The inhabitants of flat-world are just trapped in the two dimension and when a 3-dimensional being wants to interact with that then it ‘s taken as a ghost or God. Just have a look on this..
Dimensions..the place where we live and execute. Here we can go right-left,backward-forward and up-down, which means we live and play in 3-dimensional world.
Now compare our world with the Flat-world. Now what you are thinking now?? What if there is 4th or more spatial dimensions (here i’m not talking about Time as 4th dimension )!!! What if some Extra-terrestrial Intelligence (Aliens) live in more that 3 dimension or they just know how to travel in those dimensions!!!
Or just simply what if any human knows how to travel on this dimensions!!! Then beware, your safe in your bank is not safe ,even though you implement the ultimate security of the all times. Beware, your thoughts, ideas and perception is no longer bounded.
Someone can just disappear from somewhere and just appear from no where!!!
Now turn to the technical point. We humans are one of the most intelligence creatures of the universe who wants to know everything around,even beyond their limited senses. Though we can see 4-D object, but we can see it’s projection in 3-D.
Suppose, a cube,
will appear as
in 2-D projections. So using this a inhabitant of flat-world can somewhat imagine that what is a cube in 3-D. Here you can see that 2-D perspective of 3-D object appears to be distorted. As we know for a cube all sides are equal and all angles are right angles, but in 2-D perspective,as shown in figure above, it appears the some sides are smaller and some angles are more than 90 degree and some are less than 90 degrees.
so,during mapping N dimension to N-1 or lesser dimension, some information gets lost.
Now here is the “tesseract” or a 4-D cube in rotation
Note that though it appears that some sides are smaller and some angles are not right angle, but if you had a 4-D eye to see this object in 4-D, then you’ll find that all sides of “tesseract” are equal and all angles are right angles. It’s similar to square and cube.
Now, what??? We want 4-D!!!!!! We want 5-D!!!!