# What is sphere?

• (noun): A three-dimensional closed surface such that every point on the surface is equidistant from the center.

## Sphere

A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle, which is in two dimensions, a sphere is the set of points which are all the same distance r from a given point in space. This distance r is known as the "radius" of the sphere, and the given point is known as the center of the sphere. The maximum straight distance through the sphere is known as the "diameter". It passes through the center and is thus twice the radius.

### Some articles on sphere:

Kline Sphere Characterization
... In mathematics, a Kline sphere characterization, named after John Robert Kline, is a topological characterization of a two-dimensional sphere in terms of what sort of subset separates it ... A simple closed curve in a two-dimensional sphere (for instance, its equator) separates the sphere into two pieces upon removal ... If one removes a pair of points from a sphere, however, the remainder is connected ...
Marcus Theory - Outer Sphere Electron Transfer
... ligands in complexes, are tightly bound and constitute the "inner sphere" ... Reactions in which these participate are called inner sphere redox reactions ... The free solvent molecules constitute the "outer sphere" ...
Geotrekking - Navigation Equations - Trilateration
... Satellite position and pseudorange determines a sphere centered on the satellite with radius equal to the pseudorange ... is used to estimate receiver position based on the intersection of three sphere surfaces so determined ... case of two intersections of three sphere surfaces, the point nearest the surface of the sphere corresponding to the fourth satellite is chosen ...
1 33 Honeycomb - Kissing Number
... Each vertex of this polytope corresponds to the center of a 6-sphere in a moderately dense sphere packing, in which each sphere is tangent to 70 others the best known ...
Cubes in Relation To Spheres
... For every sphere there are multiple cuboids that may be inscribed within the sphere ... The largest cuboid which can be inscribed within a sphere is a cube ...

### More definitions of "sphere":

• (noun): A particular environment or walk of life.
Example: "His social sphere is limited"
Synonyms: domain, area, orbit, field, arena
• (noun): A solid figure bounded by a spherical surface (including the space it encloses).
• (noun): A particular aspect of life or activity.
Synonyms: sector
• (noun): Any spherically shaped artifact.
• (noun): The geographical area in which one nation is very influential.
Synonyms: sphere of influence

### Famous quotes containing the word sphere:

It is in the nature of allegory, as opposed to symbolism, to beg the question of absolute reality. The allegorist avails himself of a formal correspondence between “ideas” and “things,” both of which he assumes as given; he need not inquire whether either sphere is “real” or whether, in the final analysis, reality consists in their interaction.
Charles, Jr. Feidelson, U.S. educator, critic. Symbolism and American Literature, ch. 1, University of Chicago Press (1953)

I count him a great man who inhabits a higher sphere of thought, into which other men rise with labor and difficulty; he has but to open his eyes to see things in a true light, and in large relations; whilst they must make painful corrections, and keep a vigilant eye on many sources of error.
Ralph Waldo Emerson (1803–1882)

One concept corrupts and confuses the others. I am not speaking of the Evil whose limited sphere is ethics; I am speaking of the infinite.
Jorge Luis Borges (1899–1986)