The principles of Quantum Electrodynamics (QED) and relativity provide a framework to explain the behavior of particles at the quantum scale, combining quantum mechanics and special relativity. Here's a brief overview of how these principles come into play:
Quantum Mechanics: Quantum mechanics describes the behavior of particles at the microscopic level. It introduces the wave-particle duality, where particles can exhibit both wave-like and particle-like properties. The wave function represents the state of a particle, and its evolution is governed by the Schrödinger equation.
Special Relativity: Special relativity is a theory that describes the behavior of objects moving at high speeds, close to the speed of light. It introduces concepts like time dilation, length contraction, and the invariance of the speed of light in all inertial frames of reference.
Quantum Electrodynamics: QED is a specific quantum field theory that combines quantum mechanics and special relativity to explain the behavior of electromagnetic interactions, involving photons and charged particles (such as electrons). It is based on the principles of gauge symmetry and quantum fields.
In the context of QED, particles are considered excitations of quantum fields. For example, the electromagnetic field is quantized, and particles such as electrons and photons are treated as quanta of these fields. The behavior of particles and their interactions are described using Feynman diagrams, which depict the processes involving the emission, absorption, and scattering of particles.
QED provides a mathematical framework to calculate the probabilities of various interactions between particles and the associated amplitudes. These calculations take into account the wave-particle duality, the principles of quantum mechanics, and the effects of relativity. QED successfully explains phenomena such as the Lamb shift, the anomalous magnetic moment of the electron, and the interaction of charged particles with the electromagnetic field.
In summary, QED combines the principles of quantum mechanics and special relativity to explain the behavior of particles at the quantum scale, particularly with regard to electromagnetic interactions. It provides a robust mathematical framework that has been extensively tested and validated through experiments.