+-- {: .rightHandSide} +-- {: .toc .clickDown tabindex="0"} ###Context### #### Philosophy +-- {: .hide} [[!include philosophy - contents]] =-- #### Physics +--{: .hide} [[!include physicscontents]] =-- #### Mathematics +-- {: .hide} [[!include mathematicscontents]] =-- =-- =-- \tableofcontents ## Idea In [[philosophy]], the *universe* is a realm within which (some conceived part, naively and virtually all, of) reality takes place. In [[physics]], a *universe* is a realm within which [[physics]] may be thought of as taking place. Such universes include: * all of [[spacetime]] and its contents, * the [[observable universe]], the part of the universe that is physically observable by humans In [[mathematics]], a *universe* is a realm within which [[mathematics]] may be thought of as taking place. Such universes include: * In [[set theory]], a [[universe of sets]] such as a [[von Neumann universe]] or a [[Grothendieck universe]]; * In [[type theory]], a [[type universe]]. ## Related concepts * [[relativity]], [[relativistic universe]] * [[multiverse]] category: disambiguation [[!redirects universe]] [[!redirects universes]] [[!redirects universe (mathematics)]] [[!redirects universes (mathematics)]] [[!redirects universe (physics)]] [[!redirects universes (physics)]]