There has never been anything behind your field of awareness. In other words, your point of view(POV) is always looking forward. Philosophers and movie makers deem this POV as the ‘fourth wall’. Imagine that you were making a movie or a TV show. The set would have three walls to enclose the boundary of the scene, and the camera, along with boom and mic, would be the proverbial fourth wall. We have all seen poorly produced movies where the camera or mic are in the shot. Once the guts of the production are noticed, the suspension of disbelief is ruined.