What actual problems of physics are not solved at the moment?

Question

Physics

What actual problems of physics are not solved at the moment? What paradoxical phenomena (preferably at the corpuscular and atomic levels, but molecular ones are also suitable) does she know?
These must be phenomena confirmed by experiment, or described on the basis of experiment.

Answer 1

Unsolved problems of modern physics

Answer 2

Here is an interesting article by V. L. Ginzburg, albeit fifteen years ago.

Answer 3

quantum entanglement