# null infinity

> English word · Noun

## Definitions
1. In a closed space-time, especially for an Einstein cylinder, null infinity for a given point is the limit of convergence of the light cone most distant from the given point. That is, it is the limit of a set of points that each have a time-like separation from every point that has a space-like separation from the given point.

## Etymology
From the physics concept of "at infinity" or "far", where fields are small, and the math concept of null set. Ironically, a null infinity may be neither far nor a null set.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/null-infinity