Well, we know that at least 3 dimensions exist beause we can move about in them. General relativity says there are 4 by adding time to the 3 spatial dimensions we are famiiar with. String theory says 10, and supergravity has 11.
But what are they? In another thread someone gave 1 definition which is that a dimension is a value that enables us to fix an event in spacetime (a more mathematically based definition of a space is "the minimum number of coordinates needed to specify every point within it"). But that is just a mathematical construct, it doesn't really say what dimensions are.
I don't know the answer. When you consider that the compactified dimensions of some theories are so ridiculously small that nothing can exist inside them except gravity, it makes a definition even harder.
If dimensions do exist, then can we compare it to Kamui world with the real Earth? (This was just an example on how dimensions really do look like in Narutoverse)
I am talking about the universe and the Earth. I've heard many theories that dimensions really do exist, however the question is where and how?
A dimension is a human concept , made by humans to try to understand the world , it helps to make a description.
We made the link between the mathematicals vectorial spaces and our space , seing a direction as a dimension , we called time a dimension , we looked at the universe as a vectorial space of 4 dimensions with time as a "particular" dimension.
It has been applied to our world with great results , it looks like it works great , but it doesn't explain everything yet.
We assumed that Space was 3 directions , so 3 dimensions (x, y, z) , but many theories say that space is still growing , or have an end , we now know that space can be dilated or compressed...So it's not that easy.
It's not because that works great that it is truth , classical physics worked great for centuries and is still working great , but classical physics can't explain everything , so it must be wrong.
We put time as a particular dimension and that worked great until we saw that an object moving very fast made the time go slower for the object moving , that's why astronauts come back to Earth younger than if they stayed on Earth...
Our concept of 4 dimensions descripting everything in the world is false , but works great for a lot of things.
That's why "maths science-fictionists" are looking for a theory that will explain everything , like the string theory , who is going to find the best fan-fiction?
Adding theoricals dimensions is something that they really like to do nowadays to start to build their fan-fiction that will fit all the facts.
Kamuiland is another space linked to Narutoverse's space (if you move in Kamuiland you'll appear elsewhere in Narutoverse) and to Narutoverse's time (the same time acts on the 2 spaces).
Kishimoto can go in many directuions from that point.