Thi s int roduc tion to Gro up The ory, wit h its emp hasis on Lie Gro ups and the ir app licat ion to the stu dy of sym metri es of the fun damen tal con stitu ents of mat ter, has its ori gin in a one -seme ster cou rse tha t I tau ght at Yal e Uni versi ty for mor e tha n ten yea rs. The cou rse was dev elope d for Sen iors, and adv anced Jun iors, maj oring in the Phy sical Sci ences .