Modular forms are used to solve Fermat's last theorem, Mock modular forms are used in black holes theory. I read also in Quanta magazine that Eisenstein series are used to compute what we call Monster group. https://d2r55xnwy6nx47.cloudfront.net/uploads/2017/08/symmetry-algebra-and-the-monster-20170817.pdf

Modular forms are used to solve Fermat's last theorem, Mock modular forms are used in black holes theory. I read also in Quanta magazine that Eisenstein series are used to compute what we call Monster group. https://d2r55xnwy6nx47.cloudfront.net/uploads/2017/08/symmetry-algebra-and-the-monster-20170817.pdf Here is an interesting article to see the beautiful application of modular forms in astronomy https://m.facebook.com/story.php?story_fbid=795545447309716&id=247304225467177