This episode explores the wave theory of light as studied by mankind, noting that light has played an important role in scientific progress, with such early experiments from over 2000 years ago involving the camera obscura by the Chinese philosopher Mozi. Tyson describes the work of the 11th century Arabic scientist Ibn al-Haytham, considered to be one of the first to postulate on the nature of light and optics leading to the concept of the telescope, as well as one of the first researchers to use the scientific method. Tyson proceeds to discuss the nature of light as discovered by mankind. Work by Isaac Newton using diffraction through prisms demonstrated that light was composed of the visible spectrum, while findings of William Herschel in the 19th century showed that light also consisted of infrared rays. Joseph von Fraunhofer would later come to discover that by magnifying the spectrum of visible light, gaps in the spectrum would be observed. These Fraunhofer lines would later be determined to be caused by the absorption of light by electrons in moving between atomic orbitals when it passed through atoms, with each atom having a characteristic signature due to the quantum nature of these orbitals. This since has led to the core of astronomical spectroscopy, allowing astronomers to make observations about the composition of stars, planets, and other stellar features through the spectral lines, as well as observing the motion and expansion of the universe, and the existence of dark matter.

Researchers discuss mythic ancient treasure and curses including King Solomon's Ring, lost Aztec treasure, and the Omphalos.

A visually stunning journey to the end of the world with the hardy and devoted people who live there year-round. The research stations scattered throughout the continent host a close-knit international population of scientists, technicians and craftsmen. Isolated from the rest of the world, enduring months of unending darkness followed by periods when the sun never sets, Antarctic residents experience firsthand the beauty and brutality of the most severe environment on Earth. Capturing epic battles against hellacious storms, quiet reveries of nature's grandeur, and everyday moments of work and laughter, this unique documentary shows a steadfast community thriving in a land few humans have experienced. Using specially modified cameras and spectacular time-lapse photography, filmmaker Anthony Powell captures the splendor of the region like no film before. ANTARCTICA: A YEAR ON ICE gives testament to the planet's natural wonders, humanity's thirst for adventure, and the emotional extremes that accompany a year within the last pristine wilderness on the planet.

Black Holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question - what was there before the Big Bang? The trouble is that researching them is next to impossible. Black holes are by definition invisible and there's no scientific theory able to explain them. Meet the astronomers attempting to image a black hole for the very first time and the theoretical physicists getting ever closer to unlocking their mysteries. It's a story that takes us into the heart of a black hole and to the very edge of what we think we know about the universe.

Researchers discover film footage from World War II that turns out to be a lost documentary shot by Alfred Hitchcock and Sidney Bernstein in 1945 about German concentration camps liberated by allied troops. When Allied forces liberated the Nazi concentration camps in 1944-45, their terrible discoveries were recorded by army and newsreel cameramen, revealing for the first time the full horror of what had happened. Making use of British, Soviet and American footage, the Ministry of Information’s Sidney Bernstein (later founder of Granada Television) aimed to create a documentary that would provide lasting, undeniable evidence of the Nazis’ unspeakable crimes. He commissioned a wealth of British talent, including editor Stewart McAllister, writer and future cabinet minister Richard Crossman – and, as treatment advisor, his friend Alfred Hitchcock. Yet, despite initial support from the British and US Governments, the film was shelved, and only now, 70 years on, has it been restored and completed by Imperial War Museums. This eloquent, lucid documentary by André Singer (executive producer of the award-winning The Act of Killing) tells the extraordinary story of the filming of the camps and the fate of Bernstein’s project, using original archive footage and eyewitness testimonies.

A feature length documentary about humanity's absolute dependence on animals (for pets, food, clothing, entertainment, and scientific research) but also illustrates our complete disrespect for these so-called 'non-human providers'. With an in-depth study into pet stores, puppy mills and animals shelters, as well as factory farms, the leather and fur trades, sports and entertainment industries, and finally the medical and scientific profession, the film uses hidden cameras and never before seen footage to chronicle the day-to-day practices of some of the largest industries in the world, all of which rely entirely on animals for profit. Powerful, informative and thought-provoking, EARTHLINGS is by far the most comprehensive documentary ever produced on the correlation between nature, animals, and human economic interests. There are many worthy animal rights films available, but this one transcends the setting.