## How Many Dimensions are there in the Universe according to different Theories

Here we will learn, how many dimensions are there in the universe according to different theories and why we find it impossible to perceive higher dimensions. Here you will know number of existing dimensions according to Classical Physics, Superstring Theory, M Theory and Bosonic String Theory.

## Dimensions according to Classical Physics

According to classical physics there are 3 dimensions of space and the fourth dimension is the time. Any object in the first dimension would have only one dimension i.e. length. If someone is living in a one dimensional Universe then he would be able to move in a straight line only. There would be no left and right or up and down for him. A straight line is an example of one dimensional object. While for two dimensional objects we have one more dimension added to it. So it would be a plain object having Length and breadth. A person living in a two dimensional universe can move freely in a plain only but cannot leave that plain. For him there would be no up or down. A square or a rectangle are examples of two dimensional objects. On adding one more dimension to a two dimensional universe, we enter into a three dimensional universe. Actually we live in a three dimensional universe where we can move in any direction in space. We can move in a straight line, take left or right turns or move in up or down directions as per our wish. Spheres, pyramids, cube and all the humans, animals are examples of three dimensional objects. So these were the first three dimensions of space according to classical physics. Actually we don't live in three dimensions of space only. We also live in a one more dimension known as time. In space we can move in any desired direction in all the 3 dimensions but in the fourth dimension time we can only move in the forward direction. Now we will discuss how many dimensions are there according to different theories.

## Dimensions according to Super String Theory, M Theory and Bosonic String Theory

Actually for mathematical consistency of string theory extra dimensions of spacetime are required. Superstring theory requires 10 spacetime dimensions while according to M theory there are total 11 dimensions. In Bosonic string theory spacetime is 26 dimensional. But now the question arises, if there are so many dimensions, why we are able to perceive only first 4 dimensions? Why we can not experience higher dimensions?

## Why We Can Not Perceive Higher Dimensions?

Actually according to some studies extra dimensions may be "curled up" at extremely small scales. The scale is too small to be visible to current experiments. It is very hard to imagine higher dimensions for our brain as we live in a 3 dimensional universe. Its similar to a case where for a person living in 2 dimensional space, it's very difficult to imagine a 3 dimensional world. This is the reason why we can not perceive higher dimensions.