The second part, Nothing, explores science at the very limits of human perception, where we now understand the deepest mysteries of the universe lie. Professor Jim Al-Khalili sets out to answer one very simple question - what is nothing? His journey ends with perhaps the most profound insight about reality that humanity has ever made. Everything came from nothing. The quantum world of the super small shaped the vast universe we inhabit today, and Jim can prove it.

Professor Brian Cox visits Geneva to take a look around Cern's Large Hadron Collider before this vast, 27km long machine is sealed-off and the experiment to create the simulation of a black hole begins. When it's up and running, it will be capable of creating the conditions that existed just a billionth of a second after the Big Bang. Brian joins the scientists who hope that the LHC will change our understanding of the early universe and solve some of its mysteries.

Professor Jim Al-Khalili continues his investigation of the atom by looking at radioactivity, the Atom Bomb and the Big Bang, and even why we are here and how we were made. He shows that, in the quest to understand the atom, the mystery of how the entire universe was created became revealed

For centuries, the precise workings of gravity have confounded the greatest scientific minds - from Newton to Faraday and Einstein - and the idea of controlling gravity has been seen as little more than a fanciful dream. Yet in the mid 1990s, UK defence manufacturer BAE Systems began a ground-breaking project code-named Greenglow. 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 into the past and projecting into the future, Horizon explores science's long-standing obsession with the idea of gravity control. It looks at recent breakthroughs in the search for loopholes in conventional physics and examines how the groundwork carried out by Project Greenglow has helped change our understanding of the universe. Gravity control may sound like science fiction, but the research that began with Project Greenglow is very much ongoing, and the dream of flying cars and journeys to the stars no longer seems quite so distant.

Shocking new evidence has convinced some of the world's greatest physicists that the universe is a hologram. Using cutting-edge technology, they investigate the secrets of black holes and space-time to build the case for this game-changing discovery.
The holographic principle is a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string-theory interpretation by Leonard Susskind.
The holographic principle was inspired by black hole thermodynamics, which conjectures that the maximal entropy in any region scales with the radius squared, and not cubed as might be expected. In the case of a black hole, the insight was that the informational content of all the objects that have fallen into the hole might be entirely contained in surface fluctuations of the event horizon.

In the last in the series Professor Jim Al-Khalili explores how studying the atom forced us to rethink the nature of reality itself. He discovers that there might be parallel universes in which different versions of us exist, finds out that empty space isn't empty at all, and investigates the differences in our perception of the world in the universe and the reality.