Isn't the Fourth Dimension Time?
"Well wait a minute, incredibly handsome and knowledgeable library employee," you may exclaim, "isn't the fourth dimension TIME?"
You're so clever, aren't you?! Yes, time is sometimes considered to be a fourth dimension. But what we're going to talk about here is four SPATIAL dimensions. I hope you are prepared.
Tesseract, AKA Hypercube
So a square is two-dimensional, and a cube is three-dimensional. But when you go into the next dimension, a cube becomes something called a tesseract, also known as a hypercube, which shows up in all kinds of places such as A Wrinkle in Time and the movie S.Darko.
I don't even know how to describe a hypercube to you. Here's an animated gif of one rotating:
But what would be the point of an extra spatial dimension? We can barely walk around in our own 3D world without tripping over curbs and running into doorjambs! And this is answered by watching Cube 2: Hypercube which is the sequel to that one Cube movie I talked about earlier. It's about a group of people who, again, wake up in a locked room and have to figure out how to get out before they die, but it turns out that the cube they are trapped in this time is a hypercube.
Explore for Yourself
Probably the best way to explore the fourth dimension, though, is to play this 4D maze game that I found on the interwebs. It requires you to blur your vision and cross your eyes in order to even view it properly, but it promises to be an interesting expedition, if you dare to undertake it!
Photo credit: Wikimedia Commons
Josh Pearce is a closed, compact, convex figure whose 1-skeleton consists of groups of opposite parallel line segments aligned in each of the space's dimensions, perpendicular to each other and of the same length.