Beidou Echo

"Beidou Echo" --- It took him eight years to build a machine. Not to change the world, but to return to Ward 303 of Hualin First People's Hospital. Back to that afternoon, before my father died. A team of more than a dozen people, four levels of physics, 3,000 people working day and night. Just for seven seconds. Seven seconds was enough for him to finish that sentence: "Dad, your son is not useless. He is finished." The father reached out and touched his face, feeling the real warmth. "I know. I always knew." This is a meeting exchanged for the laws of the universe. The end point is not to change the past, but to let a person see with his own eyes—— Those he didn't have time to see. I have walked a long way since you left. I just want to come back and tell you that I am fine.