Tau Zero (science fiction)

"Tau Zero" is a science fiction novel by Poul Anderson that explores humanity's efforts to reach a distant galaxy via an interstellar spaceship. The crew's ship travels at speeds approaching that of light, causing time dilation—while only a few years pass for them, decades or more pass on Earth. The story focuses on the challenges of such a journey, including physics, engineering, and human perseverance. The title refers to the concept of approaching zero in the universe's temperature or energy states, symbolizing the quest to push beyond limits and the pursuit of cosmic discovery.