I thoroughly enjoyed the book * “Life on the Edge”*, by McFadden and Al-Khalili. I especially enjoyed renewing my amateur relationship with Quantum Physics. I therefore decided to choose another science book, and selected

*by world renown physicist Roger Penrose.*

**“Cycles of Time”**Penrose is a brilliant scientist, and has made very significant contributions to both physics and cosmology, having worked closely with modern pioneers such as Stephen Hawking.

I must confess, however, that I struggled terribly at times to comprehend and appreciate the science which Penrose was presenting. Whereas * “Life on the Edge”* was clearly written for the layman science enthusiast,

*took a much more scientifically rigorous approach. Penrose invested many pages and much effort to both explain and mathematically defend his hypotheses. Optimistically, I may have been able to both understand and appreciate this approach 30+ years ago, when both my physics and math skills were at their peak. Presently, I simply found myself overwhelmed and overburdened trying to struggle through difficult and rather dry mathematical analyses.*

**“Cycles of Time”**I found this rather unfortunate, because at its core, Penrose actually was exploring some very interesting concepts and presenting some leading edge insights into the current theories of both the origin of our universe and its likely demise.

Fundamental to the book, serving as almost the heartbeat of the scientific narrative, is the Second Law of Thermodynamics, which basically states that entropy always increases. Entropy is a measure of order of a system.

Penrose did a good job of introducing the concept of entropy, by using a bucket containing red and blue paint. Initially, the red and blue paint are separate and distinct, but stirring the paint will result on the mixing of the red and blue paint, the result being a mixture of pigments which will appear purple. Why can’t the paint be “unstirred?” It is the Second Law of Thermodynamics which requires that entropy flows naturally only from order (red and blue) to disorder (purple). Yes, the purple paint could theoretically be separated or sorted. However, this would require energy input, which would effectively mean that by decreasing the entropy of the paint (increasing the order by sorting the paint molecules into red and blue), the total entropy of the system, which would include the source of energy such as hydrocarbon fuel employed to sort the paint, would still have a net increase. The decreased entropy of the red and blue paint would be accompanied by an increase in entropy of the energy source(s), resulting in an overall increase in system entropy.

Penrose uses the Second Law of Thermodynamics to visit the origin of the universe, and to propose an alternate to the “Big Bang” theory. He also explores the end of the universe, as the total entropy of the universe becomes totally disordered as black holes, the greatest source of entropy in the universe, evaporate through “Hawking” radiation.

I persevered through the entire book, but at times I did skim and skip through some of the most technically challenging sections. I frequently found myself academically inadequate to fully understand and appreciate Penrose’s scientific concepts and explanations.

I regretfully cannot recommend * “Cycles of Time”* to any armchair science enthusiasts. Readers who have a high degree of physics and mathematical literacy will probably enjoy this book, but I doubt that any of these science experts follow my humble blog posts.

Frank T.