Military laser experiment.jpg 

Composition Elementary particle
Statistics Bosonic
Group Gauge boson
Interactions Electromagnetic
Symbol γ, hν, or ħω
Theorized Albert Einstein
Mass 0
<1×10−18 eV/c²[1]
Mean lifetime Stable[1]
Electric charge 0
<1×10−35 e[1]
Spin 1
Parity -1[1]
C parity -1[1]
Condensed I(JPC) = 0,1(1)[1

In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are currently best explained by quantum mechanics and will exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when quantitative momentum (quantized angular momentum) is measured.

The modern concept of the photon was developed gradually byAlbert Einstein to explain experimental observations that did not fit the classical wave model of light. In particular, the photon model accounted for the frequency dependence of light’s energy, and explained the ability of matter and radiation to be in thermal equilibrium. It also accounted for anomalous observations, including the properties of black body radiation, that other physicists, most notably Max Planck, had sought to explain using semiclassical models, in which light is still described by Maxwell’s equations, but the material objects that emit and absorb light are quantized. Although these semiclassical models contributed to the development of quantum mechanics, further experiments[citation needed] validated Einstein’s hypothesis that light itself is quantized; the quanta of light are photons.

In the Standard Model of particle physics, photons are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of photons, such as chargemass and spin, are determined by the properties of this gauge symmetry. The neutrino theory of light, which attempts to describe the photon as a composite structure, has been unsuccessful so far.

The photon concept has led to momentous advances in experimental and theoretical physics, such as lasersBose–Einstein condensationquantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied tophotochemistryhigh-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers and for sophisticated applications in optical communication such as quantum cryptography.



About FreeEnergyMan

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