The adventures of the Time Lord have enthralled viewers for over 50 years, but they have also inspired generations to ponder what it would really be like to follow in the footsteps of the Doctor. Joined by celebrity guests, Professor Brian Cox draws on the latest theories as well as 200 years on scientific discoveries to tackle some of the big questions raised by the long-running show. Will it ever be possible to travel in time? Does extraterrestrial life exist in our galaxy? And how do you build something as fantastic as the Tardis?