# nLab timelike curve

Contents

### Context

#### Differential geometry

synthetic differential geometry

Introductions

from point-set topology to differentiable manifolds

Differentials

V-manifolds

smooth space

Tangency

The magic algebraic facts

Theorems

Axiomatics

cohesion

tangent cohesion

differential cohesion

singular cohesion

$\array{ && id &\dashv& id \\ && \vee && \vee \\ &\stackrel{fermionic}{}& \rightrightarrows &\dashv& \rightsquigarrow & \stackrel{bosonic}{} \\ && \bot && \bot \\ &\stackrel{bosonic}{} & \rightsquigarrow &\dashv& \mathrm{R}\!\!\mathrm{h} & \stackrel{rheonomic}{} \\ && \vee && \vee \\ &\stackrel{reduced}{} & \Re &\dashv& \Im & \stackrel{infinitesimal}{} \\ && \bot && \bot \\ &\stackrel{infinitesimal}{}& \Im &\dashv& \& & \stackrel{\text{étale}}{} \\ && \vee && \vee \\ &\stackrel{cohesive}{}& ʃ &\dashv& \flat & \stackrel{discrete}{} \\ && \bot && \bot \\ &\stackrel{discrete}{}& \flat &\dashv& \sharp & \stackrel{continuous}{} \\ && \vee && \vee \\ && \emptyset &\dashv& \ast }$

Models

Lie theory, ∞-Lie theory

differential equations, variational calculus

Chern-Weil theory, ∞-Chern-Weil theory

Cartan geometry (super, higher)

#### Riemannian geometry

Riemannian geometry

## Surveys, textbooks and lecture notes

#### Gravity

gravity, supergravity

# Contents

## Definition

For $(X,g)$ a Lorentzian spacetime, a tangent vector $v \in T_x X$ is called

• timelike if $g(v,v) \lt 0$;

• lightlike if $g(v,v) = 0$;

• spacelike if $g(v,v) \gt 0$.

A curve $\gamma : \mathbb{R} \to X$ is called timelike or lightlike or spacelike if all of its tangent vectors $\dot \gamma$ are, respectively.

Last revised on April 7, 2020 at 07:21:59. See the history of this page for a list of all contributions to it.