In physics, spacetime is any mathematical moel that combines space and time into a single construct called the spacetime continuum. Spacetime is usually interpreted with space being three-dimensional and time playing the role of the fourth dimension. According to Euclidean space perception, the universe has three dimensions of space, and one dimension of time. By combining space and time into a single manifold, physicists have significantly simplified a large amount of physical theories, as well as described in a more uniform way the workings of the universe at both the supergalactic and subatomic levels.