Discorsi di ringraziamento – Berna, 01.07.2022 (video + testi, inglese)

Italia/USA e Francia

Alessandra Buonanno e Thibault Damour

Premio Balzan 2021 per gravità: aspetti fisici e astrofisici

Per il loro ruolo guida nella predizione dei segnali di onde gravitazionali prodotti quando oggetti molto compatti, come stelle di neutroni e buchi neri, spiraleggiano uno intorno all’altro, e infine si fondono in un unico oggetto. Il loro lavoro è stato fondamentale per la prima rilevazione delle onde gravitazionali, fornendo una conferma estremamente accurata della relatività generale come teoria della gravi-tazione. Ha inoltre permesso ai rilevatori LIGO e Virgo di promuovere un tipo di astronomia che utilizza le onde gravitazionali come nuovi e potenti messaggeri dell’universo.

Acceptance speech
by Alessandra Buonanno

President of the National Council,
Members of the Balzan Foundation,
Ladies and gentlemen:

It is with profound thanks to the Balzan Foundation and the Balzan General Prize Committee that I accept this generous award. I am deeply honored and humbled that my name is included in the list of so many distinguished Balzan Prizewinners.

I am delighted that the Balzan Prize Committee has recognized the topic of theoretical predictions of gravitational waves from binary systems, and I am also very pleased to share this prize with Thibault Damour.

I entered the research field of gravitational waves through a series of somewhat unanticipated events. Indeed, after a PhD thesis in theoretical cosmology, my scientific interest started to drift toward gravitational waves from binary systems during the first year of my postdoctoral time at the Institut des Hautes Etudes Scientifiques (IHES), where with Thibault Damour we invented the effective-one-body approach. Such switch was also triggered by the attendance of an inspiring workshop where the first attempts to analyze data of a 40-meter gravitational-wave detector to search for signals from binary systems were discussed. Subsequently, I made the key decision to devote my research to gravitational waves, instead of cosmology, when I accepted a fellowship at Caltech, where I highly benefited from interactions with astrophysicists, data analysts and experimentalists.

I am grateful to other research opportunities that I had along my scientific career, including collaborations with worldwide experts in analytical relativity when working at the Institut d’Astrophysique de Paris, and with numerical-relativity pioneers, immediately after the attendance of a workshop at NASA Goddard, nearby the University of Maryland, where the numerical waveforms produced by the merger of two black holes were first independently confirmed. I am also thankful to the University of Maryland and the Max Planck Society for the very generous funds and the academic freedom it has made available to me that have allowed me to quickly build, from scratch, an interdisciplinary research group, which spans from theory to observation through the analysis of experimental data, and be at the forefront of gravitational-wave astronomy from day one, when the advanced LIGO detectors came online in 2015. Indeed, on September 14, 2015, the LIGO and Virgo Collaboration observed for the first time a gravitational wave emitted by the collision of two black holes.

Today, after almost seven years, we have observed about 100 gravitational waves, emitted by the merger of black holes and neutron stars, ushering in the field of multi-messenger astronomy with gravitational waves. This number will grow considerably over the next several years, as the sensitivity of the instruments improves. In the next decade, new frequency bands will be opened.
There will be new facilities on the Earth, such as the Einstein Telescope and Cosmic Explorer, which will observe binary black holes at the time the first stars formed, and a mission in space, LISA, which will observe gravitational waves from black holes of millions of solar masses, such as the one at the center of our own galaxy.

I feel lucky to have experienced firsthand the discovery of gravitational waves from merging black holes in 2015, and the observation of the first neutron-star coalescence in 2017. Great breakthroughs in science often occur by undertaking projects that seem impossible to accomplish. Forty years ago, the proponents of LIGO and Virgo, theorists and experimentalists, had the sagacity and ingenuity to build new instruments to observe the universe and detect gravitational waves for the first time on the Earth.
Not only. They also had the courage and determination to persuade science funding agencies and many other scientists to embark on these somewhat risky projects. I think it is exceptional what women and men can achieve with their creativity, intellectual freedom and ingenuity, and their love for knowledge.

Science is a collective activity. The scientific insights that I have gained over the last twenty years in developing state-of-the-art waveform models for gravitational-wave observations and science were gained together with my senior and junior collaborators, notably postdoctoral scholars and PhD students, and my colleagues of the LIGO and Virgo collaboration. I dedicate the Balzan Prize to all of them.

I was very fortunate to grow up in an environment that did not prevent me to follow my passions and curiosity, and achieve a scientific career. I want to thank my parents and my scientific mentors who nurtured my independence, and encouraged me to take advantage of opportunities, as they arose.

Once again, I thank you for this wonderful honor. I am using my Balzan Prize to support junior scientists in a research project, in collaboration with historians and philosophers of science, on the path to the solution of the two-body problem in General Relativity in the last 30 years, and its impact in the first observation of gravitational waves.

Acceptance speech
by Thibault Damour

Madame la présidente du Conseil national,
Members of the Balzan Foundation,
Dear Colleagues,
Ladies and Gentlemen,

It is for me a singular honor – and a great emotion – to receive the Balzan Prize for advances in the physical and astrophysical aspects of gravitation. The work for which Alessandra Buonanno and I receive the Balzan Prize today is the invention of a formalism (called Effective One-Body) that yields an analytical description of the gravitational wave signal generated by coalescing binary black hole systems.

The Effective One-Body formalism gave the first complete description of the gravitational wave signal from the slowly evolving sinusoidal wave emitted during the early inspiral until the intense flash of gravitational radiation generated during the merger, ending in exponentially damped oscillations. This formalism was constructed and then developed by combining, in a novel way, insights and knowledge due to many authors. In this respect, I would like to acknowledge the crucial help in informing and developing the Effective One-Body formalism of many of my collaborators, notably Luc Blanchet, Gerhard Schaefer, Piotr Jaranowski, Bala Iyer, Alessandro Nagar, Luciano Rezzolla, and Donato Bini.

I wish also to acknowledge the insights in gravitational physics I got many years ago during my postdoctoral stay at Princeton University, notably through my interactions with Remo Ruffini and John Wheeler. Indeed, science is, by essence, a cumulative endeavor.

The cumulative character of science is well encapsulated in the famous sentence that every generation of scientists can see further only because they stand on the shoulders of giants. In this respect, it is particularly fitting to receive the Balzan Prize for Gravitation here in Bern, where in 1907 the greatest giant of 20th century physics, Albert Einstein, had the fundamental insight that led him to a new theory of gravitation: general relativity. Besides the key contributions of luminaries such as Einstein, scientific progress is based on collaboration and discussion with colleagues, students, and postdocs.

I can therefore only accept the Balzan Prize with humility, as a representative of the community of theoretical physicists. In accepting the Balzan Prize, I am particularly happy for the rule that half of the prize should be used to involve an international group of young researchers. This will allow me to pay my debt for the insights – and help – I got from many fellow scientists over many years.
Thank you for your attention.

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