I review the problem of dark energy focussing on cosmological constant as the candidate
and discuss what it tells us regarding the nature of gravity. Section 1 briefly overviews the …

This book concerns the foundations of Quantum Gravity, in particular from a conceptual point
of view. It provides a self-contained introduction to this topic, resting on particular features of …

These are the author's lectures at the 1992 Les Houches Summer School," Gravitation and
Quantizations". They develop a generalized sum-over-histories quantum mechanics for …

We derive corrections to the Schrödinger equation which arise from the quantization of the
gravitational field. This is achieved through an expansion of the full functional Wheeler …

Nearly seventy per cent of the energy density in the universe is unclustered and exerts
negative pressure. This conclusion--now supported by numerous observations--poses the …

We read in order to know we are not alone, I once heard, and perhaps it could also be
suggested that we write in order not to be alone, to endorse, to promote continuity. The idea …

Despite many efforts in the last sixty years there does not yet exist a consistent theory of
quantum gravity. Why, then, should one address an issue like the semiclassical …

We revisit the calculation of quantum-gravitational corrections to the power spectra of scalar
and tensor perturbations in the Born-Oppenheimer approach to quantum gravity. We focus …

We treat the interaction of a semiclassical electromagnetic field with a complex scalar field
as a continuous measurement process through which certain interference terms between …

We make a critical review of the semiclassical interpretation of quantum cosmology and
emphasise that it is not necessary to consider that a concept of time emerges only when the …