Rainer Weiss (Berlín, 29th September 1932) studied Physics at the Massachusetts Institute of Technology (MIT), where he graduated in 1955 and obtained his PhD in 1962. A professor at Tufts University and a researcher at Princeton, he returned to MIT in 1964 as an associate professor and has developed his entire career there. He has been Professor Emeritus of Physics since 2001. Among his scientific contributions, Rainer Weiss was a pioneer in measuring the radiation spectrum of the cosmic microwave background, radiation originating from photons at the earliest stage of the universe, and also co-founded the Cosmic Background Explorer (COBE) mission, launched in 1989.

He is internationally recognized for inventing the laser interferometric technique, which served as the basis for the construction of LIGO. He laid the groundwork for this project in the early 1970s by detailing how an interferometer should distinguish gravitational waves from background noise. He conducted a thorough analysis of most of the major sources of noise that an interferometer might find and developed a detailed design for a gravitational-wave detector to overcome this noise, which constituted the roadmap for two decades of R&D that eventually led to LIGO.

Member of the US National Academy of Sciences, the American Association for the Advancement of Science, the American Physical Society, the American Academy of Arts and Sciences and the American Astronomical Society, Rainer Weiss formed part of the COBE project team. He was awarded the Gruber Prize in Cosmology in 2006. Among other distinctions, Weiss has received the NASA Achievement Award (1984), the NASA Exceptional Scientific Achievement Award (1991), the Einstein Prize of the American Physical Society (2000) and the Medal of the Association for the International Development of the Nice Observatory (France, 2002).

Kip S. Thorne (Logan, Utah, EE.UU., 1st June 1940) graduated in Physics at the California Institute of Technology (Caltech) in 1962 and obtained his PhD from Princeton in 1965. In 1966, he returned to Caltech as a research fellow and has developed his entire teaching and research career there. Recognized as one of the most renowned astrophysicists and one of the greatest experts in Einstein’s general theory of relativity, he has been Feynman Emeritus Professor of Theoretical Physics since 2009. Thorne, who learned Russian to be able to read the work of Soviet physicists in the fields of astrophysics and relativity, formed part of the Committee on US-USSR Cooperation in Physics in the late 1970s. In the 1960s and 1970s, Thorne established the theoretical foundations underlying the pulsations of relativistic stars and the gravitational waves they emit. During the 1970s and 1980s, he also developed the mathematical formulation via which astrophysicists analyse the generation of these waves.

He led a research group at Caltech to study the theoretical field of gravitational waves and worked with Vladimir Braginsky, Ronald Drever and Rainer Weiss on new detection techniques. Co-founder of LIGO, Thorne directed its steering committee between 1984 and 1987. During the next three decades, his group’s work focussed on providing theoretical support to LIGO, including the identification of the sources of gravitational waves as targets for this observatory and the rationale for data analysis techniques.

Thorne has also made important contributions to science. Along with Anna Zytkow, he predicted the existence of a network of red supergiant stars with neutron star cores, known as “Thorne-Zytkow Objects”. Together with Igor Novikov and Don Page, he developed the theory of accretion discs around black holes. He jointly derived the laws of motion and precession of black holes from general relativity theory along with James Hartle.

He also invented tools to visualize the curvature of space-time. Together with Saul Teukolsy, in the early 2000s he created the Simulating Extreme Spacetimes (SXS) Project, whose objective is computer simulation of the sources of gravitational waves. These simulations were crucial for extracting information carried by gravitational waves discovered by LIGO. In 2009, he began working with artists, musicians and filmmakers in activities designed to disseminate science among different audiences. One of the fruits of these efforts was his participation in Christopher Nolan’s film Interstellar (2014), in which he figured as executive producer and consultant scientist. He subsequently published the book The Science of Interstellar (2014), which explains the scientific content of the film. This was not his first book for non-scientists, however, as he had already published Black Holes and Time Warps: Einstein’s Outrageous Legacy in 1994.

Holder of honorary doctorates from several universities, Thorne is member of the US National Academy of Sciences, the American Academy of Arts and Science, the American Physical Society, the American Association for the Advancement of Science, the International Society on General Relativity and Gravitation and foreign member of the Russian Academy of Sciences and the Norwegian Academy of Science and Letters. Among other awards, he has received the Julius Edgar Lilienfeld Prize (USA, 1996), the Karl Schwarzschild Medal (Germany, 1996), the Common Wealth Award in Science (USA, 2005), the Albert Einstein Medal (Switzerland, 2009), the Niels Bohr Gold Medal from UNESCO (2010), the Tomalla Prize for Extraordinary Contributions to General Relativity and Gravity (Switzerland, 2016), the Georges Lemaître International Prize (Belgium, 2016) and the Oskar Klein Medal (2016).

