At the largest scales, two ingredients dictate the distribution of matter in the Universe. The first is dark matter, acting as an invisible scaffolding held together by gravitational forces. The... Show moreAt the largest scales, two ingredients dictate the distribution of matter in the Universe. The first is dark matter, acting as an invisible scaffolding held together by gravitational forces. The second is dark energy, an enigmatic component responsible for the accelerated expansion of the Universe. Under these two forces, matter in the Universe organizes itself in the so-called cosmic web. The nodes of this network are large dark matter haloes, and this thesis explores how their boundaries provide information about the nature of dark energy and cosmology. Chapters 3 and 4 present robust theoretical predictions for this titular edge and discuss its simple physical interpretation. Chapters 2 and 5 corroborate these results by presenting measurements of this feature in weak-lensing data. The last scientific chapter of this thesis is a collection of studies in gravitational-wave physics. This chapter explores how these spacetime ripples observed from across the cosmos can be used to detect alternative theories of gravity. Show less
