"The energy in the universe never increases or decreases -- but it does move around a lot. Energy can be potential (like a stretched-out rubber band waiting to snap) or kinetic (like the molecules that vibrate within any substance). And though we can't exactly see it, every time we cook dinner or shiver on a cold night, we know it's there. George Zaidan and Charles Morton get excited about energy." View the complete lesson at TED-Ed.