Like how can any particle have no mass? Other particles like protons and electrons have mass, what’s so special about photons then?
In: Physics
Fundanental particles get their mass by interacting with the Higgs field.
Photons and gluons do not interact with the Higgs field, so they have no mass.
Photons are very special.
They have no rest mass, and only exist at a very high speed, and have angular momentum even though they have no mass or width. They are also their own anti-particle, as antimatter reactions produce photons that are identical to regular matter reaction photons.
It’s best not to think of particles as having mass or not having mass. E=mc^2 isn’t just saying that energy and mass are equivalent, it’s saying that mass is just a flavor of energy.
Some particles have mass, some don’t. They all have momentum.
E^2 = (pc)^2 + (mc^2 )^2 is the equation for relativistic energy-momentum. As mass, *m*, goes to zero for particles like the photon, it’s total energy is defined entirely by the momentum, *p*.
Mass dominates the total energy in nearly all trivial situations of massive bodies, driving the over-valuation of a particles mass to the casual observers. Understood, this equation shows the significance that momentum – obviously dominant in massless particle – can have. So it becomes not all that strange that some particles are massless, as they all have energy in varying forms.
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