Gauge (or Yang-Mills) theories are the building blocks of our current physical understanding of the universe. In parallel, string theory is a framework for a consistent quantum description of gravity. Gauge-String duality a.k.a. the AdS/CFT correspondence is a remarkable connection between these two very different classes of theories. This has, in fact, been one of the main engines driving progress in theoretical physics over the last two decades. I will begin by discussing why it is important to arrive at a first principles understanding of the underlying mechanism of this duality relating quantum field theories and string theories (or other theories of gravity). I will then proceed to discuss a very general approach which aims to relate large N QFTs and string theories, starting from free field theories. This corresponds to a tensionless limit of the dual string theory on AdS spacetime. Finally, I will discuss specific cases of this limit for AdS3/CFT2 and AdS5/CFT4, where one has begun to carry this programme through to fruition, going from the string theory to the field theory and vice versa.
This video was produced by the Chennai Mathematical Institute as part of the workshop Perspectives in Mathematical Sciences.
