This book on the striking phenomenon of the asymmetry of natural phenomena with respect to time reversal presents some of the most important classes of physical processes characterizing the arrow of time, and strives to uncover its common cosmological root. In reviews this book has been unanimously praised by both physicists and philosophers of science. This thoroughly revised and enlarged third edition will be welcomed by both students and specialists.

This book has been thoroughly revised to include important new results. At the same time it retains the features that make it a classic text on irreversibility.

1. The Physical Concept of Time.- 2. The Time Arrow of Radiation.- 3. The Thermodynamical Arrow of Time.- 4. The Quantum Mechanical Arrow of Time.- 5. The Time Arrow of Spacetime Geometry.- 6. The Time Arrow in Quantum Cosmology.- Epilog.- Appendix: A Simple Numerical Toy Model.- References.