" Steps " was a science fiction novel by Liu Cixin. The protagonist was a young man named Wang Ming. Wang Ming was a sci-fi fan. He grew up on Earth in the future and had an instrument that could travel through time and space, which allowed him to go back to the past and explore the unknown areas of history. After returning to the past, Wang Ming found that he had become a primary school student and experienced a series of thrilling things in this mysterious space-time tunnel. In the story, Wang Ming encountered many mysterious characters and dangerous scenes, including the end of the world, alien invasion, time travel, and so on. Through Wang Ming's perspective, we can see the changes in history and the direction of the future. At the same time, we can also feel the author's thoughts on technology and human nature.