SPACE Space is a three-dimensional continuum containing positions and directions . [ 1 ] In classical physics , physical space is often conceived in three linear dimensions . Modern physicists usually consider it, with time , to be part of a boundless four-dimensional continuum known as spacetime . [ 2 ] The concept of space is considered to be of fundamental importance to an understanding of the physical universe . However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework . In the 19th and 20th centuries mathematicians began to examine geometries that are non-Euclidean , in which space is conceived as curved , rather than flat , as in the Euclidean space . According to Albert Einstein 's theory of general relativit...