People seem to link time to geographical distance. People seem to have a subjective perception of distance in relation to effort over time. The perception of distance between Trondheim and Wienna going by car might be different from the perception of distance between the two same cities going by plane. Also, if the effort involved in traveling from point A to point B is different than the effort involved in going from B to A, the distance between the two points can be perceived as asymmetrical. This means that a reference to distance in the text of a document might be distorted if the distance is an estimate based on a persons perception of a given space.