Gravitational wave

Visualization of warped space and time around colliding black holes.

A gravitational wave is a ripple in the fabric of spacetime that is generated by certain movements of mass, particularly by massive objects accelerating through space. These waves were first predicted by Albert Einstein in 1916 as a consequence of his general theory of relativity. Gravitational waves transport energy as gravitational radiation and travel at the speed of light.

Properties

Gravitational waves are transverse waves, meaning that the oscillations occur perpendicular to the direction of wave propagation. They are characterized by two polarization states: the "plus" and "cross" polarizations.

Plus polarization of a gravitational wave.

Cross polarization of a gravitational wave.

Plus and Cross Polarizations

The "plus" polarization causes objects to stretch and squeeze along two perpendicular axes, while the "cross" polarization does the same but rotated by 45 degrees. These effects are extremely small, making gravitational waves difficult to detect.

Sources

Gravitational waves are produced by certain movements of mass, particularly by massive objects accelerating through space. The most significant sources include:

• Binary star systems, especially those involving neutron stars or black holes.
• Supernovae, which are massive stellar explosions.
• The early universe, which produced a background of gravitational waves.

Artist’s impression of merging neutron stars, a source of gravitational waves.

Detection

Detecting gravitational waves requires extremely sensitive instruments due to their minuscule effects on matter. The most notable detectors are the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo interferometer. These observatories use laser interferometry to measure the tiny changes in distance caused by passing gravitational waves.

The gravitational wave spectrum, sources, and detectors.

History

The concept of gravitational waves was first introduced by Albert Einstein in 1916. However, it was not until 2015 that the first direct detection of gravitational waves was made by LIGO, confirming Einstein's prediction and opening a new era of astronomy.

The history of the universe, showing the role of gravitational waves.

Applications

Gravitational wave astronomy provides a new way to observe the universe, offering insights into phenomena that are invisible in electromagnetic radiation. It allows scientists to study the properties of black holes, neutron stars, and the early universe.

Related pages

• General relativity
• Black hole
• Neutron star
• LIGO
• Virgo interferometer