Dimensions are used to measure the amount of movement available in a given space. In common parlance, an object’s size and shape referred to its dimensions. In science fiction and New Age philosophy, a dimension can also refer to a different plane of existence.

For our purposes, our physical world appears to be a four dimensional world. Three of those dimensions are spatial – we can move up or down, forward or backward, right or left. We can also combine these movements, moving forward and to the right to move in a northeasterly direction.

The fourth dimension is time. Unlike the other three dimensions, where you can move in any direction, time seems to move in only one direction. However, scientists studying chaos theory and other high-level physics problems believe that time can be moved into directions. Unfortunately, we don’t know how this is done yet.

In mathematics, dimensions become a coordinate system. This has been put to practical use in the measures of latitude and longitude found on Earth. By adding a third measurement, altitude, the position of a three-dimensional object can be shown in three-dimensional space.

In science fiction, the word dimension is often used interchangeably with “parallel universes”, other planes of existence invisible to us from this plane. According to this theory, the other planes are very close by. However, this distance is measured in a higher spatial dimension, not the four dimensions used today.

2-dimensional renderings (i.e., flat drawings) of a 0-dimensional point, a 1-dimensional line segment, a 2-dimensional square, a 3-dimensional cube, and a 4-dimensional tesseract. Courtesy Wikipedia.