How can a Photon apparently transfer Momentum without any Mass?

AI Thread Summary
Photons, despite being massless, can transfer momentum due to their energy and the principles of relativistic physics. The relationship between energy, momentum, and mass is defined by the equation E² = (pc)² + (mc²)², where for photons, the mass (m) is zero. This means that photons possess momentum, represented as p = E/c, allowing them to affect other particles, such as electrons, during interactions like Compton scattering. The discussion emphasizes that in relativistic contexts, momentum can exist independently of mass. Understanding this concept is crucial for grasping the behavior of light and its interactions in physics.
KBon
Due to Compton - Scattering it seems that a Photon changes the Momentum of the electron, although it doesn't have any mass. How should I imagine this?
 
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A photon is massless but has energy and momentum. It's the mode of an electrodmagnetic field, and you have
$$E=|\vec{q}|c,$$
where ##\vec{q}## is the momentum of the photon.

In relativistic physics you don't need a mass to have a momentum!
 
Relativistically, the general relationship between energy, momentum, and mass is ##E^2 = (pc)^2 + (mc^2)^2## where p is the magnitude of the momentum. For a photon, m = 0 which gives vanhees71's formula, in different notation.
 
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