Are we alone? This is what Brian Cox asks in the third episode of his documentary Human Universe – an uneasy question not only because of its conspirational undertones. But the astrophysicist does not wax lyrical about UFOs or goes alien hunting, but remains with two feet squarely on the ground and answers the question in his usual rational and scientific manner. In contrast to the previous episode, this one is again much more solid and centers around the probability of life other than ours in the universe. There is much traveling to exotic locations and there are even swimming pigs, but this time it is all held together by a strong common theme.

Brian Cox begins in one of the most fascinating locations on Earth – Easter Island stands as a striking parallel for our planet in terms of isolation, one that has been breached on the island but not yet for us. The mysterious chants of Navajo Indians who communicate with the stars brings the episode to the Voyager spacecraft, on whose golden records those chants were included as emissaries to a potential alien civilization who might find them. SETI is, of course, next on Brian Cox’ travel destinations, aided by the voice of none other than Carl Sagan himself. He visits the Allen Array in California and has a look at the original printout of the famous Wow! Signal, demystifying the single ever signal received with the SETI network.

The highlight of the episode is an appearance Frank Drake, one of the founders of SETI and the creator of the Drake Equation. Carl Sagan and Neil deGrasse Tyson may have talked more in-depth about the formula, but Brian Cox had the chance to actually visit the charming astronomer, who in his mid-80s, is neither embittered or sad, but still optimistic that SETI will perhaps one day receive a signal. He admits that he is disappointed by the lack of results, but not surprised and is adamant that more searching with better technology is needed. He compares the short lifespan of a rare orchid from his greenhouse to the possibly fleeting existence of other civilizations in the universe and admits that getting a signal at the right time in the right place may be the biggest hurdle.

Next, Brian Cox makes a detour to South America to the ancient Inca civilization in the Peruvian highlands, who considered themselves the children of the sun. In the sacred valley, he visits the salt evaporation terraces on which the local people base their livelyhood, which would be impossible without the right climate – almost like life can only potentially arise on planets which are the habitable zone. Comparing the planets of our solar system, he arrives at the conclusion that there may once have been water on Mars and Venus long ago in addition to Earth, bringing the episode to the immense variety of stars in the Universe. In a wonderfully chaotic sequence, Brian Cox tries successfully to recreate the Hertzsprung-Russell diagram with a group of local Peruvian children holding round paper lampions.

The conclusion that there may be billions of potentially habitable star systems brings Brian Cox to the mission of the Kepler Space Telescope, which has already detected an almost four-digit amount of exoplanets and even some in the habitable zone. To the sounds of Chuck Berry, which are traveling on the Voyager records in interstellar space, one of the components of the Drake Equation turns Brian Cox to biology and the question of how common the spontaneous creation of life actually is. Diving in the Bahamas, he finds coral-like stromatolites which are similar to very early life on Earth and concludes that there may be at least simple life somewhere else in the Universe.

After the lovely diving sequence in the idyllic Bahamas and the conclusion that complex life first has to squeeze through a bottleneck of probabilities, it’s time for the funny animal sequence of the episode. There are no flying pigs, but at least swimming pigs from an uninhabited island in the Bahamas called appropriately Pig Bay, which serve as an example of the variety of life that can arise under the right conditions on an habitable planet. Continuing the biology theme, Brian Cox visits the Dolphin Research Center in Florida where one of their Bottlenose Dolphin exhibits definitive signs of intelligence, being able to recognize between different amounts of dots on signs as an example of gradually emerging intellect.

Back on Easter Island, Brian Cox compares the decline of the thousand-year-old civilization to the last part of the Drake Equation, the factor of the lifetime of a civilization. The episode concludes with the notion that colonization by self-replication machines á la John von Neumann may be a possible way of a civilization to survive at all odds. Before the last scene has one of the Voyager probes hurtling through space, Brian Cox ends with some stern, but hopeful warnings that humanity may indeed be unique in the universe and therefore has the duty to preserve itself in whatever way possible.

With even more beautiful visuals than the previous episode and much stronger storytelling, this effort from Brian Cox treads much more in the footsteps of his earlier series, literally bringing the sense of wonder back in an breathtaking, awesome way. It remains to be seen if the last two episodes will be as good as this one, but the titles Where are we? and What is our Future? sound very promising.

This episode was originally broadcast on Tuesday, October 21st on BBC2 and will be repeated on Sunday on the same channel at 8pm British time. For UK residents, it is also available on the iPlayer streaming service, but an airdate for North America on the co-producing Science Channel is still unknown. The DVD and Blu-Ray will be released on November 10th in England.

Brian Cox visiting Frank Drake.