Quantum Physics: new book published by Barnes and Noble
From light and matter to time and space… in the last 100 years, there has been a revolution in the way physicists understand almost everything. Why? Well, at the most fundamental level of existence – on the quantum scale of subatomic particles and forces – nothing works according to familiar rules of mechanics, electromagnetism, or thermodynamics. Particles appear in places they should not be able to reach. Quantum objects become entangled and always maintain a spooky bond. Cats can be alive and dead at the same time. The question of whether something is a wave or a particle is answered simply: ‘yes’.

In my new book Quantum Physics, published in the United States by Barnes and Noble, I explore the theories developed by scientists grappling with the counterintuitive quantum world. The book’s chapters seek to introduce quantum concepts thematically:
Chapter 1, clues before quantum physics, looks at the nature of light, and the phenomena that classical physics couldn’t explain. Although the famous double slit experiment showed light behaved as a wave, the notion emerged that nature might not be continuous, but exist in discrete chunks or quanta.
Chapter 2, quantum theory develops, looks at the early 20th-century revolution in understanding the minuscule subatomic scale at which quantum phenomena occur. Erwin Schrodinger formulated his equation, using a wave function to describe a quantum system’s multiplicity of states – like a cat that could be alive and dead at the same time.
In chapter 3, quantum chemistry, we meet the idea of quantum numbers: four properties, including quantum spin, that uniquely describe each electron in an atom. The Pauli Exclusion Principle explains why electrons are organised in pairs in atomic orbitals – and how this leads to all of the electron reactions that constitute chemistry.
Chapter 4, particle physics, reveals the Standard Model, which now incorporates 17 quantum particles including quarks, leptons and gauge bosons that mediate four fundamental forces. This has been pieced together through theory (including the prediction of antimatter and the Higgs boson) and experiments (in particle colliders as well as with cosmic rays).

Quantum calculations is chapter 5, and it presents the idea of quantum entanglement – the idea that two particles can be linked in such a way that they affect each other even at vast distances – and how it is leading us to be able to teleport particles, encrypt information, and develop incredibly fast quantum computers.
In chapter 6, quantum physics in nature, we meet the phenomenon of quantum tunnelling, in which a quantum particle described by a wave function has a non-zero probability of crossing a classically impossible barrier. It emerges that natural systems in plant biology, human physiology, stellar physics, and much more, are reliant on tunnelling.

Chapter 7, quantum reality, allows some time to think about the philosophical interpretations of quantum physics, which are still under debate, and the strange fact that the outcome of certain quantum experiments depends on the observer. Are there many worlds? Is time reversible? How do single electrons still produce an interference pattern?
Chapter 8, quantum technology, looks at the many current applications of quantum properties in everyday life. LEDs, transistors, quantum dots, lasers, atomic clocks, scanners and microscopes all feature, plus the potential of superconductors using quantum particles. Quantum 2.0 is the advent of ideas like quantum annealing, which exploits quantum phenomena to optimise systems.
Quantum future is chapter 9, and this section examines the remaining mysteries in quantum physics. They include the problem of explaining how the force of gravity fits within the theoretical framework, and what dark matter and dark energy might be. Black holes and holographic information may reveal the true nature of quantum reality.
Scientists hope that quantum physics will ultimately allow the formulation of a Theory of Everything that accounts for all the universe’s physical phenomena.
The text of the book benefitted from many insightful comments and improvements from Dr Philip Pratt, for which I am supremely grateful. Through the words, and the abundant diagrams and illustrations created by Wayne Blades, I hope readers will be able to enjoy the ideas and impact of quantum physics on the world we know now.
With many thanks to the editors involved in this project.