Understanding lighting for physically based rendering i wanted to ask if you know the best books or resources to understand light physics. I have heard that Subrahmanyan Chandrasekhar's book "Radiance Transfer" is very good. Any other books or suggestions will be appreciated
Here you have a full repository with a lot of papers about light transport. There's also a folder named 'theory' where you can get both intro and advanced refs regard light physics. And much more. I'm personally curating this and keeping up to date with latest advancements. 

https://drive.google.com/drive/folders/16A6Yj2esRTk0FP-ALr6XfxkGQvTb_1dD?usp=sharing

However here are the main books/papers I suggest to read :

1985 - Physically Based Lighting Calculations For Computer Graphics

1986 - The Rendering Equation

1997 - A Framework for Realistic Image Synthesis

1997 - Robust MonteCarlo Methods For Light Transport Simulation

2011 - The State of the Art in Interactive Global Illumination

2014 - The Path to Path-Traced Movies