# Photon

A Photon is an elementary particle with zero rest mass that ...

**Context:**- It can have a Momentum.
- It can be a part of a Light Stream.
- It can be studied by Photonic Science.
- …

**Counter-Example(s):****See:**Quantum Cryptography, Bose–Einstein Statistics, Gauge Boson, Electromagnetism, Isospin, Total Angular Momentum, Parity (Physics), C Parity.

## References

### 2016

- (Wikipedia, 2016) ⇒ https://en.wikipedia.org/wiki/Photon Retrieved:2016-8-25.
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**photon**is an elementary particle, the quantum of all forms of electromagnetic radiation including light. It is the force carrier for electromagnetic force, even when static via virtual photons. The photon has zero rest mass and as a result, the interactions of this force with matter at long distance are observable at the microscopic and macroscopic levels. Like all elementary particles, photons are currently best explained by quantum mechanics but exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens and exhibit wave interference with itself, and it can behave as a particle with definite and finite measurable position and momentum. The photon's wave and quanta qualities are two observable aspects of a single phenomenon, and cannot be described by any mechanical model; a representation of this dual property of light, which assumes certain points on the wavefront to be the seat of the energy, is not possible. The quanta in a light wave cannot be spatially localized. Some defined physical parameters of a photon are listed. The modern concept of the photon was developed gradually by Albert Einstein in the early 20th century to explain experimental observations that did not fit the classical wave model of light. The benefit of the photon model was that it accounted for the frequency dependence of light's energy, and explained the ability of matter and electromagnetic radiation to be in thermal equilibrium. The photon model accounted for anomalous observations, including the properties of black-body radiation, that others (notably Max Planck) had tried to explain using*semiclassical models*. In that model, light was described by Maxwell's equations, but material objects emitted and absorbed light in*quantized*amounts (i.e., they change energy only by certain particular discrete amounts). Although these semiclassical models contributed to the development of quantum mechanics, many further experiments beginning with the phenomenon of Compton scattering of single photons by electrons, validated Einstein's hypothesis that*light itself*is quantized. In 1926 the optical physicist Frithiof Wolfers and the chemist Gilbert N. Lewis coined the name photon for these particles. After Arthur H. Compton won the Nobel Prize in 1927 for his scattering studies, most scientists accepted that light quanta have an independent existence, and the term*photon*was accepted.In the Standard Model of particle physics, photons and other elementary particles are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of particles, such as charge, mass and spin, are determined by this gauge symmetry. The photon concept has led to momentous advances in experimental and theoretical physics, including lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers, and for applications in optical imaging and optical communication such as quantum cryptography.

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### 2013

- http://spaceanswers.com/deep-space/if-photons-of-light-have-no-mass-how-can-space-be-bent-by-gravity/
- QUOTE: The first point to make is that while photons (little packets of light energy) do not have mass, they do have momentum, and a change in momentum yields a force, so in actual fact light is able to physically interact with matter. However, the key to this question came when Einstein developed his theory of general relativity. Photons of light are not technically affected by large gravitational fields; instead space and time become distorted around incredibly massive objects and the light simply follows this distorted curvature of space.