Design of life

I was writing some trailer notes for my trailer editor and was talking about nostalgia, childhood, longing etc that is the core theme of time machine and somewhere I wondered why was life designed like this where time was unidirectional and ephemeral? Why couldn't we visit childhood or youth the way we can visit different places in the world?

Anyways I ended up writing a story in this hypothetical world where one day the doorbell rings and we find that the older version of the family's son has come to visit the family. Initially there is super excitement- there are gifts and souvenirs and the older version is welcomes and he decides to stay on for a few days. However, gradually the family and even the son starts getting annoyed by the presence of this old intruder and start missing his privacy. The whole family keeps waiting and wondering when this old man will leave but feels it won't be right to enquire from him. They try to check his return tickets and worry when they don't find any.