Entropy is a concept that describes a phenomenon in the natural world that applies to everything that is physically material.
One typical example used to define what is entropy is to describe the variations possible between the perfectly neat and organized bedroom of a teenager with everything in its place, contrasted with the near-infinity of possible disorganized arrangements of these same elements scattered all over the bedroom.
This example applied to the natural world is suitable as an explanation we can understand, but is inaccurate in that it involves the human agency of a teenager as the cause of this disorder.
But staying with this example, the condition of a perfectly neat, clean, and organized bedroom is called in physics a macro-state, having generally only one condition, iteration, or reality.
The enumerable conditions of possible disorder of the bedroom are called in physics micro-states.
Give the typical teenager autonomous control over the state of their bedroom and the usual result is for the organization of the bedroom to decay into harmless disorder, yet nevertheless annoying to the parents.
Physically material phenomena in the natural world that have the potential to disburse or expand into a large number of possible alternative combinations or conditions are said to have high entropy…the high capacity to change into other states.
Physically material phenomena in the natural world that are fixed in their current state and are not amenable to changing from a singular macro-state to enumerable, alternative micro-states, are said to have low entropy.
Physically material entities if left to themselves will morph from highly ordered and well-defined macro-states having low entropy toward randomly disordered micro-states displaying high entropy, sometimes observable and even measurable in action over time.
It is therefore said that our universe as a whole uniformly displays positive entropy, going from the low entropy of neat, ordered, and well-defined to the high entropy of scattered, diffused, and randomly disordered.
Returning to the bedroom example, it takes the agency of the teenager to apply work to maintain the macro-state of a clean and organized bedroom with everything in its place, or the absence of work on the part of the teenager allowing the bedroom to naturally fall into disorder.
This example of the macro and micro states of a teenager’s bedroom is easily understandable to us, but in a natural world left to operate on its own, human agency is not a factor influencing entropy.
An example close-to-home that does not involve human agency is the sun in our solar system that is constantly changing hydrogen into helium, producing heat but also reducing the size of the sun.
The sun can then be said to be engaged in the positive entropy of changing from the initial macro-state of decreasing quantities of less and less hydrogen atoms to the subsequent micro-state of increasing quantities of more and more helium atoms.
The beginning disparity between the larger number of hydrogen atoms compared to the lesser number of helium atoms is what enables atomic reactions to occur that produce the light and heat of stars throughout the cosmos.
This will eventually, over the span of a few more billion years, result in the “heat death” of an equilibrium parity between hydrogen and helium atoms inside our sun that can no longer generate atomic reactions…producing a state that is called maximum entropy having exhausted all of the possible micro-states available.
We do not currently understand what entropy is, and why it exists.
We can observe its occurrence in a variety of examples in the natural world, such as tires on our automobiles that wear-out and need to be replaced, cavities in our teeth that require a trip to the dentist, and roofing on our houses that will only be guaranteed to last for 40 years.
One key point in trying to understand entropy in the natural world is that it applies only to physically material things.
Entropy does not apply to information…being an abstract, non-material reality.
Information can be refined, revised, and improved, but it is not susceptible to entropy in the same way that physically material entities are generally bound to the positive direction of low entropy states to the high entropy of randomly disordered states, in the process of change over time throughout the universe.
This process of change over time demonstrated through entropy is not an argument for Darwinian evolution, but is instead a compelling argument for the existence of an intelligent designing agent.
There are certain values within the mathematical equations that describe the physics of phenomena in the natural world that fall outside of the universal actions of entropy.
The numerical constants within the equations that describe the speed of light, the strength of gravity, the expansion rate of the universe, the carbon resonance inside supernova stars that create carbon and oxygen, and the atomic weights of the fundamental particles in the Periodic Table, for example, cannot be changed or altered through entropy.
These numerical constants within the equations that describe the laws of physics appear to be fixed and inviolable throughout the vast expanse of the universe.
This is an excerpt from my book Pondering Our World: Christian Essays on Science and Faith.
The Cross in the Christian Life 