Perturbations of black holes, initially considered in the context of possible observations of
astrophysical effects, have been studied for the past 10 years in string theory, brane-world …

This book is an attempt to simplify and clarify the language we use to express ideas about
space and time. It was motivated by the belief that such is an essential step in the endeavor …

Massive bosonic fields of arbitrary spin are predicted by general extensions of the standard
model. It has been recently shown that there exists a family of bimetric theories of gravity …

We investigate the instability of the massive scalar field in the vicinity of a rotating black hole.
The instability arises from amplification caused by the classical superradiance effect. The …

Bosonic fields on rotating black hole spacetimes are subject to amplification by
superradiance, which induces exponentially-growing instabilities (the “black hole bomb”) in …

A new gauge theory of gravity is presented. The theory is constructed in a flat background
spacetime and employs gauge fields to ensure that all relations between physical quantities …

We study the propagation of a massive vector or Proca field on the Schwarzschild
spacetime. The field equations are reduced to a one-dimensional wave equation for the odd …

The field of a massive vector boson in the vicinity of a rotating black hole is known to suffer
an instability, due to the exponential amplification of (corotating, low-frequency) bound state …

Astrophysical black holes are generally surrounded by accretion disks, galactic matter and
the omnipresent cosmic microwave background radiation, thus allowing for the concurrent …

Superradiance is a process by which massive bosonic particles can extract energy from
spinning black holes, leading to the build up of a condensate if the particle has a Compton …