Restructure: USD fix + updated descendants

# [SCI] Gravitational Wave Astronomy

**Gravitational Wave Astronomy** is the new observational discipline inaugurated by LIGO's first detection (2015), using gravitational waves to observe violent astrophysical events invisible to electromagnetic telescopes.

## Overview

Gravitational waves carry information about the dynamics of their sources — mass, spin, orbital parameters — that electromagnetic radiation cannot provide. In five observing runs (2015–2023), LIGO-Virgo-KAGRA detected 90+ events: binary black hole mergers, neutron star mergers (with electromagnetic counterparts in 2017 — GW170817 — enabling multi-messenger astronomy), and possibly neutron star–black hole mergers. These observations have tested GR in the strong-field regime, constrained the neutron star equation of state, measured the Hubble constant independently, and revealed a population of black holes previously unknown.

## Key Figures & Recognition

- **Kip Thorne** (1940–), **Rainer Weiss** (1932–), **Barry Barish** (1936–): LIGO/gravitational wave detection. **Nobel Prize 2017**.

## Seminal Papers

- [Abbott, B.P. et al. (LIGO/Virgo). "GW150914." *PRL* 116 (2016)](https://doi.org/10.1103/PhysRevLett.116.061102)
- [Abbott, B.P. et al. "Multi-messenger Observations of a Binary Neutron Star Merger." *ApJL* 848 (2017)](https://doi.org/10.3847/2041-8213/aa91c9)

## What This Enables

This is a current frontier node in this graph — no downstream connections yet recorded in this graph.

# Parents

* [TECH] LIGO Gravitational Wave Detector
* [SCI] Gravitational Wave Theory
* [TECH] Rocket & Space Launch
* [TECH] LIGO Gravitational Wave Detector