The Accelerating Universe: Landscape or Modified Gravity?

          @misc{ pirsa_PIRSA:08020046,
            doi = {10.48660/08020046},
            url = {https://pirsa.org/08020046},
            author = {Dubovsky, Sergei},
            keywords = {Cosmology},
            language = {en},
            title = {The Accelerating Universe: Landscape or Modified Gravity?},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {feb},
            note = {PIRSA:08020046 see, \url{https://pirsa.org}}
          }
          

Abstract

The most remarkable recent discovery in fundamental physics is that the Universe is undergoing accelerated expansion. A proper understanding of its physical origin forces us to make a hard choice between dynamical and environmental scenarios. The former approach predicts the existence of a new long distance physics in the gravitational sector, while the second relies on the vast landscape of vacua with different values of the cosmological constant. I will discuss achievements and shortcomings of both approaches, and illustrate them in the concrete examples.