Speaker
Description
The structures of the Universe can affect the large-scale cosmic dynamics. This effect is known as cosmic backreaction. Although the effect has been known and studied for decades, it is still unclear how important the effect is in our Universe. One can attempt to quantify the effect in several different ways, but the resulting estimates vary wildly, depending on the introduced approximations. It is therefore unclear to what extent (if at all) backreaction is related to dark energy, cosmological tensions and how important it is in relation to testing theories of gravity beyond general relativity. In this talk, I will present the concept of cosmic backreaction and how it may be related to dark energy and cosmic tensions, as well as why it may be particularly important when studying gravity beyond general relativity. I will also review why backreaction is so difficult to quantify and discuss the necessary steps remaining before we can make truly trustworthy theoretical predictions of its importance in our universe. Lastly, I will discuss the possibility of quantifying backreaction through observations and how this fits into a larger strategy of studying observations model-independently.