# 4D

geometric space with four dimensions
(Redirected from Fourth dimension)

4D, meaning the 4 common dimensions, is an important idea in physics referring to three-dimensional space (3D), which adds the dimension of time to the other three dimensions of length, width, and depth. In geometry, the fourth dimension is related to the other three dimensions by imagining another direction through space; just as the dimension of depth can be added to a square to create a cube, the fourth dimension can be added to a cube to create a tesseract.

A tesseract moving along the 4D axis
A 4D torus rotating on the 4D axis.

In mathematics, four-dimension space is an abstract concept which has been studied by mathematics and philosophers for many years. Mathematicians who studied four-dimension space in the 19th century include Möbius, Schläfi, Bernhard Riemann, and Charles Howard Hinton.

In the 20th century, the idea of spacetime was developed by Albert Einstein, connecting space and time together. The difference is that spacetime is not a Euclidean space, but instead is called "Minkowski spacetime".