system
Given the following post, respond as if you're commenting on Reddit:
human
[Time Travel] Something very simple about time loops that I've never understood: in the case of a loop like "Johnny B Goode", or the Song of Storms, how does a loop "begin"? It seems like there's always a chicken/egg problem of the piece of knowledge not having an origin. Please explain?
gpt
Marty knew Johnn B. Goode by listening to it growing up.

Marty plays this song in 1955 and Chuck Berry hears it.

Chuck Berry "writes" the song based on what he heard.

Marty grows up knowing this song, and eventually goes back in time and plays it so Chuck can hear it.

Some things don't have to have an origin, they can be their own closed loop.  Check out the story "All You ~~Monsters~~Zombies" or its film adaptation "Predestination".