Does Evolution Violate the Laws of Thermodynamics?
by Lenny Flank
(c) 1997
One of the most commonly heard arguments made by creationists centers around the laws of thermodynamics. The argument that "the Second Law of Thermodynamics makes evolution impossible" is probably the single most difficult one for evolutionary scientists to answer-not because the argument has any scientific validity, but because it revolves around concepts that are completely alien to persons without scientific knowledge and difficult for them to understand. Most "people on the street" haven't the slightest idea what "thermodynamics" or "entropy" mean, which allows the creationists to spew out an enormous amount of scientific-sounding but totally-wrong baloney.
Basically, the creationist argument goes like this: The Second Law of Thermodynamics deals with something called "entropy", which is a measure of the amount of disorder in a system. In most systems, entropy tends to increase over time. This is based on the fact that there is a limited amount of free energy in any closed system, and once that energy is used to do work (and thus produce order) it becomes unavailable for any further work (and therefore the order it produces tends to break down over time). I can use energy to do work and build a house, for instance. But once that energy is expended, the house will begin to decay and fall into disrepair-unless I keep expending more free energy to keep fixing it. In the absence of additional free energy, the house will eventually collapse. And unless I add energy to the system by performing more work, the collapsed pieces will never re-assemble themselves. The system always tends towards disorder, not towards increased order. And this increase in disorder or entropy is the essence of the Second Law.
The creationists assume that this tendency towards disorder and disorganization is a universal principle of all systems:
"All processes manifest a tendency toward decay and disintegration, with a net increase in what is called the entropy, or state of randomness or disorder, of the system. This is called the Second Law of Thermodynamics." (Morris, 1972, p. 14)
"There is a universal tendency for all systems to go from order to disorder, as stated in the Second Law." (Morris, 1972, p. 19)
"The Second Law (Law of Energy Decay) states that every system left to its own devices always tends to move from order to disorder, its energy tending to be transformed into lower levels of availability, finally reaching the state of complete randomness and unavailability for further work." (Morris, Scientific Creationism, 1974, p. 25)
Evolution, however, the creationists assert, constantly creates order as it moves from small less complex organisms to larger more complex ones. And this process of increasing order, they assert, is in violation of the Second Law of Thermodynamics, which, they claim, specifies that no system can move from a state of simplicity to more complexity. Therefore, evolutionary progression of life, they conclude, could not have happened.
The creationist argument is based on a fundamental misunderstanding of thermodynamics and the Second Law. The laws of thermodynamics only apply within a thermodynamically "closed" system, in which no free energy can enter from outside the system. Under such circumstances, the available free energy is used up and degraded until it can no longer do work, leading to thermodynamic decay and increase in entropy and disorder, just as the house in our example falls inevitably into disrepair.
However, as I pointed out, there is a way to reverse this trend towards disorder and maintain order-if I expend new energy and do more work. A system in which free energy is available from the outside is a thermodynamically "open" system, and in such a system it is possible to reverse entropy (by adding new free energy). This new energy comes at a cost, however-it reduces the amount of free energy that is available elsewhere and thus increases the entropy of the entire system.
The universe itself, for instance, is a thermodynamically closed system. No new free energy can enter it from the outside, so its entropy inevitably increases. In fact, entropy will inevitably destroy it, sapping and using up all of its free energy and reducing it to a cold inert realm where there is no energy flow, a condition known as "heat death".
Contrary to the creationist assertions, however, the Second Law and increasing entropy do not apply in "all systems"--only in those with no influx of free energy. The Second Law applies only within a closed system. Life on earth is not a thermodynamically closed system-it is constantly receiving free energy from the outside in the form of sunlight and solar energy. Life on earth is capable of channeling this free energy to do work and thus to decrease entropy and actually move from disorder to a higher state of organization.
However, while the earth is using this free energy from the sun to decrease its entropy, the solar system as a whole is experiencing increased entropy, and will inevitably die out as the sun uses up all its free energy and reaches heat death. Until that point, however, free energy is available on earth to do work and reduce entropy locally, and this allows life to become more and more organized (less entropy) even though the solar system as a whole is losing free energy (more entropy).
An analogy may be useful here: all streams and rivers run downhill, but near rocks and other obstructions small portions of the stream can use kinetic energy to temporarily and locally reverse this flow and actually swirl uphill for a time. The water molecules use free energy from the outside to do work and thus temporarily circumvent the flow of gravity. The fact that parts of a vortex flow uphill does not invalidate the affects of gravity on water, any more than the fact that life locally decreases its entropy invalidates the Second Law. Both processes are temporary and completely dependent on an outside source of energy.
Thus, the evolution of life does not violate the Second Law--it merely uses available free energy to circumvent it temporarily, just as some parts of a water vortex move upstream without violating the laws of gravity. The Second Law says that free energy tends to be reduced through time. This does not at all mean that free energy cannot be temporarily used to do work and thus reduce entropy in a localized area--but even then, the total free energy of the system continues to decline. Even as life on earth reduces entropy by utilizing free energy, the sun that provides that free energy burns out and increases its entropy. In the end entropy will win, and the solar system (indeed, the whole universe) will die a heat death at maximum entropy. Life on earth is a temporary blip in the process of universal downwinding. In the meantime, however, local processes can reverse this flow and temporarily produce small local areas of organization and lower entropy-areas which we call "life".
Life is not the only process where we can observe a decrease in entropy and the spontaneous appearence of order from disorder. Snowflakes, for instance, are formed when randomly moving water molecules use energy to arrange themselves in an orderly crystalline pattern. Shallow pools of water, in which water molecules move randomly, can use sunlight energy beating down upon them to form regularly constructed and orderly convection cells.
The creationists, realizing that order can after all come from disorder without violating the laws of thermodynamics, thus are forced to change their argument-they now assert that such change can only come about through some sort of "mechanism", which, in the case of life, they assert, can only be Divine in origin:
"Disorder can never produce order through any kind of random process. There must be present some form of code or program, to direct the ordering process, and this code must contain at least as much 'information' as is needed to provide this direction. Furthermore, there must be present some kind of mechanism for converting the environmental energy into the energy required to produce the higher organization of the system involved. ... Thus, any system that experiences even a temporary growth in order and complexity must not only be "open" to the sun's energy but must also contain a "program" to direct the growth and a "mechanism" to energize the growth. " (Morris, 1972, p. 19)
The creationist assertion that there is no natural "mechanism" to produce ordered life from disordered chemicals (other than Divine Intervention) is simply not true. The unique chemistry of carbon atoms makes it possible for these atoms to use free energy (in the form of photons from the sun) to break and re-form chemical bonds and thus form long chains of atoms---the root chemical basis for life. Nothing mysterious about this and no Divine Miracle required--simply a consequence of the laws of chemistry and physics as they apply to the outer electron shell of a carbon atom. The laws of chemistry and phsyics that govern the formation of biological molecules are the very same ones that govern the formation of any other carbon compound. At the chemical level, there is nothing different about "life"--the chemistry of a carbon atom is the same whether that atom is part of a DNA molecule or whether it is part of a lump of coal.
Therefore one needs not only an influx of free energy (which comes from the sun), but also a mechanism to capture that energy and use it for biological processes. Fortunately for life on earth, the unique chemistry of carbon atoms makes this a rather straightforward process (it is so simple, in fact, that amino acids are found floating free in interstellar space, where they form spontaneously from carbon chains utilizing free energy). Similar chemical processes, powered by the same free energy from the sun, allow life to grow in complexity, without in any way violating any of the laws of thermodynamics.