The Many Incarnations of Dark Energy

I will discuss dark energy in a broad sense. I will begin with a general-level overview of the issues surrounding the accelerating universe, and will describe the theoretical challenges to constructing a viable explanation for the data. I will take the approach of effective field theory, and will describe how we think about new cosmological degrees of freedom in this context, and how knowledge from field theory should inform our thinking about cosmological models in general.

In the final part of the talk, I will focus on the topic of early dark energy in the context of the above discussion. I will describe some recent work trying to understand how we might address the fine-tuning problems of some attempts to address the Hubble tension.