Explore the fascinating intersection of quantum physics, string theory, and black holes in this comprehensive lecture by Professor Atish Dabholkar from ICTP. Delve into the intricate connections between quantum black holes and topics in number theory and geometry. Begin with fundamental concepts and motivations from physics, gradually building up to more complex ideas. Gain insights into quantum field theory and string theory through carefully chosen examples. Discover the basics of harmonic oscillators, quantum mechanics, and the Eisenberg Principle. Examine physical systems, time evolution, and measurement in the context of quantum mechanics. Ideal for mathematicians and students from various physics backgrounds, this lecture requires only a basic understanding of undergraduate physics. Learn about the upcoming book "Quantum Black Holes and Modular Forms" which expands on these concepts.