Claudius Ptolemy (about 100–170 CE) lived in Alexandria, Egypt, part of the Roman Empire. A mathematician, geographer and astrologer, his famous book on astronomy codified the ancient view of the universe, with the sun and observable planets orbiting around the earth. This geocentric perspective was succeeded 1400 years later by the work of Copernicus who determined that the earth and other planets of the solar system revolve around the sun. Christián C. Carman (introduction) is professor and researcher at the Universidad Nacional de Quilmes, Argentina, and research member of the National Research Council of Argentina (CONICET). He works on topics related to philosophy of science as well as history of ancient astronomy (mainly related to the Antikythera Mechanism, Aristarchus of Samos and Ptolemy), and history of Early modern astronomy. Professor Marika Taylor (Series Foreword) is a Professor of Theoretical Physics and Head of School within Mathematical Sciences at the University of Southampton. Her research interests include all aspects of string theory, gravitational physics and quantum field theory. In recent years much of her work has been focused on holographic dualities and their implications. Marika's research has featured in such publications as Physical Review, Journal of High Energy Physics and General Relativity and Gravitation among others.