Paper space is a series of 2D+1T universes, collectively known as flatland. 127 years since the victorian era, it has been evolved from a closed, self satisfied society to a open and busy metropolis. The breakthrough in interdimensional travel in the 30th century allows the inhabitants to discover other paper spaces and eventually gain a visit to higher dimensional universes. In the meantime, humans and other higher dimensional beings can travel to and from paper space via special gateways to gain a unique experience in lower dimensional space.
5b yrs ago: Formation of paper space by intersection of two branes
1b yrs ago: Formation of the first stars
0.32b yrs ago: formation of the first galaxies
1.2m yrs ago: Origin of the first 2D life
0.2m ago: Origin of the first paperians
1884: The square's visit to 3D space, and the later imprisonment by the leaders of flatland
1885: The freedom revolution, and the start of the First Paper War
1901: Evolution of paperians into complex shapes
1969: End of the First Paper War and the awareness of the existence of 3D space
2011: Overthrowing of imperialism
2455: Completion of the first 2D to 3D gateway
2903: Completion of the two way 2D to 3D gateway
3109: Completion of the first interdimensional drive
Geometry and structure
Most paper space are huge flat planes of about 101000 lyrs x 101000 lyrs in area. Some are non Euclidean space which are ellipsoid, hyperbolic or twisted. They have zero thickness.
Gravity is two times stronger than in the Standard universe. In some, a weaker background gravity acting on the plane by external dense objects exists in addition to the local gravity, creating a 2D space where downwards is defined universally.
Energy disperse according to inverse law instead of inverse square law.