Open universes and avoidance of the cosmological singularity

Open-Flux Solutions to the Constraints for Plane Gravity Waves

OPERA and the GPS

Operadic curvature as a tool for gravity

Operating LISA as a Sagnac interferometer

Operational indistinguishabilty of doubly special relativities from special relativity

Operative Time Definition and Principal Uncertainity

Operator ordering and consistency of the wavefunction of the Universe

Operator ordering for generally covariant systems

Operator Spin Foam Models

OPERATOR WEAK VALUES AND BLACK HOLE COMPLEMENTARITY

Operators for quantized directions

Oppenheimer-Snyder Collapse in Moving-Puncture Coordinates

Oppenheimer-Volkoff Equation in Relativistic MOND Theory

Opportunities for Probing Fundamental Gravity with Solar System Experiments

Opportunity to Test non-Newtonian Gravity Using Interferometric Sensors with Dynamic Gravity Field Generators

Optical activity induced by curvature in a gravitational pp-wave background

Optical Anisotropy of Schwarzschild Metric within Equivalent Medium Framework

Optical caustics of Kerr spacetime: the full structure

Optical cavities as amplitude filters for squeezed fields