I remeber reading about this somewhere...(If I can I'll post a link)
What if the small strings of string theory, are whole universes on what is called a membrane? Millions of infinite universes that matter in our dimensions can't travel to because they based based on different and smaller dimensions, something we might call 10^-46D. And perhaps the scary part is, what if we are just a small string membrane in a much larger Dimensioned universe, next to trillions of parralel strings, which have equivalent dimensions to that of ours? The placnk (I don't think I spelled that right) length, is just how small we can get in our dimension. The strings below us, because even their 4th dimension is wraped in a way smaller then ours, a thousand universes may be destroyed in the blink of an eyelid. What do you think?

It is interesting, but nothing more can be said about it really, as it is only a theory and lacks proof. There are four dimensions: length, width, depth, and, to some, time. But personally, I do not think time should be a dimension because we only perceive our universe in 3 dimensions. I cannot fathom what it would be like to perceive something with more than three dimensions, excluding time. It seems impossible.

Yep, the extra spacial dimensions are Calabi-Yau manifolds. So far nothing but mathematical 'magic'. String Theory has no (using our current technology) testable/falsifiable predictions and some physicists, rightfully so, toss it in the 'religious' basket. String Theorists are currently riding on faith alone. It's a wonder they still get funding. Actually, with the new collider being built they're hoping that they start seeing some evidence to support their theory. Only time will tell.