Sagan reflects on the future of humanity and the question of 'who speaks for Earth?' when meeting extraterrestrials. He discusses the very different meetings of the Tlingit people and explorer Jean-François de La Perouse with the destruction of the Aztecs by Spanish conquistadors, the looming threat of nuclear warfare, and the threats shown by destruction of the Library of Alexandria and the murder of Hypatia. The episode ends with an overview of the beginning of the universe, the evolution of life, and the accomplishments of humanity and makes a plea to mankind to cherish life and continue its journey in the cosmos. The Cosmos Update notes the preliminary reconnaissance of planets with spacecraft, the fall of the Berlin Wall and the end of apartheid in South Africa, and measures towards the reduction of nuclear weapons.

This series deals with two of the deepest questions there are - what is everything, and what is nothing? In two epic, surreal and mind-expanding films, Professor Jim Al-Khalili searches for an answer to these questions as he explores the true size and shape of the universe and delves into the amazing science behind apparent nothingness.
he first part, Everything, sees Professor Al-Khalili set out to discover what the universe might actually look like. The journey takes him from the distant past to the boundaries of the known universe. Along the way he charts the remarkable stories of the men and women who discovered the truth about the cosmos and investigates how our understanding of space has been shaped by both mathematics and astronomy.