OSR: Cosmology & Deep Time

The Deep Time machine keeps on going. Things seem to be moving on to how Deep Time could be used to create worlds with bizarre layouts, as opposed to the regular geological layers in a sphere. Skerples has posted about spiral worlds, where travelling downstream brings you to past epochs and an upstream passage has yet to be discovered (or maybe a cold, icy future is what awaits), which I found to be a very interesting take.

This got me thinking about how Deep Time could be integrated into a setting's cosmology, and how this could affect the shape and layout of the material world. One thing that immediately popped into my head was Yggdrasil in Norse mythology - the enormous tree that connects the nine realms of gods and mortals.

Etrian Odyssey V: Beyond the Myth

Premise

In the beginning the Authority created the First World, forming it from the raw stuff of chaos that roiled and churned in the void. It created and hung the burning sun in the day sky and the moon and stars in the night and sculpted the land and seas in the ways that pleased It, and the First World was good and beautiful. But the Authority was unsatisfied with Its creation for nothing lived and moved below it, and it created plants and animals the likes of which mortals have never seen. The Authority was pleased and It made and planted the Tree of Eternities and made Its throne atop the highest reaches, whereby It could survey Its kingdom. And it was good.

The Tree of Eternities grew beyond all other plants and creatures and the Authority could see all of Its creations in all their wonder. But the Authority had made the Tree of Eternities from Its own power and its branches breached the firmament even as its roots pierced the floor of the First World and entered the void. Thus was chaos and magic unleashed upon the First World, destroying all that the Authority had made good. The Authority left the First World and created Heaven, whereby it could better view all of creation, and created the Second World from the Tree of Eternities and Hell from its roots.

I've thought up a few possibilities as to how this could play out.

Credit, Vincent Presseau

Necklace Worlds

The Tree of Eternities grows upwards like a regular tree. The Authority creates a new world around the upper trunk of the tree. The icy north & south poles of the world abruptly give way to lush greenery and warmth, and an enormous knotted trunk emerges from the ground and stretches into the sky. It can't be seen from far away because the Authority keeps it hidden, but astronomers note the regular and uniform spacing of the planets that they can see through their telescopes. Travellers can ascend up and down the trunk to reach past or future worlds, or Heaven and Hell if they travel far enough. The various worlds are strung together like beads on a necklace of vines. You could travel from one world to another with a spaceship quite easily. Offshoot growths of the Tree of Eternity can provide smaller routes of access to the main trunk.

Matryoshka-Doll Worlds

The Tree of Eternities continues to grow and the Authority creates new worlds inside it. As the tree grows more rings, more worlds are created on top of the last. The worlds are cylinders - one can travel the circumference without difficulty but the upper and lower ends gradually dissolve into oozing channels of divine xylem. As the Tree grows, its cambium produces a new layer that builds off the old, leading to a common history that runs through the many layers. With adequate equipment and preparations one can travel through the Tree's vascular system and be deposited on other worlds. The other way to do this is to dig deep enough or climb high enough to find the tough sapwood layers that separate the rings and break through to the next world (this has a high fatality rate due to sudden exposure to great heights or high-pressure magma). If one travels to the heartwood of the tree they have a direct route to the First World and Hell.

Dew-Drop Worlds

As the Tree of Eternities grows, its branches spread and the Authority creates new worlds from them, as drops of dew on a leaf. Each world exists in its own astral bubble, as if suspended in a crystal sphere. Some worlds are created in higher reaches than others and receive more light, and some are created near other things that live on the Tree, like parasites or astral lichen. The Authority moves and reorganises them as it sees fit, which often changes their conditions massively. Worlds on the same branch tend to be more similar than those on different branches. One can travel between worlds by breaching the surface of a celestial sphere and undertaking a long and hazardous journey on the surface of the Tree of Eternities, which still exists in the corrupted First World.

Fractal Worlds

The branches of the Tree of Eternity pierce the firmament at different angles as they grow towards the light of Heaven. As they grow and branch, the Authority creates new worlds upon them, and new worlds from these when they too branch. Each branch is associated with the end of an epoch, and the worlds created from the branch can diverge wildly. Most of the worlds look like shelf fungi growing out from the branches and vary wildly in overall shape. Their one common factor is that one of the cardinal directions inevitably ends in an enormous, curved wall of bark. Bold explorers can traverse the branches and find other worlds that mirror their own, or travel back to the main trunk and experience ancient epochs.

Coppice Worlds

The Tree of Eternities breaches the firmament and a new world is formed around it. However, the Authority, ever wary of further cosmological problems, regularly coppices the Tree back down to the level of the First World. This completely destroys the world currently built around the Tree, but broken traces of it remain in the lower reaches of the new world that is formed as the Tree rapidly regrows. The deeper one travels, the closer to the First World and Hell they get. Stories of judgement, wrath and revelation have a real chance of coming true if pruning time is getting close.