The more you think about it, the more complex time travel seems! This video explains a key paradox that is one of the main reasons for this.

John Searle's thought experiment, called "The Chinese Room," presents an argument against the idea that computers could ever be truly intelligent.

If a hotel with an infinite number of rooms has an infinite number of guests, how could it free up space when new guests arrive? Hilbert's “Grand Hotel” paradox has fascinated mathematicians, physicists, philosophers, and theologians, as it encourages another way of thinking about the notion of infinity.

How can one brother travel into space and return younger than his twin? In just sixty seconds, a startling side effect of Einstein’s Theory of Relativity is explained to us.

Schrodinger’s hypothetical experiment involved putting an unfortunate cat into a box with a Geiger counter and a vial of deadly poison. Until the box was opened, the cat could be said to be alive, or dead… or possibly in both of these states simultaneously.

The philosopher Friedrich Nietzsche questioned the ability of science to explain and give meaning to our world, daring us to think critically not only about religion, but science, and knowledge itself. Learn all about his ideas in this fun video inspired by vintage video games.

The BBC looks at a new and innovative renewable energy invention, Kite Power Solutions. It is estimated that 30 kites could provide electricity for 75,000 homes.

By following honeyguides, a species of bird, people in Africa are able to locate bees’ nests to harvest honey. Research now reveals that humans use special calls to solicit the help of honeyguides and that honeyguides actively recruit appropriate human partners. This relationship is a rare example of cooperation between humans and free-living animals.

Fuse School: Learn the basics about the effects of global warming on the environment. Some of the problems global warming may cause are changing climate, extremes of weather, problems for ecosystems, rising sea levels, and ocean acidification.

The earth's bodies of water are the focus of this film about evolution. As the narrator points out, the vast depths of the earth's oceans remain barely explored.

Corals are sessile animals, meaning they are immobile and anchored to one spot for the entirety of their lives. Stony coral, leathery coral, and sea fan coral are featured in this segment, along with the beautiful fish that inhabit coral reefs.

Brilliantly colorful parrot fish and two-bar sea bream are among the fish featured in this segment. Sea cucumbers, the vacuum cleaners of all the Earth's oceans, also make an appearance.

This segment looks at the advantages and disadvantages of swarm fish and loner fish, providing insight into their coloration and behavior. Spectacular footage reveals twobar sea bream, trumpet fish, barracudas, and harlequin sweetlips.

Green sea turtles (the largest hard-shelled sea turtle) and whale sharks (the largest shark and fish overall) are featured in this segment. We also encounter a langouste, otherwise known as a rock lobster, and a moray eel lurking in their coral reef habitat.

We learn about the thousands of kilometers that humpback whales travel from their summer habitat in the polar regions to the tropical or subtropical waters where they spend the winter. Their multi-versed songs and the markings on their flukes are also discussed.