Symmetry Principles and Conservation Laws in Atomic and ...

GENERAL ARTICLEBeams of protons were successfully circulated in bothdirections about the LHC in September 2008. Unfortunatelyshortly afterward a fault in one of the 1232superconducting dipole magnets led to signi¯cant damagein one part of the accelerator. Repairs and implementationof additional safeguards has taken just over ayear, leading to colliding beams restarting successfullyin December 2009. In March 2010 a new world recordcollision energy of 7 TeV was achieved. The LHC willrun at this energy until late 2011, before upgrades tothe accelerator will allow collisions at 14 TeV.Within the next fiveyears the LHC willeither confirm theHiggs mechanism orshed light on analternative model ofmass generation.3. ConclusionsThis article (Parts 1 and 2) presents a pedagogical summaryof the importance of symmetry principles in describingmany aspects of physical theories, in particularthose related to atomic, particle and nuclear physics.The continuous symmetries in classical mechanics thatlead to conservation of momentum, angular momentumand other quantities such as the Laplace{Runge{Lenzvector, were the starting point. Then discrete symmetriesP, C and T were discussed, along with how their violationis embedded within the standard model of particlephysics. The particular importance of the combinedoperation of C and P was emphasised as it maps matterinto antimatter. P and T violating phenomena in atomicphysics were discussed as the study of these are at theheart of some of the most exciting current atomic physicsresearch. Finally, spontaneous symmetry breaking andthe search for this phenomenon in particle physics atthe Large Hadron Collider was discussed. We hope thereader is left with a sense of the importance of symmetryand the many areas in which it is signi¯cant.Suggested Reading[1] Details of Lee and Yang’s 1957 Nobel Prize can be found athttp:nobelprize.org/nobel\_prizes/physics/laureates/1957/index.htmlRESONANCE October 2010939