This article is about space — the scientific and philosophical concept. For other uses of space, see space (disambiguation).

Space has a range of definitions.

  • One view of space is that it is part of the fundamental structure of the universe, a set of dimensions in which objects are separated and located, have size and shape, and through which they can move.
  • A contrasting view is that space is part of a fundamental abstract mathematical conceptual framework (together with time and number) within which we compare and quantify the distance between objects, their sizes, their shapes, and their speeds. In this view space does not refer to any kind of entity that is a "container" that objects "move through".

These opposing views are relevant also to definitions of time. Space is typically described as having three dimensions, and that three numbers are needed to specify the size of any object and/or its location with respect to another location. Modern physics does not treat space and time as independent dimensions, but treats both as features of spacetime – a conception that challenges intuitive notions of distance and time.


Space in physics

The definition of space in physics is contentious. Various concepts used to try to define space have included:

  • The structure defined by the set of spatial relationships between objects
  • A manifold defined by a coordinate system where an object can be located
  • That which separates objects from one another
  • The condition within the conceptual field of existence that provides the 'ground' for any manifested form and, as such, enables movement and all physical dynamics

In classical physics, space is a three-dimensional Euclidean space where any position can be described using three coordinates. Relativistic physics examines spacetime rather than space; spacetime is modeled as a four-dimensional manifold.

Before Einstein's work on relativistic physics, time and space were seen as separate dimensions. Einstein's work unified the two into spacetime. In spacetime, measurements of space and time are held to be relative to velocity.

Astronomy and space

In astronomy, space refers collectively to the relatively empty parts of the universe. Any area outside the atmospheres of any celestial body can be considered 'space'. In particular, the boundary between space and Earth's atmosphere is conventionally set at the Karman line. See outer space.

Mathematics and space

In mathematics, a space is a set, with some particular properties and usually some additional structure. Often a space is a vector space or a specific variety thereof. Kinds of spaces include:


Main article: Measurement

The measurement of physical space has long been important. Geometry, the name given to the branch of mathematics which measures spatial relations, was popularised by the [ancient Greeks]], although earlier societies had developed measuring systems. The International System of Units, (SI), is now the most common system of units used in the measuring of space, and is almost universally used within science.

Geography is the branch of science concerned with identifying and describing the Earth, utilising spatial awareness to try and understand why things exist in specific locations. Cartography is the mapping of spaces to allow better navigation, for visualisation purposes and to act as a locational device. Astronomy is the science involved with the observation, explanation and measuring of objects in outer space.

The philosophy of space

An issue of philosophical debate is whether space is an ontological entity itself, or simply a conceptual framework we need to think (and talk) about the world. Another way to frame this is to ask, "Can space itself be measured, or is space part of the measurement system?" The same debate applies also to time, and an important formulation in both areas was given by Immanuel Kant.

Immanuel Kant, in the Critique of Pure Reason, described space as an a priori notion that allows us (together with other a priori notions such as time) to comprehend sense experience. With Kant, neither space nor time are conceived as substances, but rather both are elements of a systematic framework we use to structure our experience. Spatial measurements are used to quantify how far apart objects are, and temporal measurements are used to quantify how far apart events occur.

Similar philosophical questions concerning space include: Is space absolute or purely relational? Does space have one correct geometry, or is the geometry of space just a convention? Historical positions in these debates have been taken by Isaac Newton (space is absolute), Gottfried Leibniz (space is relational), and [[Henri Poincar靝 (spatial geometry is a convention). Two important thought-experiments connected with these questions are: Newton's bucket argument and Poincar駳 sphere-world.

The psychology of space

The way in which space is perceived is an area which psychologists first began to study in the middle of the 19th century, and it is now thought by those concerned with such studies to be a distinct branch within psychology. Psychologists analysing the perception of space are concerned with how recognition of an objects physical appearance or its interactions are perceived.

Other, more specialised topics studied include amodal perception and object permanence. The perception of surroundings is important due to its neccesary relevance to survival, especially with regards to hunting and self preservation. "Veridical perception" is the term used to describe the processing of the information provided by the sensorary organs to an extent whereby it allows interaction with the actuality of that perceived.

It is worth noting that the way we perceive space may not neccessarily be representative of the actuality of space.

Anxiety and space

Space can also cause anxiety in people, with agoraphobia manifesting itself in some people as a fear of open spaces, and claustrophobia being the fear of enclosed spaces. Astrophobia is the fear of celestial space, Kenophobia is the fear of empty spaces and spacephobia is the fear of outer space.

Use of space

The definition of physical space in relation to ownership, in which space is seen as property, has long been an important issue. Whilst some cultures assert the rights of the individual in terms of ownership, other cultures will identify with a communal approach to land ownership. Spatial planning is a method of regulating the use of space at land-level, with decisions made at regional, national and international levels. Space can also impact on human and cultural behaviour, being an important factor in architecture, where it will impact on the design of buildings and structures, and on farming.

Ownership of space is not restricted to land. Ownership of Airspace and of waters is decided internationally.

Public space is a term used to define areas of land which are open to all, whilst personal space is the term used to define the amount of space a person likes to maintain between their own person and that of other people.


"Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." - Douglas Adams, The Hitchhiker's Guide to the Galaxy

"Interestingly, according to modern astronomers, space is finite. This is a very comforting thought-- particularly for people who can never remember where they have left things." - Woody Allen

"Beyond a critical point within a finite space, freedom diminishes as numbers increase. ...The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who do survive." - Frank Herbert, Dune

"Space is to place as eternity is to time." - Joseph Joubert

"Einstein's space is no closer to reality than Van Gogh's sky. The glory of science is not in a truth more absolute than the truth of Bach or Tolstoy, but in the act of creation itself. The scientist's discoveries impose his own order on chaos, as the composer or painter imposes his; an order that always refers to limited aspects of reality, and is based on the observer's frame of reference, which differs from period to period as a Rembrant nude differs from a nude by Manet." - Arthur Koestler, The Act of Creation

"Space, like time, engenders forgetfulness; but it does so by setting us bodily free from our surroundings and giving us back our primitive, unattached state" - Thomas Mann

"No creature loves an empty space;
Their bodies measure out their place" - Andrew Marvell, Upon Appleton House, to My Lord Fairfax

"When we contemplate the whole globe as one great dewdrop, striped and dotted with continents and islands, flying through space with other stars all singing and shining together as one, the whole universe appears as an infinite storm of beauty." - John Muir, Travels in Alaska

"Space - the final frontier." - Gene Roddenberry, Star Trek

"I have sat by night beside a cold lake
And touched things smoother than moonlight on still water,
But the moon on this cloud sea is not human,
And here is no shore, no intimacy,
Only the start of space, the road to suns." - F.R. Scott, Trans Canada

"Space is the breath of art." - Frank Lloyd Wright

See also



space perception ( Encyclop椩a Britannica from Encyclop椩a Britannica Online. Accessed June 12, 2005.


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