Aliens almost certainly do exist. So why haven't we yet met E.T.? It turns out we're only just developing instruments powerful enough to scan for them, and science sophisticated enough to know where to look. As a result, race is on to find the first intelligent aliens. But what would they look like, and how would they interact with us if we met? The answers may come to us sooner than we imagine, for one leading astronomer believes she may already have heard a hint of their first efforts to communicate

What sort of alien civilizations might exist in the vastness of space? Terra is the fictional world imagined in Episode 4, a planet nine billion years old, twice as old as Earth. Old enough that a truly advanced intelligence could evolve. It was once a fertile world, now it is barren. But life can still thrive here in artificial domes. Over time, they've evolved not to need their bodies. They exist only as neural tissue. They never age, they never die. They're monitored and maintained by robots.
If alien civilizations are statistically so likely, why haven't astronomers found any sign of them? Where is everyone? Every time we look at an individual star, that's like dropping a bucket in the ocean. We're going to have to look at a lot of stars and to search through a lot of data until we find the clue that leads us to another civilization.

From fears about work and privacy to a rivalry between the U.S. and China, the series explores the promise and perils of AI. It traces a new industrial revolution that will reshape and disrupt our lives, our jobs and our world, and allow the emergence of the surveillance society.
Today, China leads the world in e-commerce and is a society that bypassed credit cards. Now shops in stores are without cashiers, where the currency is facial recognition. No country has ever moved that fast. And in a short two-and-a-half years, China's A.I. implementation really went from minimal amount to probably about 17 or 18 unicorns, that is, billion-dollar companies. The progress was powered by a new generation of ambitious young techs pouring out of Chinese universities, competing with each other for new ideas, and financed by a new cadre of Chinese venture capitalists.

In the 1960s and 1970s a generation of Mexican Americans, frustrated by persistent discrimination and poverty, find a new way forward, through social action and the building of a new "Chicano" identity. The movement is ignited when farm workers in the fields of California, led by Cesar Chavez and Dolores Huerta, march on Sacramento for equal pay and humane working conditions. Through plays, poetry and film, Luis Valdez and activist Corky Gonzalez create a new appreciation of the long history of Mexicans in the South West and the Mestizo roots of Mexican Americans. In Los Angeles, Sal Castro, a schoolteacher, leads the largest high school student walkout in American history, demanding that Chicano students be given the same educational opportunities as Anglos. In Texas, activists such as Jose Angel Gutierrez, create a new political party and change the rules of the electoral game. By the end of the 1970s Chicanos activism and identity have transformed what it means to be an American. Chicano and Latino studies are incorporated into school curriculum; Latinos are included in the political process.

Astrology, the celestial movements of the Sun, Moon, and planets among the stars, governing our personality and destiny. For centuries, millions of people, from paupers to powerful world leaders, have relied on the ancient system for answers. This episode examines whether tracking astronomical phenomena can actually predict the future.

'Deliver Us from Drought' - Over the past years, Texas has experienced the worst drought in its recorded history. 97% of the scientific community agrees that human activity has contributed to extreme weather patterns around the world. But many Texans--legislators, community leaders and citizens--don't attribute their drought to humans, and have taken few if any initiatives to limit the state's CO2 emissions, currently the highest in the country. "The Resource Curse" - As humanity's appetite for energy grows exponentially, the extraction industry scrambles to the most remote regions on Earth. In the undeveloped Melanesian country of Papua New Guinea, America's Exxon Mobil has staked its claim to a $19 billion liquid natural-gas project. While some see Exxon's mammoth presence as the catalyst that will usher the underdeveloped country into the 21st Century, others predict the initiative could plunge its people into civil war.