We feel it every moment of our lives but for physicists, gravity is the longest running unsolved mystery of the universe. Why do all objects that have mass pull on one another? Cutting-edge theories are proposing unexpected answers: Gravity could be another force in disguise, a thermodynamic mirage, or even, a shadow of a hidden holographic universe. If so, the force that holds us to the surface of the earth, and holds the earth in orbit around the sun, may be a trick of the mind. We feel it, but it may not be real. Is Gravity an Illusion?

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.

How does light escape from the sun? We take a journey from the center of the sun, following the path of light. We witness its fiery birth from in the core, its 430,000 mile battle against gravity and magnetism, and its escape from the solar surface.

Head beyond the Asteroid Belt for an out of this world experience. Welcome to Jupiter, home of high adrenaline adventure. Plunge into its mysterious depths. When you drop through the clouds it would get darker and hotter. At the center the temperatures are hotter than the surface of the sun and the pressures are unimaginably high.

This documentary journeys with the scientists into the heart of a giant. Juno is the Nasa mission designed to peer through Jupiter's swirling clouds and reveal the wonders within. By projecting a 70-foot-wide, life-size Juno on a Houston rooftop, Scott Bolton, head of Juno, shows us how its fragile electronics are encased in 200kg of titanium. As Scott puts it, 'we had to build an armoured tank to go there.' Professor Andrew Ingersoll, Juno's space weatherman, reveals they have seen lightning inside Jupiter, perhaps a thousand times more powerful than Earth's lightning. This might be evidence for huge quantities of water inside Jupiter.
Under the extreme conditions of Jupiter thousands of miles under the surface, hydrogen becomes a liquid metal. Juno is finding out how much liquid metallic hydrogen is inside Jupiter, and scientists hope to better understand how this flowing metal produces the most powerful aurora in the Solar System. But what is at Jupiter's heart? In Nice, Prof Tristan Guillot explains how Juno uses gravity to map the planet's centre. This can take scientists back to the earliest days of the solar system, because Jupiter is the oldest planet and it should contain clues to its own creation. By chalking out an outline of the Jupiter, Tristan reveals there is a huge rocky core - perhaps ten times the mass of Earth.

A deep sea diver is stranded on the seabed with 5 minutes of oxygen and no hope of rescue. With access to amazing archive this is the story of one man's impossible fight for survival.
Chris Lemons were carrying out repairs 100m below the surface of the North Sea, supported by the vessel Bibby Topaz. The vessel's dynamic positioning system failed, causing it to snap the umbilical tether that provided Lemons oxygen, as well as hot water to heat his suit, power for his light, and a radio link to the surface. He was left with only the few minutes of breathable gas contained in the cylinders he wore on his back.
For reasons that are unclear, Lemons survived for around 30 minutes while he was located by a remote underwater vehicle and then by Yuasa, who was able to pull him back onboard the diving bell. The documentary uses genuine footage and audio recorded at the time of the accident on the divers' radios and body cameras, supplemented with interviews of several of the individuals involved, as well as some reconstructed footage, to tell the story of the accident.