The graph is looking like two strings running together in the flow of time.

…Different vibrations of these strings correspond to different particles, and the theory attempts to unify all fundamental forces, including gravity, with quantum mechanics, requiring extra dimensions beyond the three spatial and one time dimension we experience.”

“String theory is a theoretical framework in physics that proposes the fundamental constituents of the universe are not point-like particles, but tiny, one-dimensional "strings" that vibrate and interact with each other…

I just thought of string theory as a metaphor on the mandolin string in the drawing….