OpenAI claims yes: their AI agents produced a proof (formalized in Lean) that the Navier-Stokes equations for 3D fluids can form a singularity in finite time.
Like you're 5: Imagine stirring soup. The math that tracks the swirls is Navier-Stokes. The big unsolved question was whether the swirls can ever get so tight and fast that the numbers explode to infinity and the math breaks. They say they found a special vortex where that happens.