How Many Dimensions Can You See?

Flatland and how many dimensions you can see (HINT: it's not 3!)

Hi! I'm Jade. I make physics videos that will make you smarter while making you smile :)

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Do we see the world in 2D or 3D? Seems obvious doesn't it? Not so fast. To begin to understand we need to take a trip to a lower dimensional land.

Lineland is a one dimensional world where only lines exist. There is only left and right. Up, down, back and forth do not exist. Now what would an interaction between two citizens of line land look like? To each other, one dimensional lines LOOK like zero dimensional points. This is because, from their perspective, they can only see the front of each other. Even if they had see-through vision it would just look like a series of overlapping points. So in a 1 dimensional world, the citizens see in zero dimensions. Now let's move up one dimension.

Flatland is a two dimensional world which is perfectly flat. There is left, right, back, and forth, but no up and down. If we take a look at an interaction between some citizens of flatland, we see that to each other they all look like lines. So in a two dimensional world, the citizens see in one dimension.

So in a 1D world, they have 0D vision, in a 2D world, they have 1D vision. Can you spot the pattern? nD world means (n-1)D vision. It then follows that we (3D citizens) see in 2D. If you imagine yourself in our 3D world staring at a cube, notice you will only see a 2D square, the face of the cube. You can see length and width, but not depth. So why do you get the "feeling" that you can see depth?

Your brain has developed a plethora of techniques and "tricks" to help you perceive this 2D image as 3D. Watch the video to find out more!