#Fact4 (SPACE AND TIME)

• In the real time space time of classical general relativity time is distinguished from the space directions because it increases only along the history of an observer unlike the space directions, which can increase or decrease along that history. The imaginary time direction of quantum theory, on the other hand, is like another space direction, so can increase or decrease.

• In an imaginary space time that is a sphere, the imaginary time direction could represent the distance from the South Pole. As one moves north, the circles of latitude at constant distances from the South Pole become bigger corresponding to the universe expanding with imaginary time. The universe would reach maximum size at the equator and then contract again with increasing imaginary time to a single point at the North Pole. Even though the universe would have zero size at the poles, these points would not be singularities, just as the North and South Poles on the Earth's surface are perfectly regular points. This suggests that the origin of the universe in imaginary time can be a regular point in space time. 

• Instead of degrees of latitude, the imaginary time direction in a space time that is a sphere could also correspond to degrees of longitude. Because all the lines of longitude meet at the North and South Poles, time is standing still at the poles; an increase of imaginary time leaves one on the same spot, just as going west on the North Pole of the Earth still leaves one on the North Pole.