| Our best-fitting theory of the universe for over 20 years is that the structure we see around us formed due to the gravitational interactions of visible matter with cold dark matter, and that the expansion of the universe as a whole is governed by a mysterious space filling fluid called dark energy. Together, cold dark matter and dark energy are thought to constitute over 95% of the universe's constituents. As we have entered the era of data-driven, precision cosmology, cracks in this paradigm have begun to emerge. Tensions between different cosmological data sets have worsened, dark matter has yet to be detected, and we are still no closer to understanding the underlying nature of dark energy. This has led theorists to speculate on alternative scenarios, such as dark matter having very weak interactions with visible matter, or that dark energy is due to a breakdown of the laws of gravity on cosmological scales. These alternative scenarios open up the possibility of testing cosmology using astrophysical objects since dark matter could be produced inside stars, and changing the laws of gravity changes how stars work. In this talk, I will tell you about this exciting program of testing cosmology using astrophysical objects by showing how they can help to answer two important questions: can dark matter destroy stars? and is gravitation universal? |