# Gravitational waves

**Gravitational waves** are distortions in space travel at the speed of light away from a mass that moves. Predicted by Albert Einstein's Theory of Relativity in 1916, and at one time the subject of a hoax^{[1]}, gravitational waves have never been observed until 2015, when the first evidence of their existence was confirmed^{[2]}.

## Description

Gravitational waves are essentially "ripples", similar to the ripples made in a pond when a pebble is tossed in, but on a cosmological scale. The mass in question are binary systems - pulsars, neutron stars, or black holes - which orbit around each other. According to Einstein's General Theory of Relativity and his formula E=mc^{2}, both objects emit gravitational waves while losing energy as they gradually approach, eventually resulting in a collision at one-half the speed of light, forming a single object as well as emitting a final, very strong burst of gravitational waves

As part of his relativity theory, Einstein came up with his "quadrupole formula", which describes the rate of wave emmissions from a system of astronomical masses based on the change of the mass itself, what he called the "quadrupole moment". His formula as originally postulated was

- gravitational wave, and mass quadrupole moment.

The results of his findings were published in 1916 as *Näherungsweise Integration der Feldgleichungen der Gravitation* (*"Approximate Integration of the Field Equations of Gravitation"*), but serious errors led him to a revision, published in 1918 as *Über Gravitationswellen* (*"About Gravitational Waves"*).

## See also

## References

- ↑ http://discovermagazine.com/2014/april/23-20-things-you-didnt-know-about-hoaxes
- ↑ http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.116.061102

- Einstein, Albert. "Näherungsweise Integration der Feldgleichungen der Gravitation";
*Proceedings of the Royal Prussian Academy of Sciences*(1916), Berlin, Germany. - Einstein, Albert. "Über Gravitationswellen";
*Proceedings of the Royal Prussian Academy of Sciences*(1918), Berlin, Germany.