# Spacetime

Mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold.

- Spacetime500 related topics

## Theory of relativity

The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively.

It introduced concepts including 4-dimensional spacetime as a unified entity of space and time, relativity of simultaneity, kinematic and gravitational time dilation, and length contraction.

## Lorentz transformation

In physics, the Lorentz transformations are a six-parameter family of linear transformations from a coordinate frame in spacetime to another frame that moves at a constant velocity relative to the former.

## Dimension

[[File:Dimension levels.svg|thumb | 236px | The first four spatial dimensions, represented in a two-dimensional picture. 1. Two points can be connected to create a line segment.

The four dimensions (4D) of spacetime consist of events that are not absolutely defined spatially and temporally, but rather are known relative to the motion of an observer.

## Time

Continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future.

The physical nature of time is addressed by general relativity with respect to events in spacetime.

## Minkowski space

In mathematical physics, Minkowski space (or Minkowski spacetime) is a combination of three-dimensional Euclidean space and time into a four-dimensional manifold where the spacetime interval between any two events is independent of the inertial frame of reference in which they are recorded.

## Special relativity

1) The laws of physics are invariant (that is, identical) in all inertial frames of reference (that is, frames of reference with no acceleration).

Rather than an invariant time interval between two events, there is an invariant spacetime interval.

## General relativity

Geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics.

General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime.

## Manifold

Topological space that locally resembles Euclidean space near each point.

Symplectic manifolds serve as the phase spaces in the Hamiltonian formalism of classical mechanics, while four-dimensional Lorentzian manifolds model spacetime in general relativity.

## Physics

Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.

## Motion

Phenomenon in which an object changes its position with respect to time.

Motion applies to various physical systems: objects, bodies, matter particles, matter fields, radiation, radiation fields, radiation particles, curvature, and space-time.