ALTERNATIVE THEORIES OF GRAVITY

By R. ELVIY

CONTENTS INTRODUCTION EXTENDED THEORIES OF GRAVITY ACTIONS AND FIELD EQUATIONS SCALAR-TENSOR THEORIES FOURTH-ORDER THEORIES CONFORMAL TRANSFORMATIONS HOMOGENEOUS AND ISOTROPIC SCALAR-TENSOR COSMOLOGIES FRIEDMANN-ROBERTSON-WALKER COSMOLOGIES BRANS-DICKE THEORY RADIATION DOMINATION MATTER DOMINATION VACUUM ENERGY DOMINATION VACUUM SOLUTIONS MORE GENERAL THEORIES VACUUM DOMINATION HOMOGENEOUS AND ISOTROPIC FOURTH-ORDER COSMOLOGIES FREIDMANN-ROBERTSON-WALKER COSMOLOGIES THE DYNAMICAL SYSTEMS APPROACH LOCATING THE CRITICAL POINTS STABILITY OF THE CRITICAL POINTS ILLUSTRATION OF THE PHASE PLANE OTHER HOMOGENEOUS FOURTH-ORDER COSMOLOGIES G¨ODEL, EINSTEIN AND DE-SITTER UNIVERSES G¨ODEL UNIVERSES EINSTEIN STATIC UNIVERSES DE SITTER UNIVERSES ANISOTROPIC COSMOLOGIES FIELD EQUATIONS EXACT SOLUTIONS INVESTIGATION OF THE E?ECTS OF MATTER DISCUSSION STATIC SOLUTIONS DYNAMICAL SYSTEM LINEARISED SOLUTION INHOMOGENEOUS COSMOLOGICAL SOLUTIONS SPHERICAL COLLAPSE MODEL A MORE RE?NED SPHERICAL COLLAPSE MODEL EXACT SOLUTION LINEAR PERTURBATION ANALYSIS SCALAR-TENSOR COSMOLOGIES WITH ENERGY EXCHANGE TRANSFER OF ENERGY AND ENTROPY GENERAL SOLUTIONS PARTICULAR SOLUTIONS BEHAVIOUR OF SOLUTIONS PHYSICAL CONSEQUENCES COSMOLOGICAL CONSTRAINTS SCALAR-TENSOR THEORIES AND PRIMORDIAL NUCLEOSYNTHESIS MODELLING THE FORM OF G(T) THE E?ECT OF A NON-CONSTANT G CONSTRAINING THE THEORY PRIMORDIAL NUCLEOSYTHESIS MICROWAVE BACKGROUND FORMATION 10 WEAK-FIELD CONSTRAINTS 10 1 PARAMETERISED POST-NEWTONIAN APPROACH 10 2 SCALAR-TENSOR THEORIES 10 3 FOURTH-ORDER THEORIES 10 3 1 STATIC SPACE-TIME 10 3 2 NON-STATIC SPACE-TIME 11 CONCLUSIONS