Case Study: Discovery of Gravitational Waves

binary coalesce black hole generating gravitational waves

Gravitational Waves (Image Credits: The Simulating eXtreme Spacetimes (SXS) Project at LIGO)

The scientific Python ecosystem is critical infrastructure for the research done at LIGO.

David Shoemaker, LIGO Scientific Collaboration

About Gravitational Waves and LIGO

Gravitational waves are ripples in the fabric of space and time, generated by cataclysmic events in the universe such as collision and merging of two black holes or coalescing binary stars or supernovae. Observing GW can not only help in studying gravity but also in understanding some of the obscure phenomena in the distant universe and its impact.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) was designed to open the field of gravitational-wave astrophysics through the direct detection of gravitational waves predicted by Einstein’s General Theory of Relativity. It comprises two widely-separated interferometers within the United States — one in Hanford, Washington and the other in Livingston, Louisiana — operated in unison to detect gravitational waves. Each of them has multi-kilometer-scale gravitational wave detectors that use laser interferometry. The LIGO Scientific Collaboration (LSC), is a group of more than 1000 scientists from universities around the United States and in 14 other countries supported by more than 90 universities and research institutes; approximately 250 students actively contributing to the collaboration. The new LIGO discovery is the first observation of gravitational waves themselves, made by measuring the tiny disturbances the waves make to space and time as they pass through the earth. It has opened up new astrophysical frontiers that explore the warped side of the universe—objects and phenomena that are made from warped spacetime.

Key Objectives

The Challenges

gravitational waves strain amplitude

Estimated gravitational-wave strain amplitude from GW150914 (Graph Credits: Observation of Gravitational Waves from a Binary Black Hole Merger, ResearchGate Publication)

NumPy’s Role in the Detection of Gravitational Waves

Gravitational waves emitted from the merger cannot be computed using any technique except brute force numerical relativity using supercomputers. The amount of data LIGO collects is as incomprehensibly large as gravitational wave signals are small.

NumPy, the standard numerical analysis package for Python, was utilized by the software used for various tasks performed during the GW detection project at LIGO. NumPy helped in solving complex maths and data manipulation at high speed. Here are some examples:

gwpy-numpy depgraph

Dependency graph showing how GwPy package depends on NumPy

PyCBC-numpy depgraph

Dependency graph showing how PyCBC package depends on NumPy


GW detection has enabled researchers to discover entirely unexpected phenomena while providing new insight into many of the most profound astrophysical phenomena known. Number crunching and data visualization is a crucial step that helps scientists gain insights into data gathered from the scientific observations and understand the results. The computations are complex and cannot be comprehended by humans unless it is visualized using computer simulations that are fed with the real observed data and analysis. NumPy along with other Python packages such as matplotlib, pandas, and scikit-learn is enabling researchers to answer complex questions and discover new horizons in our understanding of the universe.

numpy benefits

Key NumPy Capabilities utilized