Darker Side of the Universe

Abstract

Observations suggest that nearly seventy per cent of the energy density in the universe is unclustered and exerts negative pressure. Theoretical understanding of this component (`dark energy'), which is driving an accelerated expansion of the universe, is {\it the} problem in cosmology today. I discuss this issue with special emphasis on the cosmological constant as the possible choice for the dark energy. Several curious features of a universe with a cosmological constant are described and some possible approaches to understand the nature of the cosmological constant are discussed.

Invited Review Talk at the 29th International Cosmic Ray Conference, Aug 3-10, 2005, Pune, India; to appear in the proceedings; 15 pages; 2 figures

Cited by in corpus (4)

• Physical vacuum as a system manifesting itself on various scales - from nuclear physics to cosmology
• The de Broglie universal substratum, the Lochak monopoles and the dark universe
• The nature of cosmological singularities in isotropic universes and braneworlds
• Vacuum Energy Problem, Fundamental Length and Deformed Quantum Field Theory