A Broader View of Relativity: General Implications of Lorentz And Poincare Invariance, 2nd Edition by Jong-Ping Hsu

"A Broader View of Relativity" shows that there is still new life in old physics. The book examines the historical context and theoretical underpinnings of Einstein's theory of special relativity and describes Broad Relativity, a generalized theory of coordinate transformations between inertial reference frames that includes Einstein's special relativity as a special case. It shows how the principle of relativity is compatible with multiple concepts of physical time and how these different procedures for clock synchronization can be useful for thinking about different physical problems, including many-body systems and the development of a Lorentz-invariant thermodynamics. Broad relativity also provides new answers to old questions such as the necessity of postulating the constancy of the speed of light and the viability of Reichenbach's general concept of time. The book also draws on the idea of limiting-four-dimensional symmetry to describe coordinate transformations and the physics of particles and fields in non-inertial frames, particularly those with constant linear accelerations. This new edition expands the discussion on the role that human conventions and unit systems have played in the historical development of relativity theories and includes new results on the implications of broad relativity for clarifying the status of constants that are truly fundamental and inherent properties of our universe.