Introduction; 1. Exact and inexact solutions of the Einstein field equations G. F. R. Ellis; 2. Inertial forces in general relativity M. A. Abramovicz; 3. Relativistic radiation hydrodynamics A. M. Anile and V. Romano; 4. Relativistic gravitational collapse J. Miller; 5. The cosmic censorship hypothesis C. J. S. Clarke; 6. The Kerr metric: a gateway to the roots of gravity? F. de Felice; 7. Galactic astronomy since 1950 J. J. Binney; 8. Galaxy distribution functions W. C. Saslow; 9. Nonlinear galaxy clustering B. J. T. Jones; 10. Quasars: progress and prospects M. J. Rees; 11. Decaying neutrinos in astronomy and cosmology D. W. Sciama; 12. Cosmological principles J. D. Barrow; 13. Anisotropic and inhomogeneous cosmologies M. A. H. MacCallum; 14. Mach's principle and isotropic singularities P. K. Tod; 15. Implications of superconductivity in cosmic string theory B. Carter; 16. The formation and evaporation of primordial black holes B. J. Carr; 17. Evaporation of two dimensional black holes S. W. Hawking; 18. Topology and topology change in general relativity G. W. Gibbons; 19. Decoherence of the cluttered quantum vacuum D. J. Raine; 20. Quantum nonlocality and complex reality R. Penrose; 21. The different levels of connections between science and objective reality N. Dallaporta.