Barry C. Barish (Omaha, Nebraska, EE.UU., 27th January 1936) studied Physics at the University of California at Berkeley, where he graduated in 1957 and received his PhD in Experimental Particle Physics in 1962. In 1966, he began working at Caltech, where he has developed his entire teaching and research career. He has been Maxine and Ronald Linde Professor Emeritus of Physics since 2005. At the beginning of his career, Barish conducted outstanding experiments using high energy neutrino collisions to reveal the nucleon quark substructure and participated in the international Monopole, Astrophysics and Cosmic Ray Observatory (MACRO) experiment undertaken in the 1990s in the Gran Sasso tunnel in Italy. Subsequently, Barish set up his research area at the Laser Interferometer Gravitational-Wave Observatory (LIGO), becoming its principal investigator in 1994 and director of the LIGO Laboratory in 1997, a position he held until 2006. As such, he headed the efforts that led to the final design stages, approval of funding by the US National Science Foundation and the construction of LIGO interferometers at Livingston and Hanford.

In 1997, he created LIGO Scientific Collaboration (LSC), which currently comprises 1,167 scientists from the field of physics from more than a hundred universities and institutions from eighteen different countries. Under his leadership, the improvements that led to the further refinement of the facilities were also approved. These refinements were completed in 2014 and converted the interferometers, called Advanced LIGO, into instruments ten times more sensitive than the original ones. Since 2013, he has sat on the executive committee of LIGO Scientific Collaboration. Barish also served as director of the Global Design Effort for the International Linear Collider (ILC) between 2005 and 2013, which has not yet been built, but is to complement the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN).

Barish has served on numerous committees and panels of national and international experts, including the National Science Board, which consists of 24 people who oversee the National Science Foundation and advise the President of the United States and the US Congress on issues related to science, engineering and education. Holder of honorary doctorates from the Universities of Bologna, Florida and Glasgow, Barish is member of the US National Academy of Sciences, the American Academy of Arts and Science, the American Physical Society (which he chaired in 2011) and the American Association for the Advancement of Science, among other organizations.

LIGO Scientific Collaboration (LSC) is a group of 1,167 scientists in the field of physics from more than 100 universities and institutions in eighteen different countries whose main mission is the direct detection of gravitational waves with the aim of using them to explore the fundamental physics of gravity, as well as the research, development and improvement of the techniques for gravitational-wave detection and the development, commissioning and exploitation of gravitational-wave detectors. LSC develops the research carried out by LIGO, the largest gravitational wave observatory and one of the most sophisticated physical experiments in the world. It consists of two huge laser interferometers located more than 3,000 kilometres apart, one in Livingston (Louisiana) and the other in Hanford (Washington). These are two L-shaped laser detectors, each arm of the L being four kilometres long.

The origins of LIGO go back to the 1980s and its initial funding, constituting the largest investment ever made by the US National Science Foundation, was approved in 1992. It is operated by the LIGO Laboratory, a consortium of the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT), and is an international resource for physicists and astrophysicists from around the world. In the 2000s, the detector set was completed with TAMA300 in Japan, GEO600 in Germany and the Virgo Collaboration in Italy. Exploiting the combinations of these detectors, the first joint observations were made in 2002 and concluded in 2010, during which no gravitational waves were detected. Nonetheless, the collected data led to a complete redesign of LIGO’s instruments and facilities. These improvements were carried out up until 2014, when the so-called Advanced LIGO began to operate with a significant increase both in sensitivity and in the volume of the universe to explore.

On 11th February 2016, LSC publicly announced the detection of gravitational waves from the collision and merger of two black holes that occurred on 14th September 2015, when the facilities at Livingston detected the signal from that binary black hole coalescence which occurred around 1,300 million light years away (an event named GW150914). Seven milliseconds later, an identical signal was also received at Hanford. Researchers at Caltech and MIT spent months checking the results before making the announcement. Identification of a second gravitational-wave event (named GW151226), which had been detected on 26th December 2015 by the Livingston and Hanford detectors, was announced on 15th June 2016. The signal, also from two merging black holes, was detected in Livingston 1.1 millisecond before Hanford, which allowed the source of the signal to be calculated as originating 1,400 million light-years away.

On 1st June 2017, LSC announced the third detection of gravitational waves (named GW170104), likewise originating from the merger of a pair of black holes that had occurred on 4th January that year. The three discoveries, accepted for publication in the journal Physical Review Letters, were made by LIGO Scientific Collaboration using data from the LIGO detectors.

LSC receives public and private funding from institutions such as the United States National Science Foundation, the UK Science and Technology Facilities Council, the Max Planck Society (2013 Prince of Asturias Award for International Cooperation) and the State of Lower Saxony (Germany), as well as other agencies in Australia, India, Italy, Spain, Hungary, Korea, Canada, Brazil, Russia, Taiwan and the United States.