Professor Stephen Hawking mesmerised the world with his science best-seller A Brief History Of Time. Twenty years on he asks how much more do we know about the universe?

In this ground breaking and exciting documentary, Professor Stephen Hawking examines just how far our understanding of the universe has developed in our own lifetimes.

Taking on board the astonishing scientific advances of the past 20 years Hawking is able to introduce fresh ideas which even he dared not imagine two decades ago. In his own words: "Twenty years on, my need to find answers to the fundamental questions about our existence, is undiminished." Hawking drives this landmark series with his continued fascination with the big questions. How did the Universe begin? How will it end? What was there before it?

Hawking is our guide and mentor on a journey through the Universe, in which the world's most exciting and eminent scientists join him in explaining mysteries of physics in a unique and accessible way. From the macro to the micro Hawking explores supernovae, black holes, dark matter, and the sub-atomic world to bring the biggest questions of all to the small screen with extraordinary aplomb and clarity.