Science and maths educator Selwyn Holland shares a lesson on physicist Albert Einstein and how his theories of relativity significantly changed our understanding of time and gravity with related findings about the speed of light and the concept of spacetime. You'll hear about Einstein's Theory of Special Relativity (and with it non-inertial motion, constant speed and time dilation) and his Theory of General Relativity (and with it gravity, acceleration and the curvature of spacetime) and how his famous equation E=mc2 fits in this story. Selwyn is also enthusiastic about Einstein the person and his humanitarian efforts and influence in the scientific community. This episode covers some of the historical context of his work, his contributions to debate about quantum mechanics and atomic theory, and his prediction of gravitational waves which was only recently confirmed.