Why Cosmology Is the Backbone of Every Great Universe
Before a single hero swings a sword or a starship leaps to hyperspace, someone had to decide how the universe works. Cosmology — the study of the universe's origin, structure, and ultimate fate — is the invisible scaffolding beneath every compelling fictional world. When done well, it gives readers a sense of weight, consequence, and wonder. When ignored, even the best stories can feel shallow.
This guide walks you through the essential layers of building a fictional cosmology from scratch, whether you're writing a novel, designing a tabletop RPG, or crafting a game world.
Step 1: Define the Origin — How Did Everything Begin?
Every cosmology needs a creation myth or origin event. This doesn't have to be supernatural — it just has to be consistent. Ask yourself:
- Was there a primordial state? (Void, Chaos, a sleeping god, a singular particle)
- What triggered creation? (A divine act, a cosmic accident, a war between forces)
- Who knows this history? (Scholars, priests, ancient races — and do they agree?)
Competing origin myths held by different cultures are a powerful worldbuilding tool. The dwarves may believe the world was carved from a giant's bones; the elves may insist it crystallized from pure thought. Both can be simultaneously "true" within your world's lore.
Step 2: Establish the Physical Laws (or Their Absence)
What rules govern your universe? This is especially critical for science fiction, but fantasy worlds benefit just as much from defined physics — even if those physics include magic.
- Is faster-than-light travel possible? If so, what are the costs?
- Does magic have entropy? Does it drain the caster, the environment, or the world itself?
- Are there multiple dimensions or planes? How permeable are the boundaries?
Consistency is more important than realism. A universe where magic violates thermodynamics is fine — as long as it does so consistently.
Step 3: Map the Planes of Existence
Many of the most iconic fictional universes are multi-layered. Consider structuring your cosmology around distinct planes or realms:
| Plane Type | Function | Example |
|---|---|---|
| Material Plane | The mortal world where most stories take place | Middle-earth, The Forgotten Realms |
| Astral/Ethereal | A liminal realm between worlds | D&D Astral Sea, Warhammer's Warp |
| Divine Realms | Where gods or cosmic forces reside | Asgard, the Seven Heavens |
| Shadow/Death Realm | Where souls go; realm of entropy | The Underdark, the Fade |
Step 4: Design the Cosmic Hierarchy
Who — or what — holds power at the top of your cosmology? Options include:
- Active gods who intervene in mortal affairs
- Distant architects who created the world and departed
- Impersonal forces (entropy, the Weave, the Force) with no will of their own
- Elder things — incomprehensible entities older than gods
The relationship between mortals and these powers defines the tone of your world. A cosmos with meddling gods feels very different from one where divinity is silent and cold.
Step 5: Make It Feel Ancient
The most immersive cosmologies feel like they existed long before your story began. Achieve this by:
- Scattering cosmological ruins and relics throughout the world
- Writing fragmented myths that contradict each other
- Implying events your characters can never fully understand
Mystery is a feature, not a bug. You don't need to answer every cosmological question — in fact, leaving some unanswered creates a richer sense of a universe larger than the story itself.
Final Thoughts
A well-crafted cosmology doesn't just serve as background detail — it actively shapes the stakes, the morality, and the wonder of your world. Start with the big questions, define your rules, then let the details emerge organically. The universe you build will feel all the more real for it.