Rymdväktaren ("The Space Guardian") and Nyaga, a duology by late Swedish author Peter Nilson. He was a prominent doctor of astronomy at the University of Uppsala, and a board member of the International Astronomical Union. But he also released many works of poetry.

The books are pretty fantastical and have a lot of speculative ideas but you can tell they are grounded in a solid understanding of physics and cosmology, with a big chunk of interesting philosophy thrown in. A lot of mind boggling stuff happens. For example the protagonists try to build a quantum computer that simulates the universe and end up creating an actual universe, which causes some weird effects on physical constants of our universe.

The main theme is how information is encoded in physical events and whether it can be preserved past the end of our universe. It's been a long time since I read them but at the time I enjoyed them immensely. Unfortunately no English translation seems to be available.