FREE ESSAY ON UNIFICATION THEORY

UNIFICATION THEORY

Unification Theory
In particle physics, an attempt to explain all of the fundamental forces and their
relationships between elementary particles in single framework was accomplished in theory
by the g.u.t. by the grand unification theory. In relation to physics these forces can be
described as fields that mediate interactions between separate or distant objects. These
theories such as eltromagnetism and general relativity started to attempt the unification
of theories, however they would emerge as the fundamental basics of the g.u.t. Or the
grand unification theory.
At sub atomic levels, these fields are described as quantum field theories, which started
the ideas of quantum mechanics. In the 1940's the ideas quantum electrodynamics (QED),
the quantum field theory of electromagnetism, became fully developed. In QED, charged
particles interact as they emit and absorb photons (minute packets of electromagnetic
radiation), in effect exchanging the photons in a game of subatomic catch. This theory
has become the prototype for theories of the other forces.
During the 1960s and '70s particle physicists discovered that matter is composed of two
types of basic building block--the fundamental particles known as quarks and leptons. The
quarks are always bound together within larger observable particles, such as protons and
neutrons. They are bound by the short-range strong force, which overwhelms
electromagnetism at sub nuclear distances. The leptons, which include the electron, do
not feel the strong force. However, quarks and leptons both experience a second nuclear
force, the weak force. This force, which is responsible for certain types of
radioactivity classed together as beta decay, is feeble in comparison with
electromagnetism.
At the same time that the picture of quarks and leptons began to crystallize, major
advances led to the possibility of developing a unified theory. Theorists began to invoke
the concept of local gauge invariance, which postulates symmetries of the basic field
equations at each point in space and time. Both electromagnetism and general relativity
already involved such symmetries, but the important step was the discovery that a
gauge-invariant quantum field theory of the weak force had to include an additional
interaction--namely, the electromagnetic interaction. Sheldon Glashow and peers
independently proposed a unified electro weak" theory these forces based on the exchange
of four particles: the photon for electromagnetic interactions, and two charged W
particles and a neutral Z particle for weak interactions.
During the 1970s a similar quantum field theory for the strong force, called quantum
thermodynamics (QCD), was developed. In QCD, quarks interact through the exchange of
particles called gluons. The aim of researchers now is to discover whether the strong
force can be unified with the electro weak force in a grand unified theory (GUT). There
is evidence that the strengths of the different forces vary with energy in such a way
that they converge at high energies. However, the energies involved are extremely high,
more than a million times as great as the energy scale of electro weak unification, which
has already been verified by many experiments.
Grand unified theories describe the interactions of quarks and leptons within the same
theoretical structure. This gives rise to the possibility that quarks can decay to
leptons and specifically that the proton can decay. Early attempts at a GUT predicted
that the proton's lifetime must be in the region of 1032 years. This prediction has been
tested in experiments that monitor large amounts of matter containing on the order of
1032 protons, but there is no evidence that protons decay. If they do in fact decay, they
must do so with a lifetime greater than that predicted by the simplest GUTs. There is
also evidence to suggest that the strengths of the forces do not converge exactly unless
new effects come into play at higher energies. One such effect could be a new symmetry
called supersymetry, which is part of the g.u.t.
Bibliography
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