Some Problems on the Classical N-Body Problem compiled by Albouy, Cabral, Santos

Some Open Problems in geometric control and subRiemannian geometry compiled by Agrachev.

Numerical Semigroups Problem List compiled by Delgado, Garcia-Sanchez, and Rosales

My book with Cambridge (to appear 2025?) describes Four Open Questions in the N-body Problem.

Is Entropy Effectively Computable? Milnor.



for ambitious generalists:
all over math

In physics (dominated by QFT and high energy)