Time: 20. December 2019
Place: Institute of Physics
Title: The notion of modified gravity and its use in cosmology
We will analyze the notion of modified gravity, i.e. the ways in which GR can be changed, foremost in the IR regime relevant to cosmology. We will introduce several different definitions of the notion "modification of gravity", and discuss their differences. As it will turn out, the crucial role in different definitions plays the number of degrees of freedom in the theory. In the end, we will give a short overview of the Standard Model of cosmology (the so-called $\Lambda$CDM model, which was awarded this year with one half of a Nobel prize), in the context of the idea of modified gravity.