Universe

## The Universe

The Universe is consist of all of space and time and their constructs, including planets, stars, galaxies, all forms of matter and energy. Due to the Unkown spatial size of the universe, we use the observable universe as a baseline universal feat. The observable universe is currently estimated to be 93 billion light-years in diameter. In certain cosmologies, there can be many universes (usually causally disconnected) that form a greater whole called a multiverse, Which similarly comprises all of space and time and its contents; as a consequence, "The Universe" and "multiverse" are often synonymous terms in such settings.

## Universe Size Realms

It's common in fictional realities to be scale based on creating one or multiple "Worlds", "Dimensions", or "Realms". However, many people may often be confused on whether those are synonyms of universes or simply pocket realities. For it to be considered a Universe Size realm, please take the following notes:

* If they are outright stated to be the size of universes by a reliable source, they should be considered universes.
* If the size of the realms described has having infinite sizes or other synonyms, that should strongly indicate them being universes.
* If they're flat out stated to be entire timelines, then they are indeed alternate universes.
* Being labeled as "Entire Alternate Realities" generally indicates them being called universes, but the context and semantics should preferably be specified.

## Regarding Seperation of Universes

travel between universes is not feasible unless through the use of a portal or similar unusual mechanisms. This is because it should be impossible for two distinct universes to be connected by a path that only goes through regular 3 dimensional space. Universes must be separated by something other than 3 dimensional distance or physical barriers, otherwise they would be considered to both be part of one large universe for our tiering purposes.

## The Space-Time Continuum

The spacetime continuum is a fundamental concept in physics that combines the three dimensions of space with the dimension of time into a unified framework. It is a mathematical model used to describe the fabric of the universe, where both space and time are interconnected and affected by the presence of mass and energy. In this model, the fabric of spacetime is not static but can be curved or warped by the presence of massive objects, such as stars or black holes. To understand the spacetime continuum, let's break down its key components. First, we have space, which is the three-dimensional realm in which objects and events exist. Space is typically described using Cartesian coordinates, where each point is specified by its distance from a reference point in three orthogonal directions: x, y, and z.

On the other hand, time is the dimension that allows events to occur and change to happen. It is often represented as the fourth dimension in the spacetime continuum. Time is typically measured in seconds, minutes, hours, and so on, and it provides a framework for ordering events and determining the duration between them. The idea of the spacetime continuum arises from the theory of general relativity, proposed by Albert Einstein in 1915. According to this theory, the presence of mass and energy warps or curves the fabric of spacetime. This curvature affects the motion of objects and the propagation of light, leading to the phenomena of gravity.

The curvature of spacetime can be visualized by imagining a massive object placed on a rubber sheet. The object creates a depression in the sheet, causing nearby objects to roll towards it. Similarly, a massive object curves the fabric of spacetime, causing other objects to move along curved paths in its presence. This effect is what we perceive as gravity. The spacetime continuum also incorporates the concept of the speed of light, which plays a crucial role in Einstein's theory. According to special relativity, also formulated by Einstein, the speed of light in a vacuum is constant and represents an upper limit for the propagation of information. This constant speed of light forms a fundamental constraint on how objects and events can interact with each other within the fabric of spacetime.

The spacetime continuum is not just a passive stage on which events unfold. It is a dynamic and interactive medium that influences the behavior of objects and the flow of time itself. Massive objects create gravitational fields that bend the paths of other objects, and this bending affects the perception of time as well. Clocks in stronger gravitational fields tick more slowly compared to clocks in weaker fields—an effect known as time dilation. Moreover, the spacetime continuum is not limited to our everyday experience of three spatial dimensions and one temporal dimension. The mathematical framework of general relativity allows for the existence of additional spatial dimensions, beyond the familiar up-down, left-right, and forward-backward directions. These extra dimensions, if they exist, would be tightly curled up or compactified and would be beyond our direct perception.

### **Qualifications**

In order for something to qualify as a proper space-time continuum in regard to some feat usually one of two following two criteria should be met:

1. It is explicitly stated to be a "Space-time continuum" or something equivalent.
2. It fulfills the standards for being a universe-sized realm and all of its time is also involved in its feat.