One of the most fundamental attributes of statistical mechanics is the promise to its practitioners that one need not ever compute the equations of motion for the individual particles of the system. This is important in diverse applications where either the interactions cannot be effectively modeled using pair-wise interactions or simply because the interactions are unknown. Using the concept of the peculiar velocity field provides the advantage of postponing the need to understand the interactions between the particles that comprise the system. The peculiar velocity appears whenever there exists a collection of objects with each object possessing an individual motion distinct from all others and derived from the interaction of any one object with other objects both within and beyond the collection. This book presents an analysis of the peculiar velocity as a vector field and applies this concept to problems in astrophysics, nuclear physics and economics. This invaluable instruction is to be read by graduate students in science and engineering as well as professionals in the field. Steve Grisafi has been writing engineering and applied science journal articles for 24 years. An alumnus of Rensselaer Polytechnic Institute and Yale University, Steve earned his PhD in chemical engineering at Columbia University in the City of New York. Steve grew up on Long Island, New York, and now resides in Easton, Pennsylvania.Publisher's website: http://www.eloquentbooks.com/PeculiarVelocityInAction.html