Suggest sci-fi or science books that will break my mind and cause existential dread

I recently read about the idea that the universe has expanded and contracted infinitely in the past and will continue to do so. I love the terrifying feeling of trying to get my head around that. I loved Arthur C. Clarke’s Rama series, read it twice. Alastair Reynolds’s Revelation Space series was good. Basically anything that has weird aliens, covers vast amounts of space and time, makes me question all existence. Sci-fii or nonfiction.