I was born and educated in the USA, and came to Cardiff for my first academic teaching position as a lecturer in 1974. I had obtained my PhD in Physics from the California Institute of Technology in 1971, supervised by Kip Thorne. I also had done postdoctoral work at Cambridge University (in the groups of Stephen Hawking and Martin Rees) and at Yale University (James Bardeen) before coming to Cardiff.

In 1995, then a full professor, I became part time in Cardiff to take a full time position as a director of the new Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam, Germany. I joined Jürgen Ehlers as one of the two founding directors. Since then the institute has grown to have 5 directors and two sites: the second site in Hannover was set up to do experimental gravitational wave research. With over 300 staff, the AEI (as it is known) is the biggest research institute in the world devoted to gravitational science. The AEI has made major contributions to the LIGO detector system, both in technologies and in data analysis, and is the lead institute for the LISA gravitational wave mission of the European Space Agency.

I retired from the AEI in 2014 and returned to Cardiff with a 50% professorship to help set up the new Data Innovation Research Institute, one of several University Research Institutes at Cardiff University. I stepped down from the directorship in 2017. I continue as an Emeritus Director of the AEI.

My research has been recognised by election to a number of learned societies,

• Member, National Academy of Sciences, USA (2019)
• Fellow, Learned Society of Wales (2011)
• Member, Deutsche Akademie der Naturforscher Leopoldina (2006) – Germany’s national academy
• Member, Royal Academy of Arts and Sciences, Uppsala, Sweden (2005)

and by other awards,

• Richard A Isaacson Award for Gravitational-Wave Science of the American Physical Society (2020), shared with my AEI fellow-director Bruce Allen
• Eddington Medal of the Royal Astronomical Society (2019)
• Honorary DSc, Glasgow University (2011)
• Amaldi Gold Medal of the Italian Society for Gravitation (SIGRAV), 2006
• Communitas Award, Max Planck Society (2013)
• Fellow, International Society of General Relativity and Gravitation (2013)
• Honorary Fellow, Royal Astronomical Society (UK, 2009)
• Fellow, American Physical Society
• Fellow, Institute of Physics (UK)

Honours and awards

• Fellow of the Learned Society of Wales, a member of the Deutsche Akademie der Naturforscher Leopoldina
• member of the Royal Academy of Arts and Sciences, Uppsala
• I have been awarded the Amaldi Gold Medal of the Italian Society for Gravitation and the honorary degree of Doctor of Science by Glasgow University
• Honorary Fellow of the Royal Astronomical Society
• Fellow of the International Society for General Relativity and Gravitation
• Fellow of the American Physical Society
• Fellow of the Institute of Physics (UK).

For many years I have taught general relativity and gravitational wave science to undergraduates and MSc students in the School of Physics and Astronomy and its predecessors. My textbook, A First Course in General Relativity (Cambridge University Press) is one of the most widely used introductory texts in the subject worldwide. My textbook on differential geometry, Geometrical Methods of Mathematical Physics (Cambridge University Press), is also widely used at the post-graduate level.

My principal research over the last 40 years has been in the study of the physics and astrophysics of possible gravitational wave sources, including black holes and neutron stars; and in methods of analyzing data from gravitational wave detectors to discover and study gravitational waves.

With J Friedman, I have shown that all rotating stars are vulnerable to an instability that arises from the emission of gravitational waves; one member of this CFS class of instabilities, the r-mode instability, is thought to limit the rotation speed of millisecond pulsars. With K Kokkotas, I discovered a new class of vibrations of relativistic stars, the w-modes, which arise from their coupling to gravitatonal waves. With T Futamase I worked on the foundations of the theory of gravitational radiation. In 1986 I discovered that gravitational waves from binary star systems contain information in their wave-forms that allow us to measure the distance to the system, and I showed how to use that to measure the expansion rate of the Universe, the Hubble-Lemaitre Constant. All detections of binary black hole and neutron star mergers by LIGO and Virgo have used this method to assign a distance, and for the first neutron-star merger (GW170817) it was used to provide a measurement of the Hubble-Lemaitre Constant.

When I moved to Potsdam, Germany, in 1995 to help set up the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) I was able to broaden my research in data analysis and to establish an intensive research effort in numerical relativity. With M-A Papa I helped lay the foundations of the Hough transform method of looking for continuous signals from gravitational wave pulsars, which is the most challenging data analysis problem facing LIGO and its partners. With L Wen I developed the null-stream coherent method for data analysis in systems of three or more detectors, which will see more and more application in the future, particularly for the rejection of spurious noise and possibly for calibration. With P Jaranowski and A Krolak I developed the F-statistic, which is the optimum way to assess the significance of a candidate detection for a continuous signal.

In 1994 I was one of the team that proposed the LISA gravitational wave detector, which is now a mission adopted by the European Space Agency and being developed for launch in 2034. Starting in the late 1990s, my group in Germany began to lay the foundations for the data analysis methods that LISA will use. Also in the 1990s, as a PI of the GEO gravitational wave collaboration (between British and German research groups), I negotiated GEO's alliance with the LIGO gravitational wave project, after which I served on the executive committee of the LIGO Scientific Collaboration (LSC) until 2019. I continue to work within the LSC on gravitational wave detection and astrophysics and with the LISA Consortium on the scientific returns expected from the mission.

Finally I have a strong interest in issues of open access, open data and Big Data in scientific research.