Gravitational Waves Detected
LIGO scientist David Reitze takes us on a 1.3 billion year journey that begins with the violent merger of two black holes in the distant universe. The event produced gravitational waves, tiny ripples in the fabric of space and time, which LIGO detected on September 14, 2015, as they passed Earth.
Credit: LIGO / SXS Collaboration / R. Hurt and T. Pyle
On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed a transient gravitational wave signal. This event, named GW150914, is the first direct detection of gravitational waves and the first observation of a binary black hole merger. It matches waveforms predicted by general relativity, and these observations demonstrate the existence of binary stellar-mass black hole systems. The LIGO Scientific Collaboration and Virgo Collaboration publicly announced the detection on February 11, 2016. More information about this event is available here.
What are gravitational waves?
What is LIGO?
The Laser Interferometer Gravitational-wave Observatory (LIGO) is made of two detectors situated in the United States, with one in Louisiana and the other in Washington. Each detector is made of two perpendicular arms that are four kilometers in length. Laser beams race down these arms, bounce between mirrors, and interfere with each other back at the source.
What does LIGO measure?
A gravitational wave passing through the detector alters the lengths of the arms (and subsequently, the beams’ path length), and LIGO is able to detect this slight change with unprecedented sensitivity. By comparing the changes in the paths of the laser beams, the detectors are able to detect gravitational waves. More information on LIGO.
Published on: Feb 11, 2016