Photons, as massless particles, do not undergo a phase transition into a liquid or solid state like other bosons such as gluons and Higgs bosons. The distinction arises from the fundamental properties of the particles and the underlying physics governing their behavior.
The condensation of particles into a gas, liquid, or solid state is associated with the formation of bound states or the emergence of collective behavior due to attractive interactions between the particles. In the case of bosons, like gluons and Higgs bosons, these interactions can give rise to a phase transition, leading to the formation of a condensed state with mass and other emergent properties.
However, photons, being massless, do not possess the same type of attractive interactions that would allow for a phase transition into a condensed state. Photons are associated with the electromagnetic force, and they do not directly interact with each other through the electromagnetic interaction. Instead, photons interact with charged particles, such as electrons and protons, through electromagnetic interactions.
In a system of photons, these interactions are characterized by the phenomenon of scattering, where photons change their direction or energy by interacting with charged particles. These interactions do not result in the formation of bound states or the emergence of collective behavior that would lead to the condensation of photons into a liquid or solid state.
It's important to note that while photons do not condense into a liquid or solid, they can exhibit interesting collective behavior in certain systems. For example, in phenomena like lasing or Bose-Einstein condensation of photons in certain materials, photons can display some characteristics of a "photon gas" with coherent behavior. However, this behavior is different from the phase transitions observed in other bosonic systems.
In summary, the absence of attractive interactions between photons prevents them from undergoing a phase transition into a condensed state like a liquid or solid, unlike other bosons such as gluons and Higgs bosons.