Twentieth Arnold Sommerfeld Lecture Series, Global symmetries and gauge symmetries have played a crucial role in physics. The

idea of duality demonstrates that gauge symmetries can be emergent and might not

be fundamental. During the past decades it became clear that the circle of ideas

about emergent gauge symmetries and duality is central in different branches of

physics including Condensed Matter Physics, Quantum Field Theory, and Quantum

Gravity. We will review these developments, which highlight the unity of physics.