Space is the boundless three-dimensional extent in which
objects exist and events occur and 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. In mathematics,
"spaces" are examined 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. 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 khora, or in the Physics of Aristotle in
the definition of topos, or even in the later "geometrical conception of
place" as "space qua extension" in the Discourse on Place of the
11th century Arab polymath Alhazen.
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. Other natural
philosophers, notably Gottfried Leibniz, thought instead that space was in fact
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.
