The earliest scientists first observed the waves that earthquakes produce before they could accurately describe the nature of earthquakes or their fundamental causes, as discussed in Lessons 1–5.

The waves you see at the shoreline are actually wind waves and are the sum of many components that were generated by the wind at a distant site. These components travel at different speeds, depending ...

For decades, physicists searched in vain for evidence of gravitational waves, the stretches and squeezes in spacetime that were first predicted by Albert Einstein’s theory of general relativity a ...

Introduction You may have heard that light consists of particles called photons. How could something as simple as light be made of particles? Physicists describe light as both a particle and a wave.