OBSERVATION BUBBLE is an imaginary bubble that surrounds us and onto which we seem to project our observations of all objects. We borrow the term bubble from psychology, where it is used to describe our behavior as a result of the presence of other people in our immediate environment. Psychology uses it to describe the difference in our reactions to people inside such a bubble from our reactions to the presence of people outside the bubble.
An ideal OBSERVATION BUBBLE has the surface shape of an ideal sphere. But we can represent it with some accuracy as polyhedrons, which have a surface composed of walls called PLANES OF OBSERVATION. It turned out to be most advantageous to represent the OBSERVATION BUBBLE as a polyhedron whose walls, i.e. the PLANES OF OBSERVATION, form identical equilateral triangles.