---

This book presents the Projective approach to de Sitter Relativity. It traces the development of renewed interest in models of the universe at constant positive curvature such as "vacuum" geometry. The De Sitter Theory of Relativity, formulated in 1917 with Willem De Sitter´s solution of the Einstein equations, was used in different fields during the 1950s and 1960s, in the work of H. Bacry, J.M. LevyLeblond and F.Gursey, to name some important contributors. From the 1960s to 1980s, L. Fantappié and G. Arcidiacono provided an elegant group approach to the De Sitter universe putting the basis for special and general projective relativity. Today such suggestions flow into a unitary scenario, and this way the De Sitter Relativity is no more a "missing opportunity" (F. Dyson, 1972), but has a central role in theoretical physics. In this volume a systematic presentation is given of the De Sitter Projective relativity, with the recent developments in projective general relativity and quantum cosmology.

---

De Sitter Relativity: A Sixty-Year-Long Story.- Steps Towards the de Sitter Relativity.- Projective Special Relativity.- Point, Fluid and Wave Mechanics.- Cosmic Electromagnetism.- Projective General Relativity (PGR).

---

Ignazio Licata, born 1958, is an Italian theoretical physicist, professor and scientific director of the Institute for Scientific Methodology, Italy. He worked on quantum field theory, interpretation of quantum mechanics, and recently quantum cosmology. His further topics of research include the
foundation of quantum mechanics, space-time at Planck scale, the group approach in quantum cosmology, systems theory, non-linear dynamics, as well as computation in physical, biological and cognitive systems (logical openness, sub and super Turing systems). Licata has developed a new approach to quantum cosmology ("Archaic Universe") based on de Sitter invariant special relativity.

Leonardo Chiatti, born in 1960, graduated in physics at Rome University "La Sapienza" in 1985, discussing a thesis on spin in stochastic mechanics under the guide of Marcello Cini. His interest focus on the conceptual foundations of quantum mechanics and their relation to areas as quantum dissipative phenomena, quantum cosmology and the spectrum of elementary particles. During ´90s, he was involved in MQC Project aiming to produce superpositions of quantum states in mesoscopic systems (rf-SQUIDs). Successively, his interest enlarged to medical physics and currently he serves as physicist in chief at AUSL Medical Physics Laboratory in Viterbo, Italy.

Along the past decade he has been, in collaboration with Ignazio Licata, a proponent of de Sitter quantum cosmology.

Elmo Benedetto was born in Salerno January 2, 1972. He graduated and later he received his Phd from Salerno University. At present he is a member of the physics research group at Benevento University. Main research interests areas are Cosmology and relativistic physics.

---