photon

[ foh-ton ]

noun

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

photon

/ 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

photon

/ 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 radiationSee Table at subatomic particle

photon

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

Word History and Origins

Origin of photon¹

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

Example Sentences

In a paper published last week in Science, the researchers describe firing a single photon at one of their qubits, which reflects it and in the process becomes entangled with it.

From Singularity Hub 

The photons were sent to two locations a kilometer apart, researchers from Nanjing University in China report in a study to appear in Physical Review Letters.

From Science News

A second layer with a slightly different chemical makeup creates a reflective barrier that will prevent photons from escaping as they bounce down the pipe, which acts as a waveguide.

From Popular-Science

Determining where the photons end up requires solving a mess of equations brimming with unknowns.

From Singularity Hub 

Finally, the number of photons in each of the network’s output channels is measured at the end.

From Science News

When the gamma rays enter the sleeve, they interact with that photon gas, annihilating into electron-positron pairs.

From The Daily Beast

Gregory Breit and John Archibald Wheeler first predicted this photon-photon annihilation in 1934.

From The Daily Beast

The medicine worked because the photon–the quantum bundle of light and the carrier of the electromagnetic force–has no mass.

From The Daily Beast

Among his pastimes was designing a solar-power car, the Photon Torpedo.

From The Daily Beast

Or, the photon may be retained for a while and emitted again relatively unchanged—the effect observed in luminous paint.

From Project Gutenberg

"I think I am getting somewhere on my photon-neutrino-electron interchange-cycle," he announced.

From Project Gutenberg

Or there may be an inelastic collision, when the photon hits an atom and knocks out an electron—the old photoelectric effect.

From Project Gutenberg

"Well, you know what happens when a photon comes in contact with the atomic structure of matter," Kato said.

From Project Gutenberg

There were hundreds of scintillations, each caused by a nuclear particle or photon striking the screen.

From Project Gutenberg