Buoyancy

S1 E6: Putting his faith in the science of buoyancy, Todd Sampson ties himself to a giant cluster of helium balloons in an attempt to defy gravity. With the help of astrophysicist Dr Lisa Harvey-Smith, Todd takes flight with 130 balloons to demonstrate the upward force of buoyancy. But this giant airship relies on calm conditions, and high winds threaten to derail the experiment.