The Warp Refraction Principle

The guitar's fretboard is divided into two separate, but equal, "universes." They both share the same laws of "physics." The lower "universe" is located on strings 6, 5, 4, and 3. The upper "universe" is strings 2 and 1. These "universes" are separated by an anomaly known as "The Warp Refraction Threshold," which is located between the 3rd and 2nd strings. Crossing from one "universe" into the other causes the "optical illusion" that fingerings are offset by one fret.

From Advanced Modern Rock Guitar Improvisation