# The Gravitational-Wave Physics

## TL;DR

This review discusses the sources and physics of gravitational waves, highlighting their significance for astronomy, cosmology, and fundamental physics, and emphasizing recent detections and future prospects.

## Contribution

It provides a comprehensive overview of gravitational wave sources, their physics, and their applications in cosmology, integrating recent developments and future directions.

## Key findings

- Detection of gravitational waves marks a new era in astronomy.
- Gravitational waves originate from inflation, phase transitions, and binary mergers.
- Gravitational waves serve as standard sirens for cosmological measurements.

## Abstract

The direct detection of gravitational wave by Laser Interferometer Gravitational-Wave Observatory indicates the coming of the era of gravitational-wave astronomy and gravitational-wave cosmology. It is expected that more and more gravitational-wave events will be detected by currently existing and planned gravitational-wave detectors. The gravitational waves open a new window to explore the Universe and various mysteries will be disclosed through the gravitational-wave detection, combined with other cosmological probes. The gravitational-wave physics is not only related to gravitation theory, but also is closely tied to fundamental physics, cosmology and astrophysics. In this review article, three kinds of sources of gravitational waves and relevant physics will be discussed, namely gravitational waves produced during the inflation and preheating phases of the Universe, the gravitational waves produced during the first-order phase transition as the Universe cools down and the gravitational waves from the three phases: inspiral, merger and ringdown of a compact binary system, respectively. We will also discuss the gravitational waves as a standard siren to explore the evolution of the Universe.