What is the structure of a photon?

Physicists have known since the discovery of quantum mechanics that it is not possible to study the internal structure of a fundamental particle; instead, we must treat particles as point objects devoid of an internal structure, unless we modify the description of the word with a more recent theory, which is currently nonexistent.

The photon is:

When using a detector, they can be seen as the result of interactions between the detector's particle-forming field and the electromagnetic field.

Being light quanta, photons exhibit complex behavior, exhibiting characteristics of both waves and particles.

According to Maxwell's equations, light is composed of two alternating magnetic and electric fields that move at the speed of light.

A photon has momentum and energy but no mass, so it must move at the speed of light. Einstein demonstrated the particle nature of the photon.

There is a strong correlation between photons and electric and magnetic fields because photons interact strongly with charged particles, as described by quantum mechanics, and electric and magnetic fields are generated by the exchange of virtual photons.

Other particles, like electrons, which are thought of as point particles devoid of size, can also behave in both particle and wave forms.

Instead of acting like a point particle, a photon behaves as though it has a size that is proportional to its wavelength. A good example of this is the mesh reflector found in microwave oven doors, which are made of metal and let light through while keeping microwaves from escaping. This suggests that the microwave photons are too large to fit through the mesh and are reflected, meaning that having a size implies having a structure.

Photons in 10 or 11 dimensional spacetime are described as vibrating strings in string theories.

In order to bring quantum mechanics and gravity together into a Theory of Everything—which would provide us a better understanding of the nature of particles, including the photon—new physics is needed.

As the quanta of light and electromagnetic radiation, photons are fundamental particles and are regarded as elementary particles. Unlike atoms or molecules, photons do not have an internal structure or size; instead, they are described as point-like particles based on current physics knowledge.