Betti Hartmann (University College London, UK)

General Relativity is fundamentally deterministic, but this breaks down at space-time singularities. The weak cosmic censorship conjecture proposes that such singularities are always hidden inside black holes behind event horizons, preventing their observation. Still, their existence challenges determinism, motivating research into black hole mimickers—objects that resemble black holes but lack singularities or horizons. In this talk, I will discuss such black hole mimickers that arise in gravitating scalar field models. This includes boson stars, which are essentially self-gravitating macroscopic Bose-Einstein condensates, as well as frozen states of compact objects, for which the event horizon is replaced with a finite-thickness boundary connecting a nonsingular interior to a black hole-like exterior.