Electron-electron interaction

• One way to think about electron-electron interaction is to imagine two people throwing balls at each other. If one person throws a ball at the other person, the other person can catch the ball and throw another ball in a different direction. Similarly, if one electron emits a photon, the other electron can absorb the photon and emit a new photon in a different direction.
• The photon that is exchanged in this process is called a virtual photon. Virtual photons are different from ordinary photons because they cannot be directly detected. However, they can still interact with other particles.
  • Whether a virtual photon is real is a matter of debate among physicists. Some believe that virtual photons are simply a mathematical tool used to calculate the interactions of real photons. Other physicists believe that virtual photons are real particles that exist for a very short period of time.
  • Electron-electron interactions mediated by photons are responsible for many of the properties of matter, such as the electrical conductivity of metals, the colour of objects, and the chemical bonds that hold atoms together.
• Here are four examples of the process of electron-electron interaction mediated by photons:

Møller scattering

• Møller scattering is the name given to electron-electron scattering in quantum field theory. The electron interaction that is idealized in Møller scattering forms the theoretical basis of many familiar phenomena such as the repulsion of electrons in the helium atom.
  • Møller scattering is a fundamental process in physics that describes the interaction between two charged particles. It is mediated by the exchange of virtual photons.
  • When two electrons interact with each other through the exchange of a virtual photon, the photon is emitted by one electron and absorbed by the other electron.
  • This exchange of energy and momentum causes the electrons to change their direction of motion. This change in direction is what we observe as the electric force.

Photoelectric emission

• Photoelectric emission is the process of an electron being ejected from a metal surface when light hits the surface. This process can be explained by the exchange of a virtual photon between the electron and the photon. For example, photoelectric emission is used in solar cells to convert sunlight into electricity.

Colour of objects

• The colour of an object is determined by the wavelengths of light that are absorbed and reflected by the object. The absorption and reflection of light is caused by the interaction of photons with electrons in the object. For example, a red object appears red because it absorbs blue and green light, and reflects red light.

Electrical conductivity of metals

• The electrical conductivity of a metal is determined by the number of free electrons in the metal. The free electrons in a metal can be accelerated by an electric field, which causes the metal to conduct electricity. For example, copper is a good conductor of electricity because it has a lot of free electrons.