What is the fourth dimension?

Answer 1

The fourth dimension is considered time.

We live in a three dimensional universe, where there is length, width, and depth. However, we can only exist at one point in time at any given moment. In the three dimensional world only our present self can exist. Hypothetically, in the fourth dimension, we can exist at all points in time, so our past, present, and future selves exist simultaneously.

Geometry

But in some forms of mathematics and spatial analysis, it is possible to have an object or location within more than three dimensions, the additional dimensions existing (as does time) outside of the normal 3-dimensional space. The term "n-space" applies to any space having more than 3 dimensions.

For a finite universe represented by a cube, a fourth dimension would be measured as the position of the cube along a line in any direction. Likewise, the fifth and sixth dimensions could be represented as locations or lengths along the perpendicular to the line and the perpendicular to the plane, respectively.

A 4-dimensional shape based on the 3-dimensional cube is called a tesseract. The shape in further dimensions is called a hypercube.

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