In this historical speech, Barack Obama speaks of the greatness of the multiculturalism of the United States of America, and how it is a tool that will help us overcome all difficulties.

Abi tells us a little about the history of the origami paper crane, from its significance in Japanese culture to her own personal contact with this powerful modern symbol of hope and goodwill.

The trolley problem is a classic thought experiment in moral philosophy. Is sacrificing one life to save the lives of many others the best possible outcome?

Plato is considered one of Philosophy’s greatest writers. He was able to conceive of greater realities by imagining how much poorer our perception would be if we had lived our whole life as prisoners locked in a cave.

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.

This ancient mathematical trickery posits that a mighty hero cannot overtake a tortoise. Zeno of Elea (born c. 490 BCE) is the author of this and other paradoxes.

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.