The conversion between matter and electromagnetic waves occurs at the quantum level and is governed by fundamental physical principles such as conservation of energy and conservation of momentum. The key concept that explains this transfer is wave-particle duality, which states that particles can exhibit both particle-like and wave-like properties.
On the smallest possible scale, matter particles such as electrons and positrons can exhibit wave-like behavior described by wavefunctions in quantum mechanics. Similarly, electromagnetic waves, such as photons, can be described as particles called quanta or photons.
When a particle and its corresponding antiparticle (e.g., an electron and a positron) come into close proximity, they can undergo an annihilation process. During annihilation, the particle and antiparticle collide, and their masses are converted into energy in the form of electromagnetic waves (photons). This process follows the principle of conservation of energy, where the total energy before and after the interaction remains constant.
Conversely, the conversion of electromagnetic waves into matter occurs through processes like pair production. In pair production, a high-energy photon interacts with an atomic nucleus or an atomic electron. Due to the energy of the photon, it is possible for the photon to create a particle-antiparticle pair (e.g., an electron and a positron) from the energy contained within the photon. This process also conserves energy, where the total energy before and after the interaction remains constant.
These phenomena are described mathematically by quantum field theories, such as quantum electrodynamics (QED), which is the theory that explains the interaction of electromagnetic fields and charged particles.
It's important to note that these processes occur at the quantum level and are not directly observable in our everyday macroscopic experiences. However, experiments and observations in particle physics and high-energy physics have provided significant evidence supporting these phenomena and their underlying theoretical frameworks.