A world that floats like a leaf

It's a strange thing that fantasy world-builders will happily allow for biology that defies reason, but when it comes to the shape of the world they stay shackled to the globe.  Suppose that there is a world that isn't a sphere.  Suppose that it has a different shape, but that the logic of that shape still gave its creatures a day to day experience that is easily imagined.  Where would imagining such a world take us?

According to surviving fragments, the ancient Greek philosopher Anaximanes believed that the earth was flat and floated like a leaf.  Now, flat earths are not uncommon, but usually a flat earth rests upon something.  (For some reason, turtles often draw the short straw.)  A leaf-like world, floating through the infinite air that Anaximanes held to be the most fundamental type of matter has very interesting implications.

My mind goes to the seasons first.  How do these come to pass?  Axial tilt is not promising!  Different gusts in the infinite air could put off an explanation until one looks at the greater sphere of existence - "what causes those currents?"  But suppose that the sun is a great ball of fire trapped in a tube affixed to the western and eastern poles.  If the tube was firmly fastened, the path of the sun would be neatly over the equator and there would be variation by latitude but not by season.  But suppose that it can swing more or less freely, with just a greater weight to the part of the tube beneath the earth to keep the system stable.  Then note that this world floats relatively low in the infinite air - this must be so, because its inhabitants can look up to see the bottom of other leaf-worlds at night, with those distant appearing similar to the stars we see and the closest being similar to our moon.  This means that the solar tube runs close to the eternal ice that rests at the very base of existence.  The passing of the sun each night causes ice to become steam, propelling the solar tube upwards and moving the perceived orbit of the sun towards southern latitudes.

5 minutes in GIMP.  Hopefully it gets the idea across.

 

The propulsion from steam would fall away as the solar tube receded from the ice, then start up again when the tube drew close again.  Suppose that the equilibrium achieved is the motion of a pendulum, and the leaf-world will have seasons of a familiar kind through most latitudes - though the four poles of the world will be very strange indeed.

But before that equilibrium is achieved, the motion might be very slow and seasons could last for centuries.  Suppose that in the long winters, creatures with a greater affinity to ice and solids emerged, such as the Dwarfs.  In the long summers, creatures with a greater affinity to fire and gas came forth, such as ivory-skinned Zanthi.  For the Dwarfs, summers were weathered by going underground.  The Zanthi chased the sun whenever their summers began to fade.  Those creatures belong to the Old Times, and mainly dwell at the poles most comfortable to them.  In Modern Times creatures of fluidity and change came forth, the most successful of which is the human race.  They were joined by the Gorpo.  These creatures of the Moon came down from that high-floating world when the infinite air above grew thin.  Sages from all of these peoples worry that the air will grow thin on earth one day and have proposed various schemes to escape or trap an atmosphere.