>But neither the NN nor the researcher will be able to give you a rule like: "F=(G m_1 m_2)/(r^2)" to explain the underlying reasons for the object-trajectory dynamics.

It is not impossible. There is a combination of a special neural network architecture and strong sparsity-inducing regularization that makes it possible to learn equations from dynamics dataset: https://openreview.net/pdf?id=BkgRp0FYe