Relativity

Relativity, formulated by Albert Einstein, includes two fundamental ideas: Special Relativity and General Relativity. Special Relativity addresses physics in absence of gravity with two postulates: the laws of physics are the same for all observers, and the speed of light is constant for all observers. General Relativity, extends this to include gravity, viewing it as the curvature of spacetime around massive objects. This affects the path and speed of moving objects, creating what we experience as gravity. Summarily, relativity means that time, space and gravity can vary depending on your relative position and speed.