Creationists, Mechanical Engineers, and the Second Law of Thermodynamics

April 2001
by Steven Novella, MD

Creationists are my favorite pseudoscientists. They toil endlessly to explore new ways to distort logic and misrepresent both the process and the findings of science. In so doing they provide a textbook example of why starting with a desired conclusion, then working backwards to fit evidence and logic into that conclusion, is a hopeless perversion of science destined to lead only to nonsense. If creationists weren’t somewhat successful in suppressing the teaching of science, specifically evolution, they would be merely amusing, however we are forced to take them seriously and continually remind the public and lawmakers that creationism (which includes intelligent design) is NOT science.

I was recently reminded, again, about the depths of illogic to which creationists will sink when I read two letters by creationists explaining how evolution must be wrong because it violates the second law of thermodynamics. The first was a personal letter sent to me; the second was an opinion piece published in the Hartford Courant and dutifully forwarded to me by a NESS member. Both authors, perhaps not by coincidence, assured the reader that they knew what they were talking about because they are mechanical engineers.

Mechanical Engineers

CT chapter chairman Jon Blumenfeld had noted to me earlier that a disproportionate number of members of the Institute for Creation Research (ICR) hold their advanced degrees in engineering. My anecdotal experience with these two recent letter writers seems to support the notion that there is some connection between engineers and creationism. It started me thinking about what this connection might be.

I do not mean to demean in any way the intelligence or training of engineers. Rather, I think there is a broader lesson to derive from this casual observation. Both letter writers believed that they were in a good position to judge the scientific merits of evolutionary theory because of their training in engineering. Engineers, after all, are real scientists who deal with concrete and complex machines, they argued.

Applying their mechanical knowledge to life has lead them to the confident conclusion that life must have a creator and that evolutionary theory cannot account for life’s complexity. They have fallen into the trap, however, of assuming that expertise in one area conveys automatic expertise in another area, or expertise over science in general. They have combined this hubris with the unjustified assumption that the methods of science employed by engineers are the only scientific methods that there are. So confident they are in their ability to judge biology by the rules of engineering that they feel they can dismiss an entire scientific discipline without ever studying it, or apparently even understanding it.

Engineer Ronald J. Parise displays the maximally annoying twin vices of arrogance and idiocy when he writes in the Hartford Courant:

“Anthropologists are ‘research scientists’ who normally come from nontechnical background such as history or less stringent technical curriculums in the natural sciences (biology or chemistry). Therefore, the ‘scientists’ who provide proof of evolution do not have the mathematical background or understanding to apply the Second law to biological systems.” (Parise, 2000)

But biology is not just engineering, and evolutionary theory is a subtle and complex discipline requiring specialized knowledge. Let us explore the second law of thermodynamics argument to see where these engineers went horribly wrong.

The Second Law of Thermodynamics

It is difficult to prove a negative, that something did not happen. Creationists cannot provide evidence for creationism (most likely because there was no creation for them to find evidence of) and so they are content to attack evolution. It is their hope that if enough doubt is thrown upon evolution, creationism will win by default (the false dichotomy logical fallacy). This strategy has prompted many critics of creationism to refer to such beliefs as “evolution denial.”

If, however, evolution deniers can prove that evolution is impossible because it violates a law of physics, then it doesn’t matter how much evidence for evolution biologists amass—if it’s impossible then it didn’t happen. This strategy is so seductive to creationists that they simply cannot resist it, and are therefore inspired to new depths of illogic.

The classic target of this tempting strategy is the second law of thermodynamics. As the name implies the law concerns the flow of heat energy from one body or system to another. The second law is expressed by the following equation:

(delta)S = q/T

Where (delta)S is the change in a property known as entropy, q is the amount of heat absorbed by a system, and T is the absolute temperature (Steiger, 1997). This sounds complicated, but all that it means is that when heat flows from a warmer body to a colder body entropy must increase. Since heat flows spontaneously from warm to cold, and not the other way around, entropy will spontaneously increase in any closed system, and will never spontaneously decrease. Entropy, however, may be decreased if the system is open, meaning that energy can be put into the system. A refrigerator, for example, can use electrical energy to cause heat to flow from its cold interior to the warmer exterior, thereby decreasing its entropy.

Entropy has another important relationship, and that is to probability. When a system goes from a less probable state (for example one with a high degree of order) to a more probable state (a more random and chaotic state) entropy is also increased. Since in any closed system total entropy can only increase, any increase in order in the system must be more than offset by a transfer of energy causing a larger increase in entropy than the decrease in entropy caused by the increased order.

By now you are likely wondering what all this has to do with evolution. Well, creationists like to oversimplify the second law of thermodynamics by stating that all systems must become more disordered over time. They draw analogies to everyday experience. If we do not expend energy to clean our house, for example, it will become progressively more disordered. Machines tend to break down over time, unless they are maintained and repaired. Living organisms also break down over time through the process of aging, and all living things eventually die, surrendering finally to entropy as decomposition returns their molecules to near maximal disorder.

Evolution is a process of increased order over time. When the earth first cooled and the oceans were formed, they contained nothing more than simple organic molecules. According to current theories of life origin, out of this “organic soup” more complex molecules formed, until eventually a molecule arose that was able to make a crude copy of itself. These molecules eventually evolved into single celled creatures, which over about three billion years evolved into larger, vastly more complex cells. One line of such cells developed the ability to divide into a collective group of cells, and multicellular life was born. Out of the first relatively simple multicellular organisms evolved all of the diversity and complexity of life on earth today.

Clearly, creationists have argued, such a continuous process of increasing order and complexity runs directly counter to the second law of thermodynamics. Evolution, they conclude, is impossible because it violates this well-established law. This argument is rhetorically very effective, because the analogies they draw are quite easy to understand. Everyone has experienced the tendency for disorder in everyday life, and no one can doubt that evolution is a process of increasing order (at least as an epiphenomenon if not a central feature). The argument, however, is based upon a critical misreading of the second law of thermodynamics. Creationists who use this argument are either unaware of this problem, or simply choose to ignore it because it does not suit their purposes.

The critical component of the second law which creationists have overlooked is that part about “closed systems.” A system is considered closed, for purposes of thermodynamic arguments, if it neither takes in or gives off any energy. Therefore, the total amount of energy in the system is fixed, and cannot increase or decrease. Energy can change forms – a log can be burned, for example, the energy in the chemical bonds between its molecules being converted into light and heat energy, without a change in the total energy of the system.

If you consider the example given above of one’s house, if the house were indeed a closed system, and no energy was imported into the system, it makes sense that eventually the house would fall into disrepair. If, however, the owners expend energy to clean and repair it, the house can maintain its order, and can even increase its order through additions and upgrades.

The question then becomes, is the earth, or more precisely the biosphere of the earth, a closed system? The answer is a clear and emphatic “No!” The biosphere of the earth receives a steady input of copious amounts of energy from two sources. The primary source is the sun. Heat and light energy from the sun continuously rain down upon the earth. Plants utilize light to create food through the process of photosynthesis. Animals then eat the plants for their energy. These animals (herbivores) are then in turn eaten by other animals (carnivores). When animals die, microorganisms consume their flesh, resulting in decomposition. The decomposition helps replenish the soil with nutrients which will be used by plants to make more food from sunlight.

The second source of energy, by-the-way, is geothermal. Heat from deep within the earth (supplemented by the heat of the decay of radioactive elements) radiates to the surface, heating natural hot springs, and causing volcanoes, which expel gasses which help replenish the atmosphere. Microorganisms have been discovered which live near natural heat vents on ocean floors. Some earth life, therefore, does not depend upon the sunlight cycle of energy.

The biosphere, therefore, is a very open system, with a continuous input of solar energy driving the system. Life uses this energy to carry out all of the processes of living – to grow, reproduce, and evolve.

Entropy, therefore, can be temporarily decreased through the input of energy. In fact, it can almost be predicted from thermodynamics that if a system, such as the earth, is experiencing a continual input of large amounts of usable energy, it should be in a state of decreasing entropy.

Some creationists have countered that the second law does not just apply to closed systems but to all systems; they are right, but they have missed the point. The second law does indeed apply to all systems, even open systems, but then the energy state of the system must be taken into account. As the equations above indicate, the order of a system may increase as long as there is a decrease in entropy, and entropy can decrease as long as the total amount of usable energy in the system increases. Refrigerators can freeze water into ice even in a warm room as long as it is plugged in, and plants can use sunlight to grow and reproduce as long as there is sunlight.

Some creationists, not willing to abandon their second law argument simply because it is wrong, have adopted several strategies to save it. For example, some creationists have argued that adding heat to a system does not allow for increased order (decreasing entropy), for heating a system only increases disorder. Ronals Parise writes: “Yet the only known observable effect of heat on a natural system is more chaos.” This, however, is a patently absurd argument. A sapling may grow into a large oak tree by using sunlight as an energy source. The oak tree is decreasing its entropy by using sunlight. Using solar energy to grow a tree is not the same as cooking a hamburger with heat. They have managed to miss the obvious fact that life can use energy to do work.

Other creationists have tried to argue that a system needs to already have the ability to use energy to decrease entropy. Organisms can use energy to grow and reproduce, but that is only because they have the genetic instructions to do so, and therefore they could not have used the process of evolution to get the information in the first place. What they are really arguing against, however, is not evolution (a process carried out by living organisms), but abiogenesis (the formation of life from non-life), making the argument a non sequitur. This is a common fallacy among creationists.

Evolution can occur only within a system that is able to use energy to self-replicate, which life can do. Therefore, even by the strained second law argument given above, life can evolve. How the system of life arose in the first place is a completely separate phenomenon from its subsequent evolution. Since abiogenesis is not a process which requires increasing order over time, the second law argument does not apply to it.

Another twist to this argument is that systems can use energy to decrease their entropy only by the action of an “outside agent.” Using the messy house analogy, they argue that an outside agent, a person, needs to expend energy to fix up the house, to decrease its entropy. The illogic here is the invocation of an “outside agent.” This is obviously meant to be an analogy for God. A person cleaning up a house, however, is not “outside” as far as thermodynamics is concerned. The person is actually part of the house system, because he is bringing energy into the house and is using that energy to perform work on the house. Thermodynamically we must consider the person and the house together, in which case we see that the person is expending energy and increasing his own entropy, in order to decrease the entropy of the house. The person is acting as a conduit for bringing energy into the system.

When applying this analogy to life we must consider that life is a self-organizing and self-renewing system. Life does not need any agent to use energy for growth and renewal. It is therefore also a self-organizing system. In other words, life is a system which is capable of using energy to do work and decrease its own entropy – all by itself and without any outside agents – as long as it has a supply of energy, which it does.

The final strategy employed by some creationists to rescue their second law argument is to apply it to the universe as a whole, rather than just life on earth. They acknowledge that the earth is not a closed system. The universe, however, is a closed system. If one considers the universe as a whole, it is clear that no energy either enters or leaves the universe. Again, it is free to change its form, but it cannot be created or destroyed. Therefore, they argue, it is not possible for the universe to have begun as a cloud of hydrogen gas and eventually evolved into all of the complexity it now contains without violating the second law of thermodynamics. Creationist Duane Gish has frequently quipped during his debates with scientists that “Evolutionists would have us believe that hydrogen is a colorless odorless gas that given enough time becomes people.”(Gish, 1994)

Once again, the creationists have employed deliberate illogic to misapply the second law. In fact, the total amount of entropy in the universe is increasing over time, as it must. There is no law, however, that states that entropy must be uniformly distributed throughout the universe, or that local temporary reversals of entropy cannot occur. It is possible, therefore, for a small corner of the universe to dramatically decrease its entropy, as long as this decrease is balanced by a greater increase in entropy somewhere else in the universe.

The process of fusing hydrogen into helium is the primary process which fuels our sun, and all the stars in the universe. As our sun burns hydrogen into helium it is greatly increasing its entropy as it spews large amounts of its potential energy out into space. The earth, orbiting close to the sun, picks up a small amount of this radiated energy, which it has used over the past four billion years to evolve life. The relatively small decrease in entropy represented by the earth is more than offset by the vast increase in entropy by the sun. The earth-sun system, therefore, has increasing entropy over time, as does the entire universe.

In other words, although it may at first seem counterintuitive, our universe had less entropy when it was comprised mostly of hydrogen gas, with some helium, as a nearly uniform cloud than it does today, even though the matter of the universe is now organized into heavier elements, stars, galaxies, and people. This is because some of the hydrogen was burned and some of its energy used and dissipated. The total amount of fuel in the universe, therefore, has decreased, which translates into a greater increase in entropy than the evolution of galaxies and life represents a decrease in entropy.

Evolution, therefore, does not violate the second law of thermodynamics. The second law allows for a system, such as life on earth, to decrease its entropy, as long as it has a supply of energy. Also, the total entropy of a closed system such as the universe can increase, in accordance to the second law, even while small pieces of the system experience decreased entropy.


This standard interpretation of the second law of thermodynamics is generally accepted by the scientific community as logically sound, internally consistent, and empirically validated. Why, then, do so-called creation scientists not understand and accept this argument? How is it possible that Duane Gish, who has a PhD in biochemistry, can base a belief on a fundamental misunderstanding of a basic law of chemistry? How can some mechanical engineers, despite training in mathematical and procedural rigor, fail to understand a simple equation, or realize the simple fact that trees use sunlight to grow?

The answer to these mostly rhetorical questions is that creationism is not a process of science or discovery. Creation science begins with a desired conclusion, that life on earth arose as a consequence of special creation and did not evolve naturally, and then works backwards to fit evidence and logic as best as possible into this desired conclusion. The misapplication of the second law of thermodynamics is an excellent example of the logical fallacies creationists are willing to commit in order to maintain their belief, and a cautionary tale of the hubris of attempting to dismiss with a single stroke a large body of scientific evidence you do not appreciate or understand.


1) Parise R. Science Does Support Creationism, Hartford Courant, January 2, 2001.
2) Steiger F. The Second Law of Thermodynamic, Evolution, and Probability. The Talk.Origins Archive, 1997.
3) Duane Gish’s Response to Richard Trott [Last Update: March 29, 1994]