What is a photon? The definition of the photon would happen to say that it is a certain particle of light that propagates in a vacuum. Basically, the photon is the particle from which the quantum manifestations of the electromagnetic phenomenon arise. The photon is the one that carries from one point to another the electromagnetic radiation, in its diverse forms of presentation.

A photon is an elementary particle, in which all forms of electromagnetic radiation converge. Also light. When we talk about the forms of electromagnetic radiation, we speak from microwaves to gamma rays, through x- rays, infrared light, radio waves or ultraviolet light. There are many others, but these are the most common. The photon is the one in charge of tertiary with the electromagnetic force.

It is not easy to answer what a photon is or the definition of a photon. And the terminology in this sector is not the one that is handled daily. Still, we will say that a photon, by having a mass that is not altered, can travel through the vacuum at a constant speed. For this reason, a photon can be analyzed both microscopically and macroscopically.

And above all, doing so while maintaining its corpuscular and wave properties, which allow it to act as if it were a wave. At least, in special circumstances such as when refracting a slow. In turn, the photon will remain a particle, as long as it maintains its amount of unaltered energy when it reaches the material.

For example, a lens can reflect a single photon and, during the refractory process, interfere with itself as if it were a wave. In the same way, it would not stop being a particle with a very specific position and a quantity of movement that we could quantify. And, both the wave and quantum properties of the photon can be measured in a single phenomenon. Of course, photons cannot be located in space.


It was Albert Einstein who named the photons, yes, it was not the name he gave them but the quantity of light. It was the early twentieth century and with these light quanta, Albert Einstein sought to explain experimental observations that did not fit in his investigations of the usual model of light as an electromagnetic wave.

Einstein's redefinition of the quantum of light or photon, established and accepted that the energy of light was dependent on its frequency, in addition to giving truth to the fact that matter and electromagnetic radiation maintained a thermal balance between them. The thing was not there. The new photon concept also addressed anomalous observations of the caliber of blackbody radiation.

An explanation that had resisted the majority of physicists, or that had been impossible to expose using the well-known semiclassical models. For example, Max Planck, a renowned physicist, defined light by means of Maxwell's equations. The problem was that the light is thrown and assumed by material objects that came in small groups of energy.

Although these investigations were the basis of quantum mechanics, it was demonstrated, after a short time, that Albert Einstein's hypothesis was correct. Without going any further, through the effect of Compton.

Years later, in 1926, the physicist Gilbert Lewis, in the company of the optical physicist Frithiof Wolfers, would be the ones who would change the concept of quanta of light to the current concept of the photon, which has remained to this day. The term photon is taken from the Greek word that precisely means light and comes to the hair.

A year later, and after being awarded the Nobel Prize in Physics to Arthur H. Compton, thanks to his theories on dispersion, the scientific community embraced the fact that light quanta existed independently. In addition, they accepted the term photon to replace the quantum of light.

What's more, in physics, when speaking of photons, the Greek letter gamma is used to mention them. It seems logical that if the gamma rays come from the photons, and the origin of the name of these is Greek, the Greek tradition will continue.

However, things change when we talk about chemistry. Even of optical engineering. In this case, the photons are marked by the symbol hv. These two letters come to mark the energy associated with each photon. A photon that, as we have already mentioned, does not have its own mass, but does not have any electrical charge either. For this reason, when it comes into contact with the vacuum, it does not disappear immediately.

The ways in which photons are emitted are as common as they are natural. Without going any further, when a particle is accelerated by an electrical charge during a molecular transition. Another valid example is the moment in which we are ready to make a particle disappear, applying its antiparticle.

This model, already standardized around photons, is given by the fact that the laws of physics are almost symmetrical in space and time. Elements of particles, such as mass or electrical charge, are marked by this symmetry. Thus, photons have been applied to sectors such as high-resolution microscopy, photochemistry or the measurement of molecular distances. A work that began more than a century ago, but that continues giving yields and advances to science, from the hand of a pioneer like Albert Einstein.