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1. Space is the boundless, three-dimensional extent in which objects and events occur and have relative
position and direction.[1] Physical space is often conceived in three linear dimensions, although
modern physicists usually consider it, with time, to be part of the boundless four-dimensional
continuum known as spacetime. In mathematics one examines 'spaces' with different numbers of
dimensions and with different underlying structures. The concept of space is considered to be of
fundamental importance to an understanding of the physical universe although 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, in his reflections on what the Greeks called: chora /
Khora (i.e. 'space'), or in the Physics of Aristotle (Book IV, Delta) in the definition of topos (i.e. place),
or even in the later 'geometrical conception of place' as 'space qua extension' in the Discourse on Place
(Qawl fi al-makan) of the 11th century Arab polymath Ibn al-Haytham (Alhazen).[2] Many of these
classical philosophical questions were discussed in the Renaissance and then reformulated in the 17th
century, particularly during the early development of classical mechanics. In Isaac Newton's view,
space was absolute - in the sense that it existed permanently and independently of whether there were
any matter in the space.[3] Other natural philosophers, notably Gottfried Leibniz, thought instead that
space was a collection of relations between objects, given by their distance and direction from one
another. In the 18th century, the philosopher and theologian George Berkeley attempted to refute the
'visibility of spatial depth' in his Essay Towards a New Theory of Vision. Later, the metaphysician
Immanuel Kant said neither space nor time can be empirically perceived, they are elements of a
systematic framework that humans use to structure all experiences. Kant referred to 'space' in his
Critique of Pure Reason as being: a subjective 'pure a priori form of intuition', hence it is an
unavoidable contribution of our human faculties.
In the 19th and 20th centuries mathematicians began to examine non-Euclidean geometries, in which
space can be said to be curved, rather than flat. According to Albert Einstein's theory of general
relativity, space around gravitational fields deviates from Euclidean space.[4] Experimental tests of
general relativity have confirmed that non-Euclidean space provides a better model for the shape of
space.