Energy: the subtle concept – Jennifer Coopersmith ****

There are many reasons why, by rights, this shouldn’t be a great popular science title. Physicist Jennifer Coopersmith makes clear at the very beginning that a background in the physical sciences is assumed for parts of the book. We have quite a few equations, and throughout the book Coopersmith does not hesitate to mention such words as tensors, integrals and vectors, with little in the way of definitions for the layperson. In addition, there is a lot packed in here – at 360 pages, whilst there are certainly longer books out there, I wondered when starting the book whether the non-specialist might suffer from information overload.

And yet, the more I read this book, the more difficult it was to put it down, and I was always excited about returning to it. (To give some indication of how much I enjoyed the book: I am often unable to get down to reading until 8 or 9 o’clock at night during the week, because of a long commute. For this book, however, I got up especially early on one occasion to continue reading so I didn’t have to wait until the evening.) This is because, despite all the shortcomings mentioned above, the book also has a fascinating story to tell about the development of our understanding of energy as a physical quantity, and overall, the way Coopersmith describes this development means that these shortcomings, while never going away, become less significant.

We begin with Liebniz’s concept in the 17th century of vis viva, or ‘live force’, defined as some kind of ‘activity’ that was conserved and which was ‘the cause of all effect in the universe.’ After tracing developments in the 18th and 19th centuries, we go on to consider our modern understanding of kinetic and potential energy, via discussions of quantum mechanics (where we find that, contrary to what we had believed, the principle of conservation of energy can be violated due to the uncertainty principle) and relativity (a consequence of which is that we understand energy as being interchangeable with mass). Along the way, we meet a varied cast of characters who have contributed to our understanding of energy, and the biographical sections we get on the scientists involved complements well the explanations of the science, and makes the book, on the whole, very readable. Particularly interesting is the section on Sadi Carnot.

It is also the case that, whilst the science can often be challenging, if you put in the effort you will be more than compensated for your trouble, and it is possible to get real insights into the nature of energy, which, unlike less abstract physical quantities like mass or momentum, can be difficult to get a feel for. Yes, there are equations, and yes, there are tricky concepts which could have been introduced more gently. But if you persevere, and continue reading where you may otherwise be liable to get a little stuck, it is worth it, and you always get, at the very least, a good idea of the big picture.

I can’t completely overlook the drawbacks mentioned above, so am unable to give the book the full five stars. But I would still highly recommend this. Although perhaps ideal for physics undergraduates, this book is still of great value for the layperson, who would be likely to get a lot out of it.

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Review by Matt Chorley