Everybody talks about space-time, string theory, parallel universe these days. When they talk about these topics, the concept of higher dimensions automatically pops out. Some people point out that time is the 4th dimension in space-time model (theory of General Gravity by Einstein). Others mention that there are more than 10 dimensions (very small to be noticed) in string theory, see image below for illustration purpose.
Our brain limitations
Let’s dig deeper into the concepts. We are born and live in 3D world. Our brain and eyes are wired to see only till 3 dimensions – length, width, and height, we can’t imagine the world beyond. And that, according to many researchers, is the reason we can’t see the fourth dimension, or any other dimension beyond that. Physicists work under the assumption that there are at least 10 dimensions, but the majority of us will never “see” them. Because we only know life in 3-D, our brains don’t understand how to look for anything more. It is similar to a 2D living being which can’t comprehend the 3D world.
2d world and 3d world – perception and change
Edwin A. Abbot published a satirical novel called Flatland: A Romance of Many Dimensions. He describes 2-dimensional objects life – a square with circles, triangles and rectangles. All the square sees only lines and to make sense of the shape they have to encircle the other objects, still difficult. When a 3d sphere enters his locked room in the 2-D world, he just can’t comprehend how something can suddenly appear from nowhere. At the same time, it is changing shapes as it is crossing the 2d plane. Then sphere takes the square to the 3d world after some time and square realise the source of confusion, he was limited by his wired brain and 2d world.
Curiosity – thinking complex
Now the square is very happy to see all the objects from the top, seeing their shapes easily including height. He asks the sphere, can you take me to more higher dimensions, I want to see more for which sphere doesn’t have any answer. The sphere is confused and lost. He also needs somebody from the higher dimension to show us how our world looks from the 4th dimension, without which we are hold up by our brain limitations. Similar is the case with us, the humans.
Every dimension is perpendicular to the previous dimensions, like 3rd dimension of the 3d world is perpendicular to the plane, for us it is very difficult to imagine the 90-degree angle to the 3d, again due to our limits :(. We are referring to the 4th or higher dimensions as spatial not time (space-time will be covered in a separate video).
Check the video for the demonstration of the concepts discussed in this blog and also follow the following resource for more rich experience to develop your understanding from different perspectives.
 Rotation of teserract projection – http://www.youtube.com/watch?v=BVo2igbFSPE
 Hands-on demo – http://www.youtube.com/watch?v=xWRAEfhQ3gw
 Flexible tesseract – http://www.youtube.com/watch?v=YL-vlONT2QM
 Carl Sagan explaining tesseract – http://www.youtube.com/watch?v=N0WjV6MmCyM
 Detailed discussions – http://www.math.union.edu/~dpvc/math/4D/models/welcome.html
 4D intuition in Virtual Reality – http://link.springer.com/article/10.3758%2FPBR.16.5.818
 String theory and extra dimensions – http://press.cern/backgrounders/extra-dimensions
 Research on complex shapes and dimensions – http://www.cs.indiana.edu/~hanson/