# Everybody knows that all physics systems absorb light quanta, any material thing can absorb light quanta. But the reverse question is , can light absorb energy and therefore changes its frequency? If not, please give me some fundamentals or equations that prohibit this from happening.

Everybody knows that all physics systems absorb light quanta, any material thing can absorb light quanta. But the reverse question is , can light absorb energy and therefore changes its frequency? If not, please give me some fundamentals or equations that prohibit this from happening.
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The process of inverse Compton scattering does exactly this. A photon can interact with a relativistic (ie. hot) electron, absorbs some of its energy, and emerges from the interaction with a higher frequency and energy. This has the effect of cooling the electrons. Roughly speaking, the new frequency is related to the original frequency by $\nu \sim {\gamma }^{2}{\nu }_{0}$, where $\gamma$ is the Lorentz factor of the electrons.
In astrophysics, this process can be an important source of very high energy photons (e.g. the interaction of radio waves with ultrarelativisic electrons in jets from active Galactic nuclei) and thus a significant cooling mechanism. An interesting piece of trivia is that because of inverse Compton scattering with cosmic microwave background photons, the maximum "lifetime" of any relativistic electron is about $2×{10}^{12}/\gamma$ years.