#### Gravitation and Cosmology

General Relativity — Einstein’s theory of gravity — predicts many spectacular phenomena, such as black holes and gravitational lensing, and provides the basis to our understanding of the Universe and its evolution at the largest scales. The standard cosmological model has been developed into a very accurate theory of the dynamics of the Universe, both at the largest observable distances and back in time to almost its very beginning. Especially intriguing is the discovery, made around the turn of the millenium, that the expansion of the Universe is not slowing down but accelerating. This hints at the possible existence of an unknown "dark energy" which fills the universe with negative pressure.
[+]

Also unexplained at the moment, is the confirmed existence of some type of dark matter whose precise nature remains not known to us. It seems clear that neutrinos do not constitute its main component at all, so there are founded suspicions that the ultimate explanation could be based on the existence of fundamental particles of nature still unknown. All this hints point to the existence of particle physics beyond the Standard Model, or even to possible modifications of the gravitational interaction at large scales.

We also know that Einstein's theory of gravity, taken at face value, is inconsistent with quantum mechanics: a new paradigm is needed to formulate a quantum theory of gravity that allows us to understand the structure of spacetime at its most fundamental level. The most fruitful approach in this search has resulted from combining ideas from String Theory — a naturally quantized theory of gravity — together with tantalizing glimpses from the study of quantum black holes. The "holographic principle" has emerged as a powerful, though not yet fully understood, framework to overcome the limitations of conventional quantum field theory approaches to gravity. In a surprising turn of events, it has also given us a radical reformulation of some of the most difficult quantum field systems (such as quark gluon plasmas) in terms of the "dual" physics of black holes in higher-dimensional spacetimes.

##### ICCUB Contribution

ICCUB researchers carry out research in the areas of gravity, particle physics and the gauge/gravity correspondence. In the area of gravity, research is focused on the study of black holes in string theory and in higher-dimensional spacetimes, inflationary models and quantum gravity in de Sitter spaces. Finally, the gauge/gravity correspondence is applied to the study of the quark-gluon plasma and the computation of observables in gauge theories.

##### Lines of Research

- Dark matter and dark energy in cosmology and in particle physics
- Quantum and semiclassical gravity
- Black holes and gravity: New perspectives from strings and higher dimensions

##### Members