What is the Fourth Dimension ?

You might have watched 4D movies, or put on 3D glasses, created 2D drawings, or found a 1D mark on your newly painted wall. So, what is it that really qualifies each of the four dimensions?

Some begin with the zeroth dimension, but we will begin by wrapping our minds around the first dimension. It consists of points. Points in space close together in a row can make lines.

Everything in the first dimension is a point or a line. Lines only vary by their length and orientation.

The second dimension exists in another direction perpendicular to the first. A line in the first dimension and a line on another identical dimension perpendicular to the first might intersect. Thus, we have formed the corner of a square in the second dimension. For a square in the second dimension to be represented as a cube, we must introduce the third dimension. The x-y plane of the second dimension becomes the x-y-z plane of the third.

Reach an arm out in from of you and turn your palm up towards the sky. This is dimension one. Turn your palm so that it is parallel to the walls. This is dimension two. Now turn your palm so that it is slanted and diagonally facing the ground. This is one way to visualize the three planes when beginning study of multivariable calculus. Scientists don’t even know if there is a fourth dimension. Einstein thought that one would include space and time. The fourth dimension might be space curled up unbelievably small all around us. Some picture it as another series of dimensions around the third. So our question is unanswerable right now- but that’s part of what makes physics so beautiful! 🪐