In this age of rapid technological advancement, climate change, and resource depletion, it's more important than ever to dive into literary works of science fiction that show the various directions that humanity’s future might take. Unlike other speculative stories, hard sci-fi is driven by biology, physics, mathematics, and engineering, yet it remembers that the most important thing of all is humanity. The best hard sci-fi books of all time go beyond speculating about the future and humanity’s place in the cosmos. They aim to challenge the reader’s understanding of the universe by exploring subjects like interstellar travel, alien ecosystems, and…