Theoretical Physical Cosmology at Berkeley

Theoretical physical cosmology considers the universe as a physical system, studying its contents and evolution. The universe is undergoing constant change due to several competing forces: on the largest scales, spacetime itself is expanding, while matter is collapsing due to gravity, with other forces such as electromagnetism coming into play as well. For the first time we seem to have an accounting of the contents of the universe (dominated by "dark energy", with a large amount of dark matter and maybe 4% in familiar matter). In addition, spectacular observations now have told us about conditions in the universe early on (given by the cosmic microwave background, CMB, anisotropies) and for an ever-growing set of systems (for example galaxy clusters, distributions of galaxies, and Lyman alpha systems) for different time frames up to the present.

This newly found knowledge has set the stage for new questions in the field. For example, we do not know what the dark energy and dark matter are, only what they do (gravitationally), their necessity in the current paradigm has prompted many tests to verify their presence and get insight into other properties. Likewise, structure formed from the initial seeds of the cosmic microwave background via gravitational collapse, however, we don't know how galaxies are distributed within larger clumps of matter or how they got that way. We are in an observational golden age, and combining these spectacular results with theoretical work (especially numerical simulation which has also progressed rapidly) is allowing us to find out what the universe is made of and how it got to be in the state it is today.

The puzzles are both directly theoretical (what does the paradigm predict and how can we calculate this, what do deviations look like) and more closely linked to observation (which measurements would isolate the quantities theorists can predict with the most reliability)? Much of our work requires numerical simulations to accurately include even the familiar gravitational force, as gravitational instability is nonlinear, however many of us also do analytical work too. Theoretical cosmologists in the TAC work closely with many of the observational cosmology groups at Berkeley and elsewhere, as this field offers a wonderful opportunity to confront theory and observation to advance both.

The theorists are members of the Berkeley Cosmology Group. Topics we study (along with some relevant experimental groups based on or with significant representation on campus or alongside,at LBNL) include:

Senior theoretical physical cosmologists at Berkeley include: J. Borrill , J. Cohn, M. Davis, E. Linder, C.-P. Ma, Eliot Quataert, M. White.

For more information on theoretical cosmology, see the pages of the above members, as well as other associated links here.


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