View full lesson: http://ed.ted.com/lessons/dark-matter-the-matter-we-can-t-see-james-gillies
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.