Physics
Wave Motion
Quick fact
Waves can travel through a vacuum (like light from the sun) or through a material (like sound through air). The fastest known waves are electromagnetic waves, traveling at about 300,000 km/s in a vacuum.
Why this is interesting
You've seen ripples spread when you drop a pebble into a pond—but did you ever wonder why the water itself doesn't travel all the way to the edge? How does the energy move if the water mostly stays put?