Explaining the origin of life with physics

Claire Malone reviews Molecular Storms: the Physics of Stars, Cells and the Origin of Life by Liam Graham

Can you explain the origin of life on Earth using the principles of thermodynamics and statistical mechanics? It’s not a question that even physics students see in their more challenging assignments. But it is one that Liam Graham – physicist turned economist – attempts to answer in his debut book Molecular Storms: the Physics of Stars, Cells and the Origin of Life.

Throughout Molecular Storms, Graham uses a light, informal tone with a measured injection of humour to keep readers on a direct path from the laws of thermodynamics to the inception of biological diversity. He begins by painting a picture of the motions of molecules in the “molecular storm”. The opening chapters acquaint the reader with the main tenets of statistical mechanics (such as microstates and Brownian motion) as well as, of course, thermodynamics.

Graham clearly explains that the entropy (disorder) of a closed system is destined to increase, and describes in detail the operation of heat engines, motors and their lesser-known cousin, ratchets. Other blockbuster principles of physics – such as Noether’s theorem (which relates conservation laws to symmetries in nature) and quantum superposition – are also introduced in passing, more in the form of acknowledgement than explanation.

Graham continues with an examination of the prerequisites of life. The physics groundwork that he’s laid lets him explore how the formation of planets, the action of enzymes and the biological processes essential to the functioning of cells can all be understood in terms of the thermodynamical concepts of ratchets and heat engines.

This section is supported by a brief but clear detour into how mixtures of molecules are driven to chemical equilibrium by the molecular storm. The diversion into chemistry is necessary for the reader to follow the lengthy discussion in the next few chapters about the reactions of compounds, which play a central role in the metabolism of cells. The book ends with a detailed discussion of the thermodynamics that would have been key to the production of organic molecules and the environment of the newly formed Earth, like hydrothermal vents and ponds.

As someone with a pure physics background, I was tempted to refer to other sources to fully understand the more biology-heavy chapters. Still, there is enough detail for the reader to comfortably follow the general direction of the book’s argument. But given the virtual impossibility of explaining every relevant process of such a complex subject in detail – while still entertaining and holding the reader’s attention – Graham includes lots of well-researched suggestions for further reading and links to relevant research papers.

Which “hard problem”?

Graham’s career, characterized by a journey across various disciplines including physics, philosophy and economics, is reflected in the structure of his book. This blend of different fields might be why Molecular Storms is such an engaging read. The strong undertone of statistical mechanics throughout the narrative undoubtedly owes its origin to his first degree in theoretical physics from the University of Cambridge.

But Graham also draws on his background in philosophy to address the puzzle of the origin of life, referring repeatedly to the concept of a “Boltzmann brain” – that is, the idea that random fluctuations of matter could give rise to consciousness. In a similar vein, he explicitly demotes the “hard problem of consciousness” – which questions how physical matter gives rise to conscious and subjective experience – saying, “The origin of life is as complex a problem as there is (I suspect it will prove harder than the so-called ‘hard problem’ of consciousness).”

Molecular Storms is likely to appeal to readers on two levels. First, it can be seen as a fascinating guide for a reader with a general interest in physics, examining a physicist’s view of the emergence of life. This casual reader can enjoy the ride without needing to turn to the mathematical calculations outlined in the appendices.

This book is a good example of the interdisciplinary nature of scientific research, something that is often under-emphasized in undergraduate courses

Alternatively, an undergraduate student interested in this area would benefit from working through the calculations and following the explanations. This book is also a good example of the interdisciplinary nature of scientific research, something that is often under-emphasized in undergraduate courses. However, I would advise student readers to have other texts on hand unless they already have a very good conceptual grasp of the principles mentioned.

Indeed, both the casual reader and the student would benefit from referring to the online resources for illustrations of the concepts discussed, as the diagrams in the book are sometimes merely representative of the online content.

But as most Physics World readers are likely to fall into one of these categories, I would highly recommend that you add Molecular Storms to your reading list.

• 2023 Springer 291pp £29.99pb £23.99ebook