Singularities in any physical theory are either remarkable indicators of the unknown
underlying fundamental theory, or indicate a change in the description of the physical reality …

Our aim is to propose a theory which goes beyond the classical formulation of
thermodynamics. This is achieved by enlarging the space of basic independent variables …

Beyond Einstein's Gravity is a graduate level introduction to extended theories of gravity and
cosmology, including variational principles, the weak-field limit, gravitational waves …

Nature's simplest field, the scalar field, has been the protagonist of physical theories for a
long time. Even before the publication of the theory of general relativity G. Nordström …

We use the language of squeezed states to give a systematic description of two issues in
cosmological particle creation:(a) Dependence of particle creation on the initial state …

We discuss the generalization to curved spacetime of a path-integral formalism of quantum
field theory based on the sum over paths first going forward in time in the presence of one …

This is the first of a series of papers which describe the functional-integral approach to the
study of the statistical and kinetic properties of nonequilibrium quantum fields in flat and …

Recent cosmological observations have posed a challenge for traditional theories of gravity:
what is the force driving the accelerated expansion of the universe? What if dark energy or …

Modified gravity theories with geometry-matter coupling, in which the action is an arbitrary
function of the Ricci scalar and the matter Lagrangian [f (R, L m) gravity], and of the Ricci …

The relevance is discussed of the initial value structure of the cosmological problem for
inflationary explanations of its present structure. Existing proofs of the cosmic “no hair” …