What is the structure of a photon?

3 Answers
Jun 12, 2016

Physicists understood that it is not possible to investigate the inner structure of a fundamental particle because there is no "probe" to do a measurement.


Since the discovery of the quantum mechanics, physicists understood that it is not possible to investigate the inner structure of a fundamental particle. This mean that we have to treat the particles as point object without an internal structure. Unless we change the description of the word with a newer theory that for the moment does not exists.

It is impossible to define structure of a photon.


Photons are :

  • gauge bosons
  • massless
  • do not interact with the Higgs field

If you use a detector they can be visualized as the product of interactions between the EM field and the field making up particles of the detector.

Apr 21, 2017

Photons can be seen to have a form of structure.


Photons are complex as they are light quanta. They behave like both waves and like particles.

Maxwell's equations describe light as an alternating electric field and an alternating magnetic field travelling at the speed of light.

Einstein showed that the photon has a particle nature. A photon has no mass but has both energy and momentum. As it has no mass it must travel at the speed of light.

Quantum mechanics describe electric and magnetic fields as being caused be the exchange of virtual photons. So there is a strong connection between photons and electric and magnetic fields. Photons interact strongly with charged particles.

Other particles such as electrons also can behave like both particles and waves. Electrons are considered to be point particles with no size.

A photon doesn't behave like a point particle. They behave as if they have a size related to the wavelength. A good example of this is the mesh reflector. A microwave oven door has a metal mesh which prevents microwaves from escaping but allow light through so that you can watch the cooking process. This implies that the microwave photons are too big to pass through the mesh and are reflected. Having a size implies having a structure.

String theories describe photons as vibrating strings in 10 or 11 dimensional spacetime.

Our understanding of how things work is incomplete. New physics is required to unify quantum mechanics and gravity into a Theory of Everything. Such a theory would provide better insight into the nature of particles including the photon.