Photon momentum

Photon momentum refers to the idea that light, although made of particles called photons, can exert a force and carry momentum. Unlike massive objects, photons have no rest mass but still move at the speed of light, and their energy is related to their frequency. When photons interact with matter—such as reflecting off a surface—they transfer some of this momentum, exerting a small but measurable force. This concept is essential in understanding phenomena like solar sails for spacecraft, where sunlight's momentum pushes objects through space. Overall, photon momentum demonstrates that even massless particles can influence their surroundings through their energy and movement.