Stephen Hawking, the world's most famous living scientist explores the greatest mysteries of the cosmos. In three landmark instalments he reveals the wonders of the universe as never seen before. Definitive, provocative, surprising, and beautiful, Into the Universe with Stephen Hawking is a fascinating look through the mind's eye of one of the finest brains on the planet. In 'Aliens' Hawking considers one of the most important mysteries facing humankind - the possibility of alien, intelligent life. He leads us on a journey rendered in eye-popping detail, from the moons of Jupiter to a galaxy maybe not so far, far away. We will meet possible aliens and wonder at their form, we will delve into the very principles of what it is to call something alive, and we will calculate the likelihood of 'contact' being made.

The simple act of making an apple pie is extrapolated into the atoms and subatomic particles (electrons, protons, and neutrons) necessary. Many of the ingredients necessary are formed of chemical elements formed in the life and deaths of stars (such as our own Sun), resulting in massive red giants and supernovae or collapsing into white dwarfs, neutron stars, pulsars, and even black holes. These produce all sorts of phenomena, such as radioactivity, cosmic rays, and even the curving of spacetime by gravity. Cosmos Update mentions the supernova SN 1987A and neutrino astronomy.

We move around in space, but we are stuck in a prison of time moving ever forwards. Einstein said, 'The distinction between past, present and future is only a stubbornly persistent illusion.' Is our experience of the ticking clock merely a trick of the mind? Could science ever make the clock move backwards? Experiments in quantum physics are showing that the future influences the present: what happens later limits the choices we think we have now. The laws of physics say visiting or talking to ourselves in the past is possible – but changing history once we get there is not.

It is one of the most baffling questions that scientists can ask: how big is the Universe that we live in? Follow the cosmologists who are creating the most ambitious map in history - a map of everything in existence. And it is stranger than anyone had imagined - a Universe without end that stretches far beyond what the eye can ever see. And, if the latest research proves true, our Universe may just be the start of something even bigger. Much bigger.

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.

The film looks at the latest understanding of black holes, featuring an interview with Stephen Hawking. Black holes are one of the greatest mysteries in the universe. They behave in a way that is contrary to laws of physics and one has never actually been seen. However, the recent detection of gravitational waves, as predicted by Einstein, proves that black holes exist and provides a way to investigate their remarkable behaviour and properties.