Kevin Orrman-Rossiter Reviews Mass: the quest to understand matter from Greek atoms to quantum fields

Mass: the quest to understand matter from Greek atoms to quantum fields by Jim Baggott

Mass is a commonplace idea, and possibly the one physics concept that we would all lay some claim to understanding. As Jim Baggott says it is hardly mysterious, we come to grips with it standing on the bathroom scales, or lifting ‘weights’ in the gym, or trying to shift that heavy object. It is surely just the amount of matter in these things. And there lies the problem and the basis of this book; what is matter made of and why does it have a property we call mass? In this entertaining and stimulating book science writer, Jim Baggott, takes us on the quest to find the answers to this simple question.

But wait. Is a book on ‘mass’ needed? It would seem reasonable that any physics text will have a definition that we can get along with. A quick look at a classic, the Feynman Lectures in Physics, though highlights the problem. In section 9.1 the Nobel laureate Feynman introduces us to mass via Galileo’s principle of inertia, where mass is used as a quantitative measure of inertia. We can measure mass, Feynman explains, by swinging an object in a circle at a certain speed measuring how much force we need to keep it in the circle. What we have are quantitative relations to gravity, momentum and forces – all of which relate to our perceptions in the gym and on the bathroom scales above. With effort, we can master this classical concept of mass, historically thanks to Galileo and Isaac Newton. But we are no closer to answering our fundamental question. Few if any physics texts will tackle this question. This was recognised by physicist Max Jammer who in 1961 wrote Concepts of mass in classical and modern physics, a dense (pun intended) erudite book that won a prize from the American Academy of Arts and Sciences as “the notion of mass had never been given an integrated and coherent historical investigation until publication of this book.” Jammer followed this up in 2000 with Concepts of mass in contemporary physics and philosophy. These are the benchmark, but they are graduate level texts – and on the equations level they average out at greater than an equation per page – a daunting task for any but the most scholarly of readers. So, there is a gap that Jim Baggott fills nicely with Mass.

Jim Baggott is well up to the task. A freelance writer and former university lecturer in chemistry and industry researcher Baggott has written several “science for interested readers” books, I have been particularly impressed by those on the quantum story (2011) and the ‘Higgs’ particle (2013). In Mass: the quest to understand matter from Greek atoms to quantum fields he takes the reader historically through our many concepts of mass. This is deftly done as there are times when it is easy to be side-tracked by the shifting ideas about what is matter – particularly with the rise of quantum physics and then field theory and the standard model – but Baggott steers this back to the central question of mass.

Without spoiling Baggott’s story, I found his concluding chapter “Mass without mass” to be a great example of his writing in Mass. In this he brings us to the question of matter – via a familiar and everyday substance – frozen water, an ice-cube. He asks “What is this cube made of? What is responsible for its mass? Using this simple example, he recaps and brings to a prosaic conclusion what is an enthralling, philosophically deep and scientifically rich, story.

Each chapter concludes with a welcome touch, a summary ‘five things we have learned’, providing way stations to refer to and pointers of where the next chapter will start. These in addition to sufficient, but non-intrusive endnotes, a glossary, and bibliography position the book well for the curious reader, satisfying and substantive but providing a tantalizing starting point for more to explore. A highly-recommended read.

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Kevin Orrman-Rossiter

Kevin Orrman-Rossiter is a freelance science writer and reviewer. His writing has features in COSMOS magazine, Books&Publishing, and online on Australian Science lucid thoughts and dragon laughing . Originally studying physics, Kevin had a successful research career, reaching the heady heights of an ARC Queen Elizabeth II Fellow, then after being lured into the fascinating world of industry research, he ended up some years later, in marketing and strategy. When not writing, reviewing, or reading books to review, Kevin is now found; forming links between Australian industry and researchers at the University of Melbourne, reading (what a lovely quaint term) History & Philosophy of Science at University of Melbourne, and, in defiance of ageing