The "Gun That Can Kill The Past" is a fictional concept from the short story "The Gun" by James L. Sutter. In this narrative, the gun allows its user to erase specific memories or events from their past, effectively altering their personal history. This idea raises questions about the nature of memory and the consequences of changing one's experiences. The story explores themes of regret, identity, and the impact of the past on the present. By using the gun, characters confront their choices and the emotional weight of their memories, ultimately reflecting on the importance of accepting one's history rather than trying to escape it.