Space is the boundless three-dimensional extent in which objects and events have relative position and direction.Physical space is often conceived in three linear dimensions , although modern physicists usually consider it, with time , to be part of a boundless four-dimensional continuum known as spacetime . 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 . Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the Timaeus of Plato , or Socrates in his reflections on what the Greeks called khôra (i.e. "space"), or in the Physics of Aristotle ...