Jaroslav Zamastil is an Associate Professor of theoretical physics at Charles University in Prague, Faculty of Mathematics and Physics. He teaches courses on undergraduate quantum mechanics, quantum electrodynamics, and field-theoretical methods in many-body problems. He conducts research in atomic and mathematical physics, and has published about 30 original scientific papers. He is the author of two previous books, Quantum Mechanics and Electrodynamics (Springer, 2017, co-authored with Jakub Benda, and originally published in Czech by Karolinum, 2016) and Understanding the Path from Classical to Quantum Mechanics (Springer, 2023).