Question: There is a large difference between a parallel universe and a parallel dimension , which is a common mistake as made by the media. If a parallel dimension were to exist , what do you think it could be?

Andres Olivares del Campo answered on 15 Nov 2016:

Hi!

Exactly, sometimes these two ideas get mixed up.

The concept of parallel universes follow the idea of a universe just like ours but in a different realm. Where parallel universes could be depends on the theory, but this is a very speculative field and we can’t really design experiments to test these theories!

Now, parallel dimensions (or extra dimensions) are a necessary condition for some theories that try to unify the four fundamental forces. String theory is a very popular one. In this theory, our universe is composed of up to 11 dimensions (7 more of what we understand now!)! If these dimensions exist, the idea is that they are so small that we cannot observe them. This is similar to the idea that, if you look at an orange from far away, you see its surface as flat. However, as you get close to it, you identify the wrinkles on it! Similarly, we could live in more than 3 spatial dimensions, but not able to notice them because they are very tiny.

I think the problem is also that our brain, is not prepared to understand these dimensions. We can understand depth, height and width. We can also understand time, but something beyond this is so difficult to grasp!