BOLTZMANN'S ATOM tells the story of the crucial scientific struggle over the existence of the atom during the second half of the 19th century. This struggle was a turning point in the history of the modern world. It would never have happened without the forgotten genius of Ludwig Boltzmann, a 19th century Austrian theoretical physicist who had a string of deeply profound insights primarily into the physical nature of heat, but also gas, matter, and, in fact, literally everything. In 1850 no university taught such a subject as theoretical physics, but by 1900 it was a fully fledged discipline with whole institutes devoted to it. This burgeoning scientific movement led within just a few years to the discovery of quantum mechanics by Max Planck, radioactivity by Marie Curie, general relativity by Albert Einstein, the uncertainty principle by Werner Heisenberg, and more recently quantum electodynamics by Richard Feynman, the quark by Murray Gell-Mann, and even up-to-the minute developments in chaos and superstring theory. Indeed, as David Lindley shows, Boltzman's brilliant insights brought about the golden age of physics that we continue to live in today. David Lindley frames his story with the long running debate between Boltzmann and Ernst Mach who held that theoretical physics was completely misguided. Mach's memorable line in 1900 "I don't believe atoms exist" is where the book begins.