Through the Wormhole Season 2 Episode 4

To scientists it looks like the weakness of gravity, the existence of dark matter and the big bang may all be dependent on how many dimensions there are to the universe. But are the three dimensions we're used to too few or too many? This program examines the pet theories of several scientists about the dimensionality of our universe, how they are going about proving their theories and why their theories don't agree with the three dimensions that seem obvious to us.