You and your team of scientists are trapped on Mars. Can you figure out how to survive on the desert planet? -- Today is the anniversary of the best-worst day of your life. The best part was discovering a subterranean city on Mars. The worst part was when you lost contact with Earth. You and ...

View full lesson: http://ed.ted.com/lessons/can-you-solve-the-prisoner-hat-riddle-alex-gendler Want more? Try the buried treasure riddle: https://www.youtube.com/watch?v=tCeklW2e6_E You and nine other individuals have been captured by super-intelligent alien overlords. The aliens think humans ...

Stand by for an animated exploration of the famous Fermi Paradox. Given the vast number of planets in the universe, many much older than Earth, why haven't we yet seen obvious signs of alien life? The potential answers to this question are numerous and intriguing, alarming and hopeful. source