Michio Kaku Explains String Theory: Multiverses - One Possibility As To Where Some UFO's Originate From?
This could be the answer.
Theoretical physicist Michio Kaku explains the basics of String Theory.
Our physical space is observed to have only three large dimensions and — taken together with duration as the fourth dimension — a physical theory must take this into account. However, nothing prevents a theory from including more than 4 dimensions.
In the case of string theory, consistency requires spacetime to have 10 (3+1+6) dimensions. The fact that we only see 3 dimensions of space can be explained by one of two mechanisms: either the extra dimensions are compactified on a very small scale, or else our world may live on a 3-dimensional submanifold corresponding to a brane, on which all known particles besides gravity would be restricted.
