fotonene

Photons are the quanta of the electromagnetic field. They are massless bosons that travel at the speed of light in vacuum and interact with charged matter through the electromagnetic force. Each photon carries energy proportional to its frequency, E = hν, and momentum p = hλ = hν/c. With m = 0, the energy–momentum relation reduces to E = pc.

In quantum theory they exhibit wave–particle duality: they show interference and diffraction as waves while arriving as discrete energy quanta during emission or absorption. Photons also carry angular momentum and have polarization states corresponding to a spin of 1.

Production and detection: photons are emitted by atomic or molecular transitions, thermal radiation, or nonlinear optical processes, and are absorbed when their energy matches a transition. They are detected by photodiodes, photomultiplier tubes, or CCDs, which convert light into electrical signals.

Statistics and thermodynamics: photons obey Bose–Einstein statistics, and in thermal equilibrium their chemical potential is zero. A photon gas follows Planck’s blackbody spectrum.

Applications: photons underpin optical communications, lasers, imaging, spectroscopy, and quantum information processing through single-photon sources and entangled states.

Linguistic note: in Norwegian, fotonen is the singular and fotonene the definite plural form meaning the photons.

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