In the third programme of the series, Aleks gives the lowdown on how, for better and for worse, commerce has colonized the web - and reveals how web users are paying for what appear to be 'free' sites and services in hidden ways. Joined by some of the most influential business leaders of today's web, including Eric Schmidt (CEO of Google), Chad Hurley (CEO of YouTube), Bill Gates, Martha Lane Fox and Reed Hastings (CEO of Netflix), Aleks traces how business, with varying degrees of success, has attempted to make money on the web. She tells the inside story of the gold rush years of the dotcom bubble and reveals how retailers such as Amazon learned the lessons. She also charts how, out of the ashes, Google forged the business model that has come to dominate today's web, offering a plethora of highly attractive, overtly free web services, including search, maps and video, that are in fact funded through a sophisticated and highly lucrative advertising system which trades on what we users look for. Aleks explores how web advertising is evolving further to become more targeted and relevant to individual consumers. Recommendation engines, pioneered by retailers such as Amazon, are also breaking down the barriers between commerce and consumer by marketing future purchases to us based on our previous choices. On the surface, the web appears to have brought about a revolution in convenience. But, as companies start to build up databases on our online habits and preferences, Aleks questions what this may mean for our notions of privacy and personal space in the 21st century

Part 2 examines how the freewheeling modernism that had shocked audiences in the first two decades of the century came under state control. Initially, many practitioners thought the totalitarian regimes would be good for music and the arts. What followed in Germany was a ban on music written by Jews, African-Americans and communists, while in the Soviet Union there was a prohibition on music the workers were unable to hum. After the cataclysm of the 1940s, a new generation of composers - Boulez, Stockhausen, Xenakis, Nono, Ligeti - turned their back on what they saw as the discredited music of the past and tried to reinvent it from scratch. Or, at least, from serialism, which became as much of a straitjacket as totalitarianism's strictures had been. But from this period of avant-garde experimentation, which many listeners found baffling and terrifying, came some of the most influential and radical musical innovations of the century.

Dr Michael Scott looks at the dramatic decline of Athens and the remarkable triumph and transformation of theatre. During the 4th century BC Athens would lose its Empire, its influence and even its democracy. But theatre, that most Athenian of inventions, would thrive, spreading throughout the Greek world and beyond and giving rise to a new kind of comedy, one so popular and prevalent that it is still at the heart of our comedy today.

It tells the story of FIFA World Cup of 1950, highlighting (but also showing other nations) the path of the two teams who played the final match: Uruguay and Brazil. The high quality of the footage is amazing, the text is smart and humorous, the music has been very well chosen in order to represent both the emotions involved in each moment and the contrast between the calmness of Uruguayan preparation and the crowded days of Brazilian team." The whole story shows not only one side. While Uruguayan team acquired confidence after an initial mistrust, Brazil was by far the best team in the competition but was heavily influenced by the environment in Brazilian society, the influence of politics and the pressure of the fans. While Uruguay overcame heroically all the constraints and, led by Obdulio Varela, won a title that few people believed, Brazilians got shocked because they considered themselves champions even before the final match, and their players became stigmatized until nowadays, not being celebrated as the fantastic team they were.

Ltes follow the development of some the biggest names in Rock in the 70s and 80s, among them Queen, Bruce Springsteen & The E Street Band, The Police and Dire Straits and shows how, through events such as Live Aid and the rise of MTV, rock achieved a global influence on culture and politics. The film concludes in the early 90s, as U2 effectively brought the era to a close by reinventing the big rock show.

The episode begins with Tyson describing how pattern recognition manifested in early civilization as using astronomy and astrology to predict the passing of the seasons, including how the passage of a comet was often taken as an omen. Tyson continues to explain that the origin of comets only became known in the 20th century due to the work of Jan Oort and his hypothesis of the Oort cloud. Tyson then continues to relate the collaboration between Edmond Halley and Isaac Newton in the last part of the 17th century in Cambridge. The collaboration would result in the publication of Philosophiæ Naturalis Principia Mathematica, the first major work to describe the laws of physics in mathematical terms, despite objections and claims of plagiarism from Robert Hooke and financial difficulties of the Royal Society of London. Tyson explains how this work challenged the prevailing notion that God had planned out the heavens, but would end up influencing many factors of modern life, including space flight. Tyson further describes Halley's contributions including determining Earth's distance to the sun, the motion of stars and predicting the orbit of then-unnamed Halley's Comet using Newton's laws. Tyson contrasts these scientific approaches to understanding the galaxy compared to what earlier civilizations had done, and considers this advancement as mankind's first steps into exploring the universe. The episode ends with an animation of the Milky Way and Andromeda galaxies' merging based on the principles of Newton's laws.