Relativistic gravity and some astrophysical applications

These lectures are intended to provide an overview of gravitation theory and a framework for various applications. We will first discuss the foundations and structure of metric theories of gravity, developed from the consequences of various extremal action principles. Then we restrict our consideration to scalar-tensor theories of gravity, and introduce various astrophysical applications. The weak-field applications are the index of refraction of gravity and gravitational waves. The strong-field applications are compact objects, their surrounding particle orbits, and cosmology. Except for waves and cosmology, effects of the scalar field are assumed negligible, reducing the theory to general relativity. (author)