Related Experiment Video
Updated: May 2, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Gravitational waves from the sound of a first order phase transition
Mark Hindmarsh1, Stephan J Huber2, Kari Rummukainen3
1Department of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH, United Kingdom and Department of Physics and Helsinki Institute of Physics, University of Helsinki, PL 64, FI-00014, Helsinki, Finland.
Abstract:
We report on the first three-dimensional numerical simulations of first-order phase transitions in the early Universe to include the cosmic fluid as well as the scalar field order parameter. We calculate the gravitational wave (GW) spectrum resulting from the nucleation, expansion, and collision of bubbles of the low-temperature phase, for phase transition strengths and bubble wall velocities covering many cases of interest. We find that the compression waves in the fluid continue to be a source of GWs long after the bubbles have merged, a new effect not taken properly into account in previous modeling of the GW source. For a wide range of models, the main source of the GWs produced by a phase transition is, therefore, the sound the bubbles make.
Related Concept Videos
Sound as Pressure Waves
The pressure fluctuation depends on the difference in displacements between the successive points in the...
Sound Waves
Sound waves are longitudinal in most fluids because fluids cannot sustain any lateral pressure. In solids, however, shear forces help in propagating the disturbance in the lateral direction as well....
Sound Waves: Interference
Phase Transitions
Phase Transitions
Shock Waves
When the source's speed approaches the speed of sound, constructive interference between successive wavefronts emitted by the source occurs immediately behind it. Initially, scientists believed that this constructive interference would result in such high...

