It is a brave person indeed who attempts to explain the nature of the universe before the Big Bang, especially without resorting to religious or New Age waffle. The old adage, “anyone who claims to completely understand Quantum physics is either a fool or liar,” could be extended to “attempts to explain the beginning of the universe.”

Kinney is neither! He has provided in this book a well-argued thesis that helps us to expand our understanding, and notably our exceptions to understanding, the genesis of the (not our) universe.

Considering the complexity of the subject matter, this book is extremely well written. The reader may ignore the smattering of mathematical equations without losing their way in the Kinneyian multiverses. He uses simple analogies to explain complex cosmological conundrums – introducing to the reader the well-established theory of “cosmological inflation”.

The book has eight chapters, with explanatory diagrams and drawings, followed by a Glossary, Further Reading, and Notes. The glossary is very useful for readers not well versed in physics. For example, it explains the difference between “dark matter” and “dark energy.”

Chapter – 1 The Beginning of the World

Chapter – 2 The Standard Cosmological Model

Chapter – 3 The Cosmic Horizon

Chapter – 4 The Physics of Nothing

Chapter – 5 The Quantum Vacuum and Cosmic Structure

Chapter – 6 Testing Inflation

Chapter – 7 Eternal Inflation and the Multiverse

Chapter – 8 Just So Stories

Chapter 7 had me enthralled. I could not read fast enough, back to this shortly. Leading up to Chapter 7 Kinney shows that, “...every observer sees themselves as stationary at the “center” of the expansion. In this way, no location in the universe is privileged, consistent with the cosmological principle” (pp. 16-17).

As mentioned, this book explains the theory of cosmic inflation. “This remarkably powerful synthesis of gravity and quantum mechanics enables inflation to provide a single, unified picture for the physics of the very early universe as well as the initial conditions for the hot big bang” (pp. 113-114). Later in Chapter 6 Kinney notes, “I hope I have convinced you in this chapter that inflation is a well-posed scientific theory in the classical sense of predictivity and falsifiability – in fact with great detail and precision” (p. 134).

Kinney is a scientist and is at pains to make sure his ideas and theories comply to the scientific basics of falsifiability, testability, and accurate observation. “Starting as a theoretically motivated argument explaining the large-scale properties of flatness and homogeneity in cosmology, inflation has been developed over the period of a few decades into a precise and predictive scientific theory” (p. 139).

Parts of Chapter 7 came as somewhat of a surprise in that Kinney discusses the “anthropic principle.” Basically, this is the monotheistic religions’ concept of the existence of a God. He, satisfactorily to my mind, demolishes this mythological fantasy using testable scientific criteria. Kant argued that we can “neither prove nor disprove the existence of God.” Kinney, I believe, shows with our incredible advances in cosmology and physics that this stance no longer holds true. It is worth quoting him in full regarding this, as it is of great importance to us on this planet in the here and now, and for our future:

“Ultimately, the anthropic principle depends in an integral way on the assumption that we are in some deep and fundamental way special, or what you might call “carbon exceptionalism.” Only a vanishingly rare set of circumstances will create beings such as us so that we must have a universe finely tailored to our existence. Not only is this an embarrassingly anthropocentric notion, it clashes with the foundational idea dating in its earliest form to Copernicus: the cosmological principle” (p. 168).

An Infinity of Worlds is on the one hand a small book, and a delightful, easy read - on the other hand it is metaphorically as large as the complex, infinite universes it discusses. As such it does not, in fact cannot, provide a single precise answer to the nature of the universe before the Big Bang. It does however provide a comprehensive “best fit” description of the universe, utilising the very latest, sound scientific knowledge we have. Which summed up in one sentence is: “So, yes, the universe – our universe – really did have a beginning” (p. 193).