Title: Understanding Dark Energy
The nature of dark energy is one of the most pressing problems confronting particle physics. What is the dark energy and how can we experimentally probe it? It is usually assumed that the dark energy is simply a cosmological constant. But, the observed value of the dark energy requires an extra-ordinary fine tuning that defies a natural explanation. In this talk, I will discuss new theoretical approaches to solve this problem and point to experimental opportunities that can be pursued to test these solutions. The theoretical ideas involve independently motivated phenomena such as bouncing universes and I will present controlled solutions within general relativity that accomplish these goals. Some of the experimental methods can be immediately pursued in CMB polarization and Lorentz violation experiments, while others can be implemented in emerging techniques such as proton storage rings. A third class of measurements require new sensors that operate in the THz regime.