Ultrarelativistic black hole in an external electromagnetic field and gravitational waves in the Melvin universe
Ultrarelativistic boost of spinning and charged black rings
Ultrarelativistic boost of spinning black rings
Ultrarelativistic boost of the black ring
Ultrarelativistic circular orbits of spinning particles in a Schwarzschild field
Ultrarelativistic fluid dynamics
Ultrarelativistic limits of boosted dilaton black holes
Ultrarelativistic Motion: Inertial and Tidal Effects in Fermi Coordinates
Ultrarelativistic sources in nonlinear electrodynamics
Ultrastatic spacetimes
Ultraviolet behavior in background independent quantum field theory
Ultraviolet Complete Quantum Gravity
Ultraweak excitations of the quantum vacuum as physical models of gravity
Un-modeled search for black hole binary systems in the NINJA project
Unambiguous angular momentum of radiative spacetimes and asymptotic structure in terms of the center of mass system
Unambiguous determination of gravitational waveforms from binary black hole mergers
Unambiguous Quantum Gravity Phenomenology Respecting Lorentz Symmetry
Unambiguous spin-gauge formulation of canonical general relativity with conformorphism invariance
Unboundable Spacetimes with Metric Singularities and Matching Metrics and Geodesics: A Black-White Hole and a Big Crunch-Bang
Unboundedness of Triad -- Like Operators in Loop Quantum Gravity