Maurizio Gasperini is Professor of Theoretical Physics at the Physics Department of the University of Bari, Italy. He is the author of 150 publications on gravitational theory, high-energy physics, and cosmology, and has twice won an "Award for Essays on Gravitation" from the Gravity Research Foundation (1996 and 1998). His former posts include a permanent position in the Department of Theoretical Physics at the University of Turin, and two appointments as Scientific Associate at CERN, Theory Division (1993 and 1996). Here, in collaboration with Gabriele Veneziano, he formulated and developed an early-cosmology scenario based on the symmetries of string theory.

General Relativity and Standard Cosmology.- String Theory, Duality, And The Primordial Universe.- The Theory of Strings.- Inflation and the Birth of the Universe.- The Cosmological Background of Gravitational Radiation.- Other Relics of the Primordial Universe.- Quantum Cosmology.- The Future of our Universe.- Recent Developments: Brane Cosmology Scenarios.- Conclusion.

Terms such as "expanding Universe", "big bang", and "initial singularity", are nowadays part of our common language. The idea that the Universe we observe today originated from an enormous explosion (big bang) is now well known and widely accepted, at all levels, in modern popular culture. But what happens to the Universe before the big bang? And would it make any sense at all to ask such a question? In fact, recent progress in theoretical physics, and in particular in String Theory, suggests answers to the above questions, providing us with mathematical tools able in principle to reconstruct the history of the Universe even for times before the big bang.

In the emerging cosmological scenario the Universe, at the epoch of the big bang, instead of being a "new born baby" was actually a rather "aged" creature in the middle of its possibly infinitely enduring evolution. The aim of this book is to convey this picture in non-technical language accessibile also to non-specialists. The author, himself a leading cosmologist, draws attention to ongoing and future observations that might reveal relics of an era before the big bang.