Physics Colloquium

We briefly review the main ingredients of what constitutes our fundamental understanding of physical interactions. We then point out that, although this standard framework is very successful in explaining a wide range of phenomena, there is evidence, both empirical and conceptual, that it is not complete. One of the conceptual difficulties in the current picture is the enormous disparity between the strengths of gravitational and subatomic interactions, or the "hierarchy problem". This question may be resolved if new physical ingredients emerge, at microscopic distance scales that will soon be probed in particle physics experiments. As an intriguing example, we outline how a "warped" new dimension of space may address the hierarchy problem and shed light on other puzzling aspects of the standard description.