Quantum Electrodynamics (QED) Theory.

`In the last science article, we have understood the concept of Nuclear Energy. In this article, we will understand the concept of “quantum electrodynamics (QED).

Before we proceed to Quantum Electrodynamics, we should know the basic definitions of quantum physics and Electrodynamics.

Quantum Physics:

Quantum physics is the study of matter and energy at its most fundamental level. The basic story of everything around us and including us are elementary particles. 

So in simple terms, quantum physics is the study of everything in the universe. It explains how everything works in the universe. To know more about quantum physics, click here.


It is a branch of physics that deals with the consequences emerging from the interactions of electric currents with magnets, with other currents, or with themselves.

Quantum Electrodynamics (QED):

In simple words, it is a theory which explains how electromagnetic radiation interacts with matter on an atomic level. In other words (physics terms), in particle physics, quantum electrodynamics is the relativistic quantum field theory of electrodynamics. Therefore, In principle, it describes how light and matter associate.

It is the first theory where the full correspondence between quantum mechanics and special relativity is achieved. To know more about relativity, click here. Let us understand the history of quantum electrodynamics.


Paul Dirac has the credit of the first basis of QED during the 1920s. He got the basis by calculating an excitation of a subatomic particle from a higher energy level to low energy level ( Also called spontaneous emission).

As the calculations were not precise due to the advancement in technology, a new theory was the need of that hour. Therefore, In 1948, there came a revolution with the precise and accurate calculations of QED.

Three of the brilliant minds in the ream of physics named Sin-Itiro Tomonaga, Julian Schwinger and Richard P. Feynman got the calculations precisely for QED. They were awarded Nobel Prize Jointly in the year 1965 for ” their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles.”

The most important Physicist of the above realm who not only has a major contribution to QED but also many fields of physics is Richard P. Feynman. Lets us see his view on the same.

Feynman’s view of Quantum Electrodynamics:

The key components of Feynman’s presentation of QED are three basic actions.

  • A photon goes from one place and time to another place and time.
  • An electron goes from one place and time to another place and time.
  • An electron emits or absorbs a photon at a certain place and time.

These were represented by diagrams known as “Feynman diagrams” which revolutionized modern physics forever. 

Feynman Diagrams:

They are pictorial descriptions of the mathematical expressions representing the behaviour and interaction of subatomic particles.

The following image is the Feynman diagram.

Picture Of A Feynman Diagram.

To know more about fermions, photons, gluons, Higgs boson and other concepts of particle physics, click here.

Applications Of Quantum Electrodynamics:

  • In Moessbauer-spectroscopy which is a way to determine the elements in a sample by scattering of gamma radiation.
  • Engineering modern nuclear fission and fusion technologies.
  • In modern optics.
  • Building quantum devices (like quantum computers, quantum chips etc.,)

In conclusion, quantum electrodynamics is very important to understand the functionality of our universe.

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