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?

For one night only, Professor Brian Cox goes unplugged in a specially recorded programme from the lecture theatre of the Royal Institution of Great Britain. In his own inimitable style, Brian takes an audience of famous faces, scientists and members of the public on a journey through some of the most challenging concepts in physics. With the help of Jonathan Ross, Simon Pegg, Sarah Millican and James May, Brian shows how diamonds - the hardest material in nature - are made up of nothingness; how things can be in an infinite number of places at once; why everything we see or touch in the universe exists; and how a diamond in the heart of London is in communication with the largest diamond in the cosmos.

Time is woven into the fabric of the universe as one of the dimensions in which we live our daily lives. But maybe it is only a brain state that we use to piece together events. Could it exist only in our minds? Your sense of time can be totally different than the person next to you. This and other theories illustrate that time is an illusion and does not really exist. The world's top physicists tackle this fundamental question, does time exist, and offer new ways to perceive the physical world.

How did Hitler decide he was a messiah and persuade a whole nation to follow him to damnation? This is a subject that has been mined many times in fiction - Raiders Of The Lost Ark, Constantine, Hellboy, Bulletproof Monk and English horror writer James Herbert's book The Spear - as well as documentary. Based on Ken Anderson's 1995 book of the same name, this aims to show how the Nazi party was originally made up of several occult groups that believed a messiah was on the way to save Germany.

The sparkling blue waters of the Mediterranean Sea are home to over 700 varieties of fish and almost 10 per cent of the world's marine species. Its coastline is one of the most densely populated in the world and the human pressure on this sea is magnified each summer with the influx of holiday makers. Western civilisation developed around these shores but now human activity is having a profound effect on this endangered sea.

The final part reveals how our knowledge of cells has brought us to the brink of one of the most important moments in history. Scientists are close to repeating what has happened only once in four billion years - the creation of a new life form.