Proof of the Past

When two worlds merge. Scientific theories that were once abandoned by mankind have become mainstream. The earth is endless and flat. The center of the universe lies beneath your feet. Space that we cannot see or touch is filled with a medium called ether. Phlogiston is everywhere and included in everything. Living things are alive because they contain phlogiston; inanimate objects can burn because they contain phlogiston. … Yet all science is not static. Just like light. Different observation conditions can produce different observation results. The survivors from the earth are at odds with the empire. They want to "set things right" and establish the earth's scientific system. How to make the flat and endless land into a round shape? Please give proof! ———— PS: This is a book suitable for reading slowly.