For the last 200 years, we have been fascinated with the idea of controlling gravity. But in the mid-1990s British aerospace manufacturer BAE Systems began a ground-breaking project code-named "Greenglow" which set about turning what many regarded as science fiction into reality. On the other side of the Atlantic, NASA was simultaneously running its own Breakthrough Propulsion Physics Project. It was concerned with potential space applications of new physics, including concepts like "faster than light travel" and "warp drives." Looking at these past projects and into the future, this BBC Horizon program explores science's obsession with the idea of gravity control. Are flying cars and journeys to the stars still the stuff of dreams?