If light has energy but no mass, how can it have momentum?

Question

If light has energy but no mass, how can it have momentum?

In: 55

Answer 1

Some great explanations here, but most are way more complex than I could explain to my 5-year-old. How about this:

Photons (light) are often described as having the properties of both particles and waves. For the momentum piece, let’s focus on waves. **Picture a wave in the ocean:** It travels across the ocean with an observable momentum, however the drops of water do not travel with it. The photon of light travels across the electromagnetic field similarly to how the ocean wave travels across the surface of the water.