In the past, various people have argued that life originating at all let alone evolving higher complexity over time was thermodynamically unfavorable due to the decrease in entropy involved with both circumstances, and thus it was believed to violate the second law of thermodynamics. For those unfamiliar with the second law, it basically asserts that the amount of entropy (often referred to as disorder) in a closed system tends to increase over time, or to put it another way, the amount of energy available to do useful work in a closed system tends to decrease over time. So it has been argued that since the origin of life and the evolution of life with greater complexity would entail decreases in entropy, these events are therefore either at best unfavorable (and therefore the result of highly improbable chance), or worse yet they are altogether impossible.
We’ve known for quite some time now that these thermodynamic arguments aren’t at all valid because earth isn’t a thermodynamically closed or isolated system due to the constant supply of energy we receive from the sun. Because we get a constant supply of energy from the sun, and because the entropy increase from the sun far outweighs the decrease in entropy produced from all biological systems on earth, the net entropy of the entire system increases and thus fits right in line with the second law as we would expect.
However, even though the emergence and evolution of life on earth do not violate the second law and are thus physically possible, that still doesn’t show that they are probable processes. What we need to know is how favorable the reactions are that are required for initiating and then sustaining these processes. Several very important advancements have been made in abiogenesis over the last ten to fifteen years, with the collaboration of geologists and biochemists, and it appears that they are in fact not only possible but actually probable processes for a few reasons.
One reason is that the chemical reactions that living systems undergo produce a net entropy as well, despite the drop of entropy associated with every cell and/or it’s arrangement with respect to other cells. This is because all living systems give off heat with every favorable chemical reaction that is constantly driving the metabolism and perpetuation of those living systems. This gain in entropy caused by heat loss more than compensates for the loss in entropy that results with the production and maintenance of all the biological components, whether lipids, sugars, nucleic acids or amino acids and more complex proteins. Beyond this, as more complexity arises during the evolution of the cells and living systems, the entropy that those systems produce tends to increase even more and so living systems with a higher level of complexity appear to produce a greater net entropy (on average) than less complex living systems. Furthermore, once photosynthetic organisms evolved in particular, any entropy (heat) that they give off in the form of radiation ends up being of lower energy (infrared) than the photons given off by the sun to power those reactions in the first place. Thus, we can see that living systems effectively dissipate the incoming energy from the sun, and energy dissipation is energetically favorable.
Living systems seem to serve as a controllable channel of energy flow for that energy dissipation, just like lightning, the eye of a hurricane, or a tornado, where high energy states in the form of charge gradients or pressure or temperature gradients end up falling to a lower energy state by dissipating that energy through specific focused channels that spontaneously form (e.g. individual concentrated lightning bolts, the eye of a hurricane, vortices, etc.). These channels for energy flow are favorable and form because they allow the energy to be dissipated faster since the channels are initiated by some direction of energy flow that is able to self-amplify into a path of decreasing resistance for that energy dissipation. Life and the metabolic processes involved with it, seem to direct energy flow in ways that are very similar to these other naturally arising processes in non-living physical systems. Interestingly enough, a relevant hypothesis has been proposed for why consciousness and eventually self-awareness would have evolved (beyond the traditional reasons proposed by natural selection). If an organism can evolve the ability to predict where energy is going to flow, where an energy dissipation channel will form (or form more effective ones themselves), conscious organisms can then behave in ways that much more effectively dissipate energy even faster (and also by catalyzing more entropy production), thus showing why certain forms of biological complexity such as consciousness, memory, etc., would have also been favored from a thermodynamic perspective.
Thus, the origin of life as well as the evolution of biological complexity appears to be increasingly favored by the second law, thus showing a possible fundamental physical driving force behind the origin and evolution of life. Basically, the origin and evolution of life appear to be effectively entropy engines and catalytic energy dissipation channels, and these engines and channels produce entropy at a greater rate than the planet otherwise would in the absence of that life, thus showing at least one possible driving force behind life, namely, the second law of thermodynamics. So ironically, not only does the origin and evolution of life not violate the second law of thermodynamics, but it actually seems to be an inevitable (or at least favorable) result because of the second law. Some of these concepts are still being developed in various theories and require further testing to better validate them but they are in fact supported by well-established physics and by consistent and sound mathematical models.
Perhaps the most poetic concept I’ve recognized with these findings is that life is effectively speeding up the heat death of the universe. That is, the second law of thermodynamics suggests that the universe will eventually lose all of its useful energy when all the stars burn out and all matter eventually spreads out and decays into lower and lower energy photons, and thus the universe is destined to undergo a heat death. Life, because it is producing entropy faster than the universe otherwise would in the absence of that life, is actually speeding up this inevitable death of the universe, which is quite fascinating when you think about it. At the very least, it should give a new perspective to those that ask the question “what is the meaning or purpose of life?” Even if we don’t think it is proper to think of life as having any kind of objective purpose in the universe, what life is in fact doing is accelerating the death of not only itself, but of the universe as a whole. Personally, this further reinforces the idea that we should all ascribe our own meaning and purpose to our lives, because we should be enjoying the finite amount of time that we have, not only as individuals, but as a part of the entire collective life that exists in our universe.
To read about the newest and most promising discoveries that may explain how life got started in the first place, read part two here.