In this talk we will discuss some of the impact of Subramanian Chandrasekhar's work on modern applied mathematics. One of the 
 highlight of the talk will be a discussion of Chandrasekhar's radiative transfer theory where he developed a number of breathtaking mathematical 
 structures such as nonlinear integral equations for the Chandrasekhar H functions and X, Y functions as well as infinite dimensional Riccati (inte
 -gro-partial differential differential ) equations for the scattering matrix long before the infinite dimensional systems theory.