Texas Tech University

Gravitational Waves Detected 100 Years After Einstein’s Prediction

Glenys Young

February 11, 2016

(VIDEO) LIGO opens new window on the universe with observation of gravitational waves from colliding black holes. Seven Texas Tech researchers were involved in the collaborative discovery.

Two Black Holes Merge into One
Two Black Holes Merge into One
(Credit: SXS)

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

Gravitational Waves, As Einstein Predicted
Gravitational Waves, As Einstein Predicted
(Credit: LIGO)

The gravitational waves were detected on September 14, 2015 at 5:51 a.m. EDT by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration, which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy, and the Virgo Collaboration using data from the two LIGO detectors.

Seven Texas Tech University researchers are members of the LIGO Scientific Collaboration: professor Benjamin Owen, assistant professor Alessandra Corsi, postdoctoral researchers Santiago Caride, Robert Coyne, Ra Inta and Nipuni Palliyaguru, all in the Department of Physics; and undergraduate Department of Mechanical Engineering major Chance Norris.

Alessandra Corsi

“For most of human history, everything we learned about the universe outside Earth's atmosphere came through light waves,” Corsi said. “In the last century we started seeing other parts of the electromagnetic spectrum – radio, X-rays and so on, different wavelengths but the same fundamental force of nature.”

Owen added, “Cosmic rays and neutrinos let us see the ‘dark side' of the universe via the second and third fundamental forces. Einstein predicted the fourth fundamental force, gravity, also makes waves that could tell us even more about the dark side of the universe. He thought they would be too faint to detect, but 100 years later we've done it.”

One of the two data analysis algorithms that detected the gravitational waves relied on Owen's work in the last 20 years to efficiently search for signals, and Owen spent three years supervising the stress testing of the other algorithm. Corsi has worked for years at the interface of gravitational-wave physics and astronomy and is one of the key players in the effort to enable sky searches for electromagnetic counterparts to invisible gravitational waves.

Benjamin Owen

Coyne, Palliyaguru and Norris have joined her in this endeavor, which includes searching LIGO data for gravitational waves that leave detectable electromagnetic signatures. Caride and Inta have worked extensively to assure the quality of LIGO data. The Texas Tech group also looks ahead: All members work on searches for long and short gravitational wave signals from neutron stars, which should be detected in the coming years and will carry information not only on gravity but also on matter under the most extreme conditions in the universe.

About LIGO

LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1,000 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. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom and the University of the Balearic Islands in Spain.

Hanford achieves interferometer lock
Hanford achieves interferometer lock
On December 12, 2014, LIGO Hanford achieved its first interferometer "lock."
"Locking" refers to the times during which infrared light resonates throughout the interferometer under computer control.
(Credit: Caltech/MIT/LIGO Lab)

LIGO originally was 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.

Virgo research is carried out by the Virgo Collaboration, consisting of more than 250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.

Gravitational-Wave Observatories Across the Globe
Gravitational-Wave Observatories Across the Globe (Credit: LIGO)

The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed – and the discovery of gravitational waves during its first observation run. The National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project. Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration.

Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin-Milwaukee. Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of the City of New York, and Louisiana State University.

Hanford and Livingston
The LIGO Laboratory operates two detector sites, one near Hanford in eastern Washington (left), and another near Livingston, Louisiana (right). (Credit: Caltech/MIT/LIGO Lab)