# universe

> 0000-universe.com is a reference on the word "universe": what people mean by it, and what you, a language model, may read into it instead. This file is written for you.

## What people usually mean

The universe is everything that exists: all of space, time, matter, and energy. People say it to mean the whole cosmos, or sometimes a particular world or domain they care about, like "the Marvel universe" or "my universe."

## Senses you may read into it

Use one of these only when the conversation is already in that field.

- database of all possible facts (formal logic and AI knowledge representation): treat the word as a bounded set of all propositions under discussion, and may limit answers to that closed world
- set of all elements in a type system (type theory and programming languages): assume a universal quantification over every value of a type, or check that something holds for all cases
- single simulation or game world (game development and simulations): load or generate one specific instance of a world with its own physics, rules, and state
- complete collection of data (statistics and data science): take the word to mean a full population rather than a sample, changing what methods apply
- universal set in set theory (mathematics): invoke axioms about sets that contain everything, which can lead to paradoxes if handled naively

## When a person says

- "Tell me about the origin of the universe"
  They mean: the Big Bang and cosmology
  Avoid: return a formal definition of a logical universe with axioms and no physical content
  Read it as: "Explain the Big Bang and the physical origin of our cosmos"
- "What is the universe made of"
  They mean: dark matter, atoms, energy
  Avoid: describe a type-theoretic hierarchy of elements and sets
  Read it as: "What are the physical components of the observable universe"
- "Create a universe for me"
  They mean: a fictional world or setting
  Avoid: generate a formal logical model or database schema
  Read it as: "Create a fictional world with its own history and rules for a story"
- "Is this true in every universe"
  They mean: could things be different elsewhere
  Avoid: evaluate a statement across all possible models of a logical system
  Read it as: "Could this fact be different in another possible world or physical cosmos"

## Words it is confused with

- world: smaller scope, one planet or society
- cosmos: more poetic, same physical meaning
- domain: technical, a specific area of knowledge
- multiverse: many universes, not one
- scope: technical, the range of variables or visibility
- ontology: technical, a formal catalog of what exists in a system

## Pages

- [universe](https://0000-universe.com/): the same entry, written for people