---
title: "Properties and structure"
id: "properties-and-structure"
project: "Interstellar Travel Safety Procedures Publication2"
url: "https://hedronlabs.clickhelp.co/articles/interstellar-travel-safety-procedures-publication2/properties-and-structure"
updated: 2026-10-01T08:39:33Z
---

# Properties and structure

##  Properties and structure
 
The [no-hair theorem](https://en.wikipedia.org/wiki/No-hair_theorem) postulates that, once it achieves a stable condition after formation, a black hole has only three independent physical properties: mass, electric charge, and angular momentum; the black hole is otherwise featureless. If the conjecture is true, any two black holes that share the same values for these properties, or parameters, are indistinguishable from one another. The degree to which the conjecture is true for real black holes under the laws of modern physics is currently an unsolved problem.

These properties are special because they are visible from outside a black hole. For example, a charged black hole repels other like charges just like any other charged object. Similarly, the total mass inside a sphere containing a black hole can be found by using the gravitational analog of [Gauss's law](https://en.wikipedia.org/wiki/Gauss%27s_law) (through the [ADM mass](https://en.wikipedia.org/wiki/ADM_mass)), far away from the black hole. Likewise, the angular momentum (or spin) can be measured from far away using [frame dragging](https://en.wikipedia.org/wiki/Frame_dragging) by the [gravitomagnetic field](https://en.wikipedia.org/wiki/Gravitomagnetism), through for example the [Lense–Thirring effect](https://en.wikipedia.org/wiki/Lense%E2%80%93Thirring_precession).