MG12 - Talk detail
 

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Abstract

Quantum vacuum effects from boundaries of designer potentials

Vacuum energy in quantum field theory, being the sum of zero-point energies of all field modes, is formally infinite but yet can give rise to finite observable effects. One way of understanding how these effects arise is to compute the vacuum energy for a large cavity divided into disjoint regions by pistons. In this talk I will describe such a calculation in a situation where the field potential is not the same in all regions of the cavity. The observable parts of the vacuum energy in such cases can depend on the geometry (shape) of one region of the cavity and can be large when this region is too. This unusual behavior may be interesting for studies on the relation between vacuum energy in quantum field theory and geometry. This talk will be based on: Phys. Rev. D 79, 085012 (2009), arXiv:0904.0527 [hep-th]

Static Isotropic Spacetimes with Radially Imperfect Fluids

When solving the equations of General Relativity in a symmetric sector, it is natural to consider the same symmetry for the geometry and stress-energy. This implies that for static and isotropic spacetimes, the most general natural stress-energy tensor can be written as a sum of a perfect-fluid and a radial imperfect-fluid component. In the special situations where the perfect-fluid vanishes or describes a cosmological constant, the solutions to Einstein's equations can be thought of as modified Schwarzschild and Schwarzschild-de Sitter spaces. I will describe the geometric properties of these solutions, summarize how solar-system observations constrain the magnitude of the imperfect-fluid component, and mention under what circumstances this component can describe dark-matter-like effects.

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