Dark Energy Dichotomies: Observational signatures of matter and gravity based theories.

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AST-0607018BeanA fundamental conundrum exists as to whether the observed accelerating expansion of the Universe requires a modification to the theory of gravity (Einstein's General Relativity), or is due to the additional energy density of a novel type of matter (dark energy). This research program will confront this dichotomy, and establish a complement of observational strategies and precise theoretical descriptions to differentiate the competing dark energy mechanisms. By establishing the linear and non-linear perturbation evolution for various modified gravity theories, and for clustering dark energy, this study will show if, and how, various statistical measures can distinguish between various choices. This will show whether current data are adequate to the task, and guide future surveys by using simulated datasets.The research includes student training, cross-disciplinary interactions with string theorists and gravitational physicists, and various avenues for communicating with the general public.