The second law of thermodynamics sometimes seems the cornerstone of the creationist argument. After concluding his discussion on this proven scientific principle, Henry Morris claims that “evolution and the Second Law cannot both be true.”[3] What is the second law of thermodynamics? And how does an evolutionist answer it?
First, a complete explanation of the second law is beyond the scope of this essay, but I will briefly describe it to show the problem. Thermodynamics studies changes (-dynamics) of heat and energy (thermo-). All energy is not created equal. Some forms are more useful than others. For example, gasoline contains chemical energy that can be transformed into motion of a car.
Heat is the energy of random molecular motion, and can be considered the energy with the lowest quality. Heat cannot be readily used to do work. For this reason, other forms of energy are considered “useable” while heat energy is considered wasted. “Work” is what creates order from chaos or can make a car drive uphill. No process is 100 percent efficient. In every reaction, some heat is always produced. For example, a car’s engine heats up because it cannot convert 100 percent of the chemical energy in the gasoline into mechanical energy. Some of the gasoline’s energy is wasted as it dissipates as heat, which increases the random molecular motion of the surroundings. Eventually, all energy dissipates as heat. Even the moving car is eventually stopped and its energy flows out as the heat of friction between the brakes, tires and road.
The second law of thermodynamics states that all energy flow produces more disorder. This disorder, chaos or randomness is measured by a term called entropy. Thus, as entropy increases, disorder increases. Since no process is 100 percent efficient, every process will create some unusable heat. The second law says a process can occur on its own only if it increases the disorder or entropy of the universe.
This creates a potential problem for evolutionary biology. Evolution implies the development of complex life forms from simpler components. If the evolution of life involves a decrease in entropy (i.e. increase in complexity), then it should not occur spontaneously without help, as atheists maintain.
The evolutionist rightly answers by pointing to certain “exceptions” to the rule. You began life as a single, egg that divided many times to produce a complex person. You started simple, but as you grew, the complexity of your body increased on its own. So then at least some natural processes that create order can occur spontaneously, and this does not violate the second law. But how?
Remember that the second law states that every process must increase the entropy of the universe. That last phrase is important. It means that the entropy of a person’s body can decrease, as long as the entropy of the person’s environment increases more. It is analogous to a refrigerator, which can cool down inside, but only at the expense of heating up the rest of the room. Similarly we can increase in complexity as we grow, but only at the expense of heat and disorder of the rest of the world.
Some decreases of entropy can occur in an “open system,” which means the “system” is open to energy input from the outside or from the environment. For example, your refrigerator gets energy from the electrical socket. The useable energy from the outside can replace the energy that was lost as heat, so the organism or machine can still have enough energy to do work and create order. But outside the system, the entropy does increase. This explains how evolution does not violate the second law of the thermodynamics when it claims life evolved on Earth. The Earth is an open system because it has energy coming in from the Sun. So if life evolved on Earth and its order increases, the second law can still be satisfied as long as the order of the Sun decreases more. “The second law requires only that processes increase the entropy of the universe. Open systems can increase their order at the expense of the order of their surroundings.”[4]
Some creationists are frustrated with this “open system” argument, and have responded to it, but their responses are more philosophical than scientific and begin to blur this issue by introducing factors we cannot measure. The creationist Henry Morris maintains that simply having an open system is not enough to get a local increase of order. One must also have a mechanism of converting energy input into useful energy and a program to direct the process of ordering. For example, a baby’s genes provide a program by which the body forms from simpler substances.
However, the second law of thermodynamics does not mention either a “program” or a “mechanism” for energy conversion. While Morris is correct to say that a mechanism, or algorithm, could inject information into the system and thereby reduce entropy, it does not follow from this that such mechanisms are the only ways to decrease entropy locally. For instance, when you dissolve sugar in water, then put it on a windowsill with a string in it, you eventually get “rock candy”—basically a big sugar crystal that has more order than the sugar-water solution. However, this does not introduce much order into the system, and even if it did, it is a perfectly normal natural process that increases entropy in one place to get it in another. Furthermore, some evolutionists have claimed life started by crystals; while this is wrong, what it shows is that there are natural processes out there that possibly reduce entropy locally by nothing more than a commonplace natural process. So we can’t just prove evolution wrong by appealing to entropy.
In fact, the second law itself doesn’t make any statements about what conditions are required to achievelocal ordering at the expense of an increase in total entropy of the universe. It doesn’t say if an “open system” is the only requirement or if there are more. We just know that local ordering is possible by purely natural processes, and does not necessarily contradict the law. This leaves scientists to argue about exactly what must be required to get a local decrease in entropy.
Therefore, the second law of thermodynamics does not prove that evolution is impossible. So please don’t be like some creationists who quote the second law as a conclusive proof that evolution is false. There is no such proof because evolution is not a deductive argument. However, we might be able to argue that the second law shows evolution to be more unlikely. That’s how evolution will eventually come down. As we bring more and more evidence that shows evolution unlikely, the belief in evolution becomes less and less plausible. Eventually, with enough evidence it becomes so ridiculous that only a fool would believe it, even though it is technically still possible.
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