Professor B.S. Sathyaprakash
Professor B.S. Sathyaprakash, of the School of Physics and Astronomy at Cardiff University, talks of the quest of black holes, the Big Bang and gravity’s sirens.
Professor B.S. Sathyaprakash
On a wintry evening in December 1996 I had been on the phone with France’s eminent theoretical physicist Thibault Damour in Paris for more than an hour discussing the presentation of our latest research at a meeting the following week. We had worked for the past year on how to detect black holes using a new sort of radiation called gravitational waves that was first predicted by Einstein in 1916. Einstein was himself unsure if they were real or just artefacts of his new theory. From the beginning it was also pretty clear that no laboratory experiment could be set up to produce detectable amounts of this radiation. One was not hopeful of detecting even the most luminous astronomical source with the technology available at the time.
But by mid-1990 all that had changed – technology had advanced and Thibault, an Indian scientist named Bala Iyer, and I were on the verge of proposing a new model of binary black hole sources which would facilitate their detection. I sat speaking to Thibault in my spacious office at Cardiff. Within months of arriving in the UK, I had begun to appreciate how being able to quickly follow-up questions and clarify issues with fellow scientists around the world added immense value to my own research. But that was only possible after identifying many important cultural differences that called for significant changes to my outlook and attitude and required rethinking and readjusting to the new world.
As I write this article sitting in a pretty garden in