“We can now hear the universe,” LIGO physicist and spokesperson Gabriela Gonzalez, explains in an enthralling statement about mankind’s latest discovery. She further states, “The field of gravitational astronomy is now a reality due to the detection of gravitational waves”.

Our place in the universe has changed profoundly and this discovery’s impact could be as transformative as the discovery of radio waves or the realization that the universe is expanding. Albert Einstein had proposed the existence of space time ripples about 100 years ago in his theory of general relativity. Gravitational waves are generated by the acceleration (or deceleration) of massive objects in the cosmos. There’s convincing indirect evidence that gravitational waves exist, but a direct detection had proven elusive, until now. We can now sample the space-time ripples generated by some of the most energetic events that occur in the universe and, perhaps, use gravitational waves to reveal new physics and discover new astrophysical phenomena

The gravitational waves carry information about their origin and the nature of gravity. In September 2015, LIGO (Laser Interferometer Gravitational-wave Observatory) discovered the gravitational waves from the merger of two black holes to produce a single, more massive spinning black hole during their final fractional second before the merger. LIGO is located in Livingston, Louisiana, and Hanford, Washington, USA. Their announcement was made public only in February, this year. The scientists at LIGO estimated that the black holes involved in the discovery were 29 and 36 times the mass of the sun and that the event of their merger had taken place some 1.3 billion years ago! This means that it might be possible to listen to the Big Bang that gave birth to our universe!

The Theory of General Relativity states that a binary system (pair of two) of black holes loses energy through the emission of gravitational waves while orbiting around each other. This causes them to gradually approach each other over a span of billions of years and in the final minutes before their merger their speed of approach increases to almost one-half the speed of light. This causes them to form a single massive black hole while a portion of mass of this new black hole is converted to energy (E=mc2) and released as a burst of gravitational waves. Joseph Taylor and Russell Hulse in 1974 discovered a similar binary system composed of a pulsar in orbit around a neutron star. Husle and Taylor were awarded the Nobel Prize for the discovery of the pulsar and demonstrating the possibility of measuring gravitational waves in 1933.

LIGO’s mission is to open the field of gravitational-wave astrophysics through the direct detection of gravitational waves. LIGO detectors use laser interferometry to measure the distortions in space-time occurring between stationary, hanging masses caused by passing gravitational waves.

LIGO is a national facility for gravitational-wave research, providing opportunities for the broader scientific community to participate in detector development, observations and data analysis. It was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech. The research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector. LIGO is funded by the U.S. National Science Foundation and operated by the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT). LIGO’s advanced detectors also received financial support for their construction from Australia, Germany, and the United Kingdom.

LIGO – Discovery Gravitational Waves