Why are there so many subatomic particles?

Once upon a time it looked like particle physics would be neat and easy. Electrons & protons, neutrinos and neutrons, and some photons. All you need, right? read more

Physics is a tool for describing observations and making prediction about behavior that will be useful to engineers (and allow other physics to confirm or disprove existing theories). There is no"why" here, just observations that the above particles exist. read more

Because the mass of subatomic particles is so small, it is usually not measured in ounces or grams but in atomic mass units (label: amu) or electron volts (label: eV). An atomic mass unit is approximately equal to the mass of a proton or neutron. read more