"The Door Into Summer"

"The Door Into Summer" by Robert A. Heinlein is a science fiction novel that explores themes of time travel, personal resilience, and entrepreneurship. The story follows Dan Davis, an inventor who devises a revolutionary cooling system. Betrayed and left financially ruined, he dreams of escaping his troubles by moving into the future. Using a form of time travel through cryogenic freezing and future technology, Dan plans to return to a better life. The novel combines technological speculation with a compelling tale of revenge, hope, and innovation, illustrating how determination and ingenuity can help navigate life's challenges and transcend limitations.