Space commonly refers to any region of the universe that contains a very low density of dust and gas particles, such as interstellar space. Space is also defined as the three-dimensional extent of the physical universe. In relativistic terms however, the volume of the universe is associated with a fourth dimension, i.e. that of time, thus defining a four-dimensional space-time.

Classical representations of space are based on Euclidean geometry, which describes objects in three-dimensional space using the Cartesian coordinate system and following a series of postulates and axioms. The Euclidean model of space is built from systems of parallel lines and objects in space are described as points using equations defining variables representing distances from real or imaginary parallel lines. The Pythagorean theorem provides an illustration of Euclidean space by providing a means to calculate the distance between any two points or objects. Some of the Euclidean...