vision goggles work) and excrete waste. So they are very much like our coffee cup. If we did in fact let the coffee cool down, to equilibrium, we might then say that our system has 'died', since it no longer displays interesting patterns. Similarly, for an organism, if we deprive it of food (nutrients and/or sunlight), it will die, eventually reaching equilibrium, where there are no more interesting patterns (like lungs and brains and fingers and bellybuttons and eyeballs).
Now, this tendency for systems to decay to equilibrium, to dissipate gradients, and to degrade the quality of energy available to them, is known as the Second Law of Thermodynamics and is one of the hottest topics in physics, even to this day, despite it being over a hundred and fifty years old. Essentially, the 2nd Law defines the sorts of processes we can expect to occur in the universe: a cup falls of a table and shatters into a hundred pieces, but doesn't spontaneously re-assemble into a cup; hot things cool down, but cool things don't heat up (unless you heat them); a drop of ink in a glass of water diffuses out until the concentration is equal everywhere, but doesn't spontaneously re-condense into a drop; and so on. How is it then, in the context of a universe where gradients are always set to run down, that systems as complex as cells and organisms and ecosystems could possibly be built up? Indeed, this is the standard argument of creationsists and religious folks who know only too little physics.
The key is driving and dissipation, as we noted above for the coffee cup. A system which is driven and dissipative spontaneously organizes into wonderful patterns as it attempts, as best it can, to dissipate the driving energy. The patterns that form in cigarette smoke are precisely these sorts of patterns - they emerge in the pursuit of dissipating the energy available in the form of burning tobacco. The patterns that form in the Earth's atmosphere are similar - they emerge to facilitate the dissipation of the sun's energy into heat. Hurricanes and tornadoes, which in and of themselves are highly structured patterns, emerge because they facilitate the destruction of many other surrounding patterns - ie. they facilitate the dissipation of gradients and the degradation of energy, in direct accord with the Second Law. Self-organization in one place, then, emerges in order to facilitate disorganization in another.
On Earth, the primary system for dissipating the incoming sunlight energy is the water cycle. The patterns of the atmosphere, which are many and quite formidable, exist because they facilitate the dissipation and degradation of the sun's energy. If they weren't there, then sunlight would just bounce back into space with the same energy it had coming in. But this is less likely, according to the Second Law, and so we have the formation of patterns in the atmosphere.
Living systems emerge as an extension of the water cycle, in its capacity to dissipate and degrade sunlight. Life augments the ability of the water cycle to dissipate the sun's energy. As a result, less sunlight is reflected back into space, and more heat is produced. According to the Second Law, this is a favourable result. So from the perspective of this analysis, Life is actually highly probable on a planet such as ours (with abundant water and carbon), as it complies directly with the Second Law of thermodynamics. So, contrary to the argument of the creationist (which asserts that Living Systems, by containing so much structure, violate the second law), Life is actually a result of the Second law, since it facilitates the dissipation and degradation of the sun's energy on Earth. Hence life is more favourable, thermodynamically, then no life.
So how do you like that?! Life is just an extension of the water cycle. Or, if you like, life is just a fancy way for water to get around!
At this point I think it is constructive to take note of the difference between Human engineering and Natural engineering. Human's are concerned predominantly with the conversion of heat into work. We burn liquid fuels, giving off immense amounts of heat (and patterns in the heat, but we mostly ignore these), and use that heat to drive turbines to produce electricity. We know, however, and have known for as long as we've had the second law, that this process is fundamentally inefficient, in that one cannot convert all of the heat released into an equal amount of work (this is known as Carnot's theorem). On the other hand, Natural engineering (if we may use such a phrase) is concerned with the exact opposite process, that of converting work into heat: sunlight comes in (work) and is dissipated as heat. But in between, a whole myriad of processes occur which siphon off the energy of the sun and use it to drive the various cycles and reactions that constitute Life, before the energy is ultimately dissipated. Somewhat paradoxically, energy ends up being stored in the system for an extended period of time, contributing to its highly ordered and structured dynamics and profoundly beautiful patterns. In this way, living systems become thermodynamically favourable by adhering to the Second Law, and so are anti-fragile. In contrast, human engineered systems are profoundly fragile - small mishaps can lead to devastating consequences.
I suspect that in the near future, we will learn to engineer society to derive all its energy needs from incoming sunlight, and to comply more directly with the second law, slowly siphoning off the energy for the myriad processes of our socio-economic system, storing it on board for extended periods of time, and finally dissipating it as heat. In this way, we will become more thermodynamically favourable and ultimately anti-fragile. We will become sustainable.