If I Only Had a Brane

To think about this idea, we use "branes." A brane is a two-dimensional representation of our 3D universe. This means that the brane looks two-dimensional, when in reality there is a third dimension that we are not showing in our picture. Because of this 2D analogy, these parallel universes are called "branes," short for membranes.

Now, what happens if we take this brane and stick it in another dimension? We can stack branes one on top of the other in this hidden dimension like you would stack flat pieces of paper on top of each other. The key here is that in our three-dimensional universe, we would be totally unaware of this other dimension and hence the other universes around us.