combining a CS major with a graduate degree in physics could be a powerful blend, especially for AI development. It would provide a unique interdisciplinary perspective, blending computational skills with a deep understanding of physical principles
Definitely start out with some basic websites that give some free courses. Codeacademy and freecodingcamp also do Youtube videos, but you will prolly need a book to help understand the technical side too. Archive.org does share some good books that many go for.