Quantum electrodynamics (QED) describes the interaction between matter and light. It was the first theory to show the relationship between quantum mechanics and special relativity. QED was developed in the 1920s-1970s through the work of scientists like Dirac, Fermi, Feynman, Politzer, Coleman, Gross, and Wilczek. Feynman diagrams provide a visual representation of interactions like photons being emitted or absorbed by electrons. QED explains phenomena like annihilation and pair production and is the basis for other theories like quantum chromodynamics.

1. QUANTUM
ELECTRODYNAMICS
(QED)
An intelligent work by
S.Sujith somraaj

2. QUANTUM ELECTRODYNAMICS(QED)
Quantum – Light
Electrodynamics – Interaction between electric charges
and current
It describes how matter and light interacts.
It’s a first proof for relation between quantum
mechanics and special relativity.

3. QUANTUM MECHANICS(QUANTUM PHYSICS)
Quantum physics Classical physics
1.Behaviour of matter and
light at atomic and sub
atomic scale.
Behavior of particles at
macro molecular scale
2.It attempts to describe the
properties of esoteric
properties such as quarks
and gluons.
Its describes the properties
of matter such as energy
,velocity, momentum and
other quantities.
3.There is no precision in
measuring the properties of
sub atomic particles
(Uncertainty Principle).
There is a high precision in
measuring the properties of
macro molecular objects.

4. RELATIVITY
Einstein explained this in two interrelated
concepts,
Special Theory and
General theory.
Special theory General theory
1.The laws of physics are
the same for all observers
in uniform motion with
relation to one another.
Theory of gravitation
proposed by Albert
Einstein. Equivalence of
gravitational mass and
inertial mass.
2.The speed of light is a
constant in all frames of
reference.
It says that the space time
is curved.

5. HISTORY OF QUANTUM ELECTRODYNAMICS
 In 1920s Paul Dirac first described radiation and
matter interaction.
 He directed the creation and annihilation
operators.
 Fermi made it possible to compute the
properties of photons and other sub atomic
particles.
 In Early 1960s & 1970s the structural work by H.
David Politzer, Sidney Coleman, David
Gross and Frank Wilczek gave it a theoritical
background.

6. THE STRANGE THEORY OF LIGHT AND MATTER
Richard Phillips Feynman(May
11, 1918 – February 15, 1988) was
an American theoretical
physicist known for his work in
the path integral
formulation of quantum mechanics,
the theory of quantum
electrodynamics.
Nobel Prize in Physics - 1965

7. According to Feynman,
 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 actions are represented in a form of visual
shorthand by the three basic elements of Feynman
diagrams:
 a wavy line - photon
 a straight line - electron and
 a junction of two straight lines and a wavy one for a
vertex representing emission or absorption of a photon
by an electron.

10. APPLICATIONS OF QUANTUM MECHANICS
1.The Grand Unified Theory
A Grand Unified Theory (GUT) is
a model in particle physics in which at high
energy, the three gauge interactions of
the Standard Model which define
the electromagnetic, weak,
and strong interactions, or forces, are merged
into one single force. If Grand Unification is
realized in nature, there is the possibility of
a grand unification epoch in the early universe in
which the fundamental forces are not yet
distinct.

11. ANNIHILATION, IN PHYSICS,
REACTION IN WHICH A
PARTICLE AND ITS
ANTIPARTICLE COLLIDE AND
DISAPPEAR, RELEASING
ENERGY. THE MOST
COMMON ANNIHILATION ON
EARTH OCCURS BETWEEN
AN ELECTRON AND ITS
ANTIPARTICLE, A POSITRON.
2.Annihilation and pair production can be
explained through QED.

12. 3.QUANTUM CHROMO DYNAMICS
 In theoretical physics, quantum chromo
dynamics (QCD) is the theory of the strong
interaction between quarks and gluons, the
fundamental particles that make up
composite hadrons such as
the proton, neutron and pion. It is generally
developed based on QED.

13. QUARKS

14. GLUONS

15. BIBLIOGRAPHIES AND REFERENCES
 https://en.wikipedia.org/wiki/Quantum_electrody
namics
 http://hyperphysics.phy-
astr.gsu.edu/hbase/Forces/qed.html
 https://en.wikipedia.org/wiki/Quantum_mechanic
s
 https://en.wikipedia.org/wiki/Theory_of_relativity
 http://www.encyclopedia.com/science-and-
technology/physics/physics/quantum-
electrodynamics