The Second Law of Thermodynamics: An excerpt from the Dictionary of Christianity and Science

On April 25, 2017, Zondervan will publish the Dictionary of Christianity and Science. This is the definitive reference book discussing the intersection of Christian faith and contemporary science.  It has been a project that has taken over five years to complete. The four general editors, Paul Copan, Tremper Longman III, Christopher L. Reese, and myself have worked with over 100 outstanding contributors and our amazing editor, Madison Trammel, to bring this book to fruition.

There are a few features of this book that separate it from other such works. While most articles in the dictionary are unbiased, for topics that are controversial among Christians, the Dictionary presents various advocacy articles with opposing views. For instance, different views on evolution and the length of the days of creation are included. These articles represent the viewpoint of the author and are not completely unbiased. This multiple presentation model serves as a great resource for each reader to understand the complexities of the issue and come to his or her own conclusions.

Most of the articles in the Dictionary relate the particular subject to some aspect of Christian thought. For instance, articles on Special Relativity or Conservation of Energy have a concluding paragraph that mentions how some aspect of that subject relates to the character of God. This feature that explicitly discusses the intersection of science and faith distinguishes this reference book from others.

I have written 22 of the 450 or so articles. If you preorder the Dictionary you will get a number of bonus features including a presentation slide deck discussing String Theory which includes one of the articles I wrote on that subject. As an introduction to the Dictionary the rest of this post reproduces the entry I have written on the Second Law of Thermodynamics. This reprint is copyrighted by Zondervan and the four general editors and is used by permission. At the end of this article I briefly discuss the relationship of the second law of thermodynamics to biological evolution. I want to point out that I am not advocating for evolution but just stating facts regarding whether or not evolution violates the second law of thermodynamics.

A Changing Arrow of Time?

This is one post I am not looking forward to writing.  Some of my readers have asked me to comment about alternative theories to the Big Bang which remove the necessity of our universe having a beginning.  I have been thinking for some time about how to write on this subject in a non-technical manner, which is the tone I strive for on this blog.  Because most of these ideas are quite theoretical, requiring complex mathematics and intricate nuances, it is quite a challenge for me to give an accurate and adequate description of most of these proposals, yet still be comprehensible.   Nevertheless, in this post I want to try to discuss the paper by Anthony Aguirre and Steven Gratton (AG) that describes a scenario which they claim requires no beginning.¹   I also want to give some thoughts on how their idea fits into the whole discussion of evidence for or against a deity, particularly the Christian God.  My attempt may be an epic fail.

In the model proposed by Aguirre and Gratton, they claim to avoid a beginning by proposing a thermodynamic arrow of time that points in different directions depending on whether the universe is expanding or collapsing.  To understand what this means I need to first take a diversion to discuss what the thermodynamic arrow of time means.  Actually, no one really knows for sure why we experience time moving forward but we do know that a quantity called entropy must increase in any non-reversible process.  Entropy strictly has to do with the number of microstates available to a system. The concept of a microstate can be illustrated by considering two six-sided dice. There is only one microstate available for the dice to roll 2: both must show a one. However, there are six possible microstates available for the dice to roll a 7. The combinations are 1 and 6, 2 and 5, 3 and 4, 4 and 3, 5 and 2, or 6 and 1. Because there are more available microstates, the dice will more often roll a 7. A macroscopic system with more available microstates has a greater entropy than one with fewer microstates. The second law of thermodynamics states that an isolated system will evolve spontaneously to the state with maximum entropy.   This is a statistical idea.  In general, all processes move toward those that are more statistically probable.  That gives us the arrow of time.   Time moves in the direction where entropy increases.