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.
