Twenty-six thousand light-years from Earth, a single star named S2 has been silently writing the proof of one of physics' greatest theories — tracing an orbit around an invisible mass four million times heavier than our Sun. Over nearly three decades, two independent teams of astronomers watched this stellar messenger complete its circuit, measuring the subtle warping of spacetime that only Einstein's general relativity could explain. Their patience was rewarded with the 2020 Nobel Prize in Physics, and with the confirmation that at the heart of our galaxy sits a supermassive black hole — not