Do Particles and Antiparticles Have the Same Mass?

The CPT Theorem and Its Implications

Yes, particles and antiparticles have the same mass in a rigorous quantum framework. This is enforced by the CPT theorem (Charge-Parity-Time theorem). The CPT theorem states that the quantum laws are the same when:

Charge is inverted (changing particles to antiparticles) Parity is inverted (flipping the orientation of space) Time is inverted (reversing the direction of time)

This theorem ensures that particles and their corresponding antiparticles must have the same mass. However, other properties like charge and magnetic moment can differ, but the mass remains the same.

Rest Mass Conservation

When discussing rest mass, particles and their anti-particles typically share the same mass, except in certain cases. For example, the rest mass of a proton is the same as that of an antiproton, but the rest mass of a proton is different from that of an anti-neutron. This rest mass equivalence is fundamental to the behavior of subatomic particles in the universe.

Positrons and Electron Antiparticles

Positrons, being the antiparticles of electrons, share the same mass but have an opposite charge. An electron has a mass of approximately 1/2000 the mass of a proton and a negative charge. A positron, having the same rest mass, will have a positive charge. This equivalence in mass underpins the duality of matter and antimatter.

Antimatter and the Early Universe

A fundamental difference between matter and antimatter lies in their electric charge and magnetic moment properties. Matter and antimatter are considered equivalent in all respects except for their electromagnetic charge. This means that an electron and a positron have the same mass but opposite charges. This property is crucial to understanding their behavior and the balance observed in the universe.

According to theoretical physicists like P. Dirac, Feynmann, and others, matter and antimatter's behavior is influenced by the direction of time. The early universe had a slight preference for matter over antimatter, leading to a universe with a significant mass composed of matter. Most antimatter, upon encountering matter, annihilates and emits gamma rays, leaving very little antimatter in our observable universe.

Observational Evidence and Annihilation Phenomenon

Observational evidence supports the concept that antimatter and matter are mass-equivalent. An electron and a positron, for instance, have the same mass but opposite electric charges, exemplifying this equivalence. Understanding the properties and behavior of antimatter, especially in close association with matter, is critical to modern particle physics and cosmology. The inability of matter and antimatter to coexist for extended periods due to their mutual annihilation is a fascinating aspect of the universe's fundamental forces.

For a deeper insight into these concepts, further reading and research into the CPT theorem, particle physics, and cosmology would be beneficial.