This up-to-date survey of the interplay between gravity and particle physics theory contains treatments of cosmological perturbations, trans-Planckian problems in cosmology, the cosmological basis in a framework of projective unified field theory, atom interferometry in black holes and the early universe and semiclassical gravity. There are also discussions of spinorial matter in affine theory of gravity, the phase problem and Mach's principle, a Hamiltonian formulation of gravitational theory, and spin fluctuations. A special section covers Dirac geometry and real space-time, Dirac wave functions and black holes, properties of black hole solutions, black hole spectroscopy and thermodynamics. The emphasis is on observational aspects and in this context there are discussions of attempts to measure Newtonian G, the stability of G and multidimensional gravitational models, improved measurements and the experimental limit of G-dot, past results and new experimental tests for violation of the principle of equivalence, signals observed with a detector having 20<SUP>21</SUP> intrinsic spins, virtual graviton exchange consistent with constant G and the weak equivalence principle. There is an update on neutrino oscillations and the helicity precession of fermions in gravitational / inertial fields.