The Greeks had a simple and elegant formula for the universe: just earth, fire, wind, and water. Turns out there’s more to it than that — a lot more. Visible matter (and that goes beyond the four Greek elements) comprises only 4% of the universe. CERN scientist James Gillies tells us what accounts for the remaining 96% (dark matter and dark energy) and how we might go about detecting it.

Lesson by James Gillies, animation by TED-Ed.

English philosopher John Locke wrote in An Essay Concerning Human Understanding in 1693 that "the highest perfection of intellectual nature lies in a careful and constant pursuit of true and solid happiness." This concept, which is among the founding principles of the U.S. Declaration of Independence, has long been studied by philosophers and psychologists. But what is happiness? Can happiness be pursued? And how can a person become happier? Dr. Sheldon will address these and other questions in his lecture.