photon

American  

[foh-ton] / ˈfoʊ tɒn /

noun

• photons
  plural

1. a quantum of electromagnetic radiation, usually considered as an elementary particle that is its own antiparticle and that has zero rest mass and charge and a spin of one. γ

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photon British  

/ ˈfəʊtɒn /

noun

1. a quantum of electromagnetic radiation, regarded as a particle with zero rest mass and charge, unit spin, and energy equal to the product of the frequency of the radiation and the Planck constant

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photon Scientific  

/ fō′tŏn′ /

1. The subatomic particle that carries the electromagnetic force and is the quantum of electromagnetic radiation. The photon has a rest mass of zero, but has measurable momentum, exhibits deflection by a gravitational field, and can exert a force. It has no electric charge, has an indefinitely long lifetime, and is its own antiparticle.

2. See Note at electromagnetic radiation See Table at subatomic particle

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photon Cultural  

1. The quantum, or bundle of energy, in which light and other forms of electromagnetic radiation are emitted. (See atom.)

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Other Word Forms

Noun Inflected Forms

• photons
  plural

Etymology

Origin of photon

First recorded in 1900–05; phot- + -on ¹

Explanation

In physics, a photon is a tiny bundle of matter that transmits light. You can also think of photons as little bits of electromagnetic energy. Light is made up of small amounts of energy which are known as photons. You can tell how much radiation is being emitted by the number of photons — think of a dimmer on a light switch, with the brighter light emitting more photons. Albert Einstein was instrumental in developing the photon theory of light, although he used the term "the light quantum," rather than photon, which was first used in this sense around 1926.

Example Sentences

See Examples For:

photon photons

A system involving only a modest increase in photon number can therefore demand dramatically more measurements.

From Science Daily ● Sep. 29, 2026

The dark photon search produced an especially intriguing result.

From Science Daily ● Sep. 6, 2026

For GlueX, the two unexpected signals may mark the beginning of a much broader exploration of exotic hadrons using high-energy photon beams.

From Science Daily ● Sep. 2, 2026

"We went searching for a confirmed XYZ candidate with a photon beam but instead found two other structures," said Malte Albrecht, a staff scientist at Jefferson Lab.

From Science Daily ● Sep. 2, 2026

Equally, if a real photon collides with an atom, it may move an electron from an orbit nearer the nucleus to one farther away.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

When these charged particles collide with oxygen and nitrogen, photons of coloured light are emitted - this is the aurora.

From BBC ● Oct. 10, 2026

Their interpretation suggests that the superconducting state exchanges virtual photons with the dark cavity.

From Science Daily ● Oct. 3, 2026

By sending three individual photons into the device with carefully selected polarization states, the researchers showed that the system could distinguish among different types of three-photon W states.

From Science Daily ● Sep. 29, 2026

Many think there's an even better way of doing that, using light in the form of photons.

From BBC ● Sep. 22, 2026

Again, the photons that are exchanged are virtual particles.

From "A Brief History of Time: And Other Essays" by Stephen Hawking