The world is built on different planes of existence. We call these planes "Dimensions" Only three of the dimensions, are known, seen, and understood by human beings. The 1st Dimension is a flat line that travels from one point to another. The 2nd Dimension is a plane made up intersecting 1st Dimensional Lines. And the 3rd Dimension is a polyhedron which is made up of intersecting planes. And that's all we know so far. Scientists have spent years trying to unlock the true, undeniable answer to what the 4th dimension is. Well, assuming that the pattern remains consistent, the 4th dimension would be made up of intersecting polyhedrons. To give a name to these hypothetical 4th dimensional shapes, I will call them "Quadriplanes". So one might think well the answer is simple, just draw two cubes on top of each other and connect them. In a way that's true, but it is also a matter of how you draw the two cubes. If you arrange them linearly it just makes a Rectangular Prism. That is the geometric/mathematical part of it.
   There is also the physical part of it. What is the fourth dimension like in reality? Does it have a definite shape? Does it sustain forms of life that we are unable to perceive? If a regular Strawberry was transformed into a 4-dimensional strawberry would it still be the same strawberry or would it taste better, or worse? Okay maybe that's going too far, but we the world could be described much more greatly if we had "4th Dimensional" words to describe things. But I digress.
   So my idea is what if the 4th Dimension is already within our reach, or at least the key to finding it? What if the 4th Dimension is Light itself, or something that is contained in the space around us? I think this, because look in mirror. When light hits a mirror, and perhaps even when it doesn't, an image of the physical objects is being sort of "projected" onto the mirror. If you look closely at a mirror. If you try to look further past the border frame where the mirror ends, It does not suddenly reverse and reflect what is on the opposite side instead. If there is a lamp to the right of the mirror, and you move left and look at the right edge of the mirror, you can see the reflection of the lamp, even though it is not even in front of the mirror. So the function of a mirror is dependent on the properties of light, and the way it bounces off of solid objects, with different textures, forms, etc. And when you are moving in front of a mirror, The reflection does not randomly stop, and only show what it can see. It changes perspective. But it does so in a very logical way. So the trick of the mirror is independent of our vision, and perceptions, but somehow it still has perspective. Even though it's a flat piece of glass with light shining on it. Okay, so what does this have to do with dimensions? Please allow me to continue.
   Many surfaces are rough and coarse and do not reflect any light at all. So you would never see a reflection in a solid brick wall. But does that mean there is no reflection? If you add a substance to the brick wall that allows it to reflect light, Suddenly you will see a reflection. Now I have a question for you? Does the reflection randomly appear when the substance is hit by the light? Or is the light already projecting an image, and the substance acts like a conductor and takes in the light, and then translates it into a reflection? Kind of like how the specific sound in a soundwave is the same and always will be the same until it hits someone's ear or dissipates. Just because you weren't around to hear a bird chirp, and suddenly you hear chirping when you stand in a specific place, that does not mean the sound was not a sound of chirping before you heard it. It just would not have anything to translate it into what we know as sound. So what if light is constantly project images of objects onto other objects even when we can't see it. This Idea can be strengthened by the presence of shadows. An object will still leave a shadow on a wall that cannot display a reflection. Does that mean the rest of the light bouncing off the object does not exist until a mirror is placed in front of it? Well I don't think so. I think that an image of the object is already being projected on the wall. So if light projects images of things on other things, and it is doing this infinitely to everything that is being lit up by the light, then there are images of that one object all over the room, and the shadows/reflections are only the most visible ones. Or even if the image only gets reflected in the direction of the flow of light waves, if you turn on another light and place it next to the object, it will create another image. As these images travel through space to hit the wall, they might intersect at some point. So imagine that the light images, the shadows, reflections, etc were extensions of the main object. Imagine you are drawing the object and you include all  of those aspects in the drawing, but as if they were one whole thing. The light adds an extra layer to the shapes. It is not part of the object, but still takes a shape that is uniform to the object, and even adds onto that shape. Imagine you are in a fun house at a carnival, and you find the room of mirrors. You find a circular area that is surrounded by mirrors and stand in the center of it. Now your reflection is in all of the mirrors. Also the mirrors are reflecting each other, so even more images of you have been produced. And the projections of light going in between all the mirrors flying across the empty space, are all intersecting and intertwining, and forming one big, invisible, mega-shape. The infinite images of you are all part of your fourth dimensional shape.
   I may have made errors here and there, but I think that I have  very strong case here, and I hope I can inspire some of you to ponder this too. Thanks for reading.

The 4th dimension would be impossible as far as I know. I think it stops at 3 (Unless it's used in movie terms)

Pokemonfan1000 : Well, i've heard from somewhere that only a few people on Earth can see 4D. I think it's nonsense, but i was watching a detailed video about the fourth dimension anyway. That's where i learned that from.

The 4th dimension is the media dimension.

TV, Video Games, Music, it's all right in front of you. Wake up sheeples

MarioLucarioFan64 : Ah ok. What was the documentary called.

I subscribe to the theory of four-dimensional space as described by Minkowski's spacetime continuum. We experience only snippets of the fourth dimension as time. We have memories of before and after but we don't have the actual ability to perceive more than a tiny snapshot of the fourth dimension. It's a continuum along where we travel that is measured by time. So, if you could actually see the fourth dimension, we would look like long snakes, starting as babies, worming around each other as 'time' passes, and ending with our deaths.

Math supports the existence of it and the theory behind it and the deductive reasoning is impressive. If you ever want to blow your mind, check out some of the Wikipedia articles about Four-dimensional space-time. It's mind blowing.

TheBWoods15 : tl;Dr. Plus, it looks like a wall of text - could you kindly add a few line breaks to break up the paragraphs, please?

Ghostbear1111 : I kinda agree with you, but the fourth dimension is in fact time. But there are other dimensions which are similar to what you're kinda suggesting, in my opinion.

There's three extended space, one extended time... And about six or so curled up dimensions, some which might be time, others which might be space, from what I've read.