In the fourth episode, Professor Marcus du Sautoy concludes his investigation into the history of mathematics with a look at some of the great unsolved problems that confronted mathematicians in the 20th century. After exploring Georg Cantor's work on infinity and Henri Poincare's work on chaos theory, he sees how mathematics was itself thrown into chaos by the discoveries of Kurt Godel and Paul Cohen, before completing his journey by considering some unsolved problems of maths today, including the Riemann Hypothesis.

Zeitgeist Addendum attempts to locate the root causes of this pervasive social corruption, while offering a solution. This solution is not based on politics, morality, laws, or any other 'establishment' notions of human affairs, but rather on a modern, non-superstitious based understanding of what we are and how we align with nature, to which we are a part. The work advocates a new social system which is updated to present day knowledge, highly influenced by the life long work of Jacque Fresco and The Venus Project.

Filmmaker Jonathan Reiss offers a multilingual look at the evolution of graffiti in a documentary that begins by examining ancient rock paintings and traces the trend straight through to the works of Picasso and 1970s-era New York City hip-hop culture. Shot on five continents using guerilla filmmaking techniques, Bomb It aims to give viewers a newfound appreciation of graffiti culture by exploring the origins of street art and interviewing the artists about their tactics and motivations.

Political humorist and author Bill Maher travels around the globe interviewing people about God and religion. Known for his analytical skills, wit and commitment to never pulling a punch, Maher brings his characteristic honesty to an unusual spiritual journey.
Muslims, Jews and Christians of many kinds pass before his jaundiced eye. He goes to a Creationist Museum in Kentucky, which shows that dinosaurs and people lived at the same time 5000 years ago. Maher speaks to a rabbi in league with Holocaust deniers. He talks to a Muslim musician who preaches hatred of Jews. Maher finds the unlikeliest of believers and, in a certain Vatican priest, he even finds an unlikely skeptic.

brilliant mathematicians, whose genius has profoundly affected us, but which tragically drove them insane and eventually led to them all committing suicide. Georg Cantor, the great mathematician whose work proved to be the foundation for much of the 20th-century mathematics. He believed he was God's messenger and was eventually driven insane trying to prove his theories of infinity. Ludwig Boltzmann's struggle to prove the existence of atoms and probability eventually drove him to suicide.

brilliant mathematicians whose genius has profoundly affected us, but which tragically drove them insane and eventually led to them all committing suicide. Kurt Gödel, the introverted confidant of Einstein, proved that there would always be problems which were outside human logic. His life ended in a sanatorium where he starved himself to death. Finally, Alan Turing, the great Bletchley Park code breaker, father of computer science and homosexual, died trying to prove that some things are fundamentally unprovable.