In Light after Dark II: The Large and the Small, Dr Francis explores the physics and the philosophy pertinent to the conceptual foundations of modern physical theory, avoiding equations and with sufficient explanation to be accessible to general readers. A comprehensive rationale is described for the theories of Einstein, Heisenberg, Dirac, von Neumann, Feynman, and others. Spacetime curvature is elucidated. The meanings of Schrödinger’s cat, Bell’s theorem and Bertlmann’s socks are explained. Implications for determinism, free will, and the nature of space and time are examined. This is a book of well-established but up-to-date science, focussing on the concepts behind the mathematics of modern physical theory and covering the special and general theories of relativity, relativistic quantum mechanics, and particle physics. It describes both what we know and how we know it, and explains the thought that underlies modern physics. It includes explanation as to how infinities and other undefined quantities can be avoided. Contrary to widespread belief, there are no unresolved paradoxes or inconsistencies in either relativity or quantum mechanics (either separately or together), but understanding them requires a willingness to let go of common misconceptions concerning the character of space, time, and spacetime. Light after Dark II will appeal to students of physics and philosophy and anyone interested in the workings of reality.