Title Page What is Grand Unified Theory?

Title Page

What is Grand Unified Theory?

• Unified field theory is an attempt to describe all fundamental forces and the relationships between elementary particles in terms of a single theoretical framework.

Current Fundamental Forces

• Electromagnetic

• Weak

• Strong

• Gravity

The Road to Unification

The History of Grand Unified Theory

Electricity and Magnetism

• Michael Faraday:

• Born: September 22, 1791

• Died: August 25, 1867

• English physicist and

• chemist whose many experiments

• contributed greatly to the understanding of electromagnetism.

Electricity and Magnetism

• James Maxwell

• Born June 13, 1831, Edinburgh, Scotland died November 5, 1879, Cambridge, Cambridgeshire, England

• Scottish physicist best known for his formulation of electromagnetic theory.

• Incorporated light and wave phenomena into electromagnetism

Electricity and Magnetism

• In 1905 Einstein’s special theory of relativity showed that electricity and magnetism were link and that Maxwell was correct.

• The single force of Electromagnetism is born.

Electroweak Force

• Sheldon Glashow

• Abdus Salam

• Steven Weinberg

• Each physicist independently found that the weak nuclear force could be unified with electromagnetic force.

Electroweak Force

• At extremely high energies, 1015 GeV the electromagnetic and weak forces become the same.

• The relationship is based on the exchange of four particles: the photon of EM interactions, two charged W particles and a neutral Z particle.

Electroweak Force

Strong Nuclear Force

• Quantum Chromodynamics was developed to explain strong force during the 1970s.

• Quarks are believed interact by exchanging gluons.

• The hope is to use that similarity to unify strong with electroweak force.

• The unification cannot be found because energy levels 1012 higher than those needed to develop the electroweak force are required to test further unification.

Strong Nuclear Force

Gravity

• Newton showed that both

• astronomical and terrestrial motion could be explained with gravitation

• In 1915 Einstein’s theory of general relativity was written.

• Einstein spent 30 years trying to unify EM with gravity and failed.

The Future of the Grand Unified Theories

Future

• Gravity may be unified by superstring theory, which is the best theory right now for unification.

• Higher energy experiments are needed to study the strong force and its unification with electroweak.

• More study of electroweak is still needed. By using the simplest version of the theory a calculation was performed that determined a proton life several orders of magnitude too short, from 1029 to 1031 years.

• Experiments show that the life of a proton is greater than 1032 years.

References

• "Electromagnetism." Encyclopædia Britannica. 2004. Online. Retrieved 10 May 2004
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• "Electroweak Theory." Encyclopædia Britannica. 2004. Online. Retrieved 10 May 2004

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• “Forces.” Bring, Lars. Nobel e Museum. Online. Retrieved on 7 May 2004 from

• “Grand Unified Theory.” CERN. Online. Retrieved on 8 May 2004 from

• “G.U.T.” York University. Online. Retrieved on 7 May 2004 from

• Modern Physics for Scientists and Engineers, 2nd Edition. Thornton. Saunders

• College Publishing. 2000. Pg. 13, 494-496.

• "Unified Field Theory." Encyclopædia Britannica. 2004. Retrieved 10 May 2004 from

• .

• “Unified Field Theory.” University of Oregon. Online. Retrieved on 10 May 2004 from