Explore Einstein's lesser-known but most significant equation in this 54-minute lecture by Sean Carroll at The Royal Institution. Delve into the complexities of general relativity, understanding how spacetime curvature relates to mass and energy distribution. Learn about Newton's equations, the two types of relativity, and the importance of spacetime geometry. Discover the principle of equivalence, non-Euclidean geometry, and key concepts like the Metric Tensor and Riemann tensor. Examine how Einstein's equation forms a physical theory of gravity, its solutions, and practical applications in predicting phenomena and detecting black holes. Gain insights into the twisting of time and space as depicted in the film Interstellar, and unravel the mysteries of the universe through this comprehensive exploration of Einstein's groundbreaking work.