Explore the cutting-edge research on black holes in this 53-minute lecture by Vitor Cardoso from the Niels Bohr Institute and Lisbon, IST, presented at the Galileo Galilei Institute. Delve into the new horizons of testing the black hole paradigm, examining singularities, cosmic censorship, and the uniqueness of black holes as perfect laboratories. Investigate fundamental questions surrounding black hole spectroscopy, including the validity of linear ringdown descriptions and one and two-mode estimates. Analyze nonlinearities in ringdown, spectral stability, and environmental effects. Conclude by exploring bouncing geometries and energy amplification in the context of young dying horizons. Gain insights into the latest developments in black hole research and their implications for our understanding of the universe.