Everything about Two-dimensional totally explained
In mathematics the
dimension of a
space is roughly defined as the mimimum number of
coordinates needed to specify every
point within it. Dimensions can be thought of as the
axes in a
Cartesian coordinate system, which in a three-dimensional system run left-right, up-down and forward-backward. A set of three
co-ordinates on these axes, or any other three-dimensional coordinate system, specifies the position of a particular point in
space. In the physical world, according to the
theory of relativity the
fourth dimension is
time, which runs before-after. An event’s position in space and time is therefore specified if
four co-ordinates are given.
On
surfaces such as a
plane or the surface of a
sphere, a point can be specified using just two numbers and so this space is said to be two-dimensional. Similarly a
line is one-dimensional because only one co-ordinate is needed, whereas a point has no dimensions. In
mathematics, spaces with
more than three dimensions are used to describe other manifolds. In these
n-dimensional spaces a point is located by n co-ordinates (x
1, x
2, … x
n). Some theories, such as those used in
fractal geometry, make use of
non-integer and
negative dimensions.
Another meaning of the term "dimension" in physics relates to the
nature of a measurable quantity. In general, physical measurements that must be expressed in
units of measurement, and quantities obtained by such measurements are
dimensionful. An example of a dimension is
length, abbreviated L, which is the dimension for measurements expressed in units of length, be they
meters,
nautical miles, or
lightyears. Another example is
time, abbreviated T, whether the measurement is expressed in
seconds or in
hours. Speed, which is the distance (length) travelled in a certain amount of time, is a dimensionful quantity that has the dimension LT
−1 (meaning L/T). Acceleration, the change in speed per time unit, has dimension LT
−2.
Science fiction
Science fiction texts often mention the concept of dimension, when really referring to
parallel universes, alternate universes, or other
planes of existence. This usage is derived from the idea that in order to travel to parallel/alternate universes/planes of existence one must travel in a spatial direction/dimension besides the standard ones. In effect, the other universes/planes are just a small distance away from our own, but the distance is in a fourth (or higher) spatial dimension, not the standard ones.
One of the most heralded science fiction novellas regarding true geometric dimensionality, and often recommended as a starting point for those just starting to investigate such matters, is the 1884 novel
Flatland by Edwin A. Abbott. Isaac Asimov, in his foreword to the Signet Classics 1984 edition, described
Flatland as "The best introduction one can find into the manner of perceiving dimensions."
More dimensions
Further Information
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