S1 - Brane Worlds and Cosmology |
Speaker_ |
Bludman, Sidney |
Talk _ |
Cosmological Acceleration: Dark Energy or Modified Gravity? |
Abstract _ |
The recently observed accelerating cosmological expansion or "dark energy" may be either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity) without any constituent Dark Energy. Low- or high-curvature modifications of Einstein gravity are distinguished by the spacetime (Ricci) curvature of their vacua. The dynamics of either kind of "dark energy" cannot be derived from the homogeneous expansion history alone, but the growth of cosmological fluctuations will potentially distinguish between static and "dynamic "dark energy". Dark Energy is epicyclic in character, requires fine-tuning, and cannot be detected in the laboratory or solar system. This, along with braneworld theories, now motivate searching for Dark Gravity on solar system, galaxy cluster and cosmological scales. |