From unexplained flashes in the night sky to flying saucers, this episode delves into the mysterious world of UFOs. How our drive to explain these bizarre phenomena, and desire to discover little green men, has in fact transformed our understanding of the universe

Stephen Hawking is the most famous scientist on the planet. But behind the public face lies an argument that has been raging for almost 30 years. Has he been wrong for the last 30 years? Hawking shot to fame in the world of physics when he provided a mathematical proof for the Big Bang theory. This theory showed that the entire universe exploded from a singularity, an infinitely small point with infinite density and infinite gravity. Hawking was able to come to his proof using mathematical techniques that had been developed by Roger Penrose. These techniques were however developed to deal not with the beginning of the Universe but with black holes". Science had long predicted that if a sufficiently large star collapsed at the end of its life, all the matter left in the star would be crushed into an infinitely small point with infinite gravity and infinite density – a singularity. Hawking realised that the Universe was, in effect, a black hole in reverse. Instead of matter being crushed into a singularity, the Universe began when a singularity expanded to form everything we see around us today, from stars to planets to people. Hawking realised that to come to a complete understanding of the Universe he would have to unravel the mysteries of the black hole and its paradoxes

Inside the world-renowned physics laboratory Fermilab, a team of scientists are constructing an audacious experiment to hunt for a mysterious new ‘ghost’ neutrino. If they find it, this could transform our understanding of the nature and fabric of our universe. The problem is, these tiny particles are almost impossible to detect.
Elsewhere, physicists conduct experiments in some of the most extreme environments on the planet: from deep mine shafts in South Dakota to vast ice fields at the South Pole. In these unlikely places supersized neutrino detectors hope to unlock the universe’s deepest secrets. Could neutrinos overturn the most precise theory of particle physics that humans have ever written down? Could they even be a link to a hidden realm of new particles that permeate the cosmos – so called dark matter? Scientists at Fermilab are edging towards the truth.

The planets of our solar system have experienced epic catastrophes throughout their long history, both raining down from outside and bubbling up from within. We'll voyage back in time to investigate the violent events that profoundly shaped the planets, including earth itself. We'll witness stunning revelations about what transformed Mars into a barren, hostile desert... The disaster that changed Venus from temperate to hellish... The impact that blew away Mercury's mantle, turning it into a planetary core... A colossal disturbance that rearranged the orbits of the gas giants... Titanic impacts on Jupiter... And how a lost moon may finally explain Saturn's rings.

Is there anyone out there? Astronomers have been pointing their radio telescopes at the skies for decades trying to pick up alien signals, so far without success. But now there's a new way of looking for aliens. Hitch a ride with Dr Graham Philips as he joins astronomers trawling through the galaxy looking for signs of extra-terrestrial intelligence.

The Pythagorian philosopher Plato hinted enigmatically that there was a golden key that unified all of the mysteries of the universe. It is this golden key that we will return to time and again throughout our exploration. The golden key is the intelligence of the logos, the source of the primordial om. One could say that it is the mind of God. With our limited senses we are observing only the outer manifestation of the hidden mechanics of self similarity. The source of this divine symmetry is the greatest mystery of our existence.