Gravity might seem like the simplest force in nature—just ask Newton’s falling apple. But when you look closer, gravity becomes one of the biggest puzzles in physics. Einstein’s theory of general relativity revolutionized our understanding by showing that mass curves spacetime itself. Yet even today, gravity refuses to fit neatly with quantum mechanics, the theory that governs the very small. This mismatch hints at the deep tension between relativity and quantum physics. We’ll start with the everyday experience of falling objects and expand into the strange and fascinating problems gravity poses across the universe. Why can’t we reconcile gravity with quantum theory? What’s happening with mysterious dark matter and dark energy, which seem to dominate the cosmos? And why are researchers testing gravity at incredibly small distances to search for hidden forces or extra dimensions? We’ll explore some of the most exciting modern experiments — ultra-sensitive interferometers with light or atoms; lunar distance measurement; and microdiamonds that are in two places at the same time — probing gravity in ways Einstein could only have dreamed of. Join me to discover why gravity, the oldest force we’ve studied, may also be the newest frontier in physics.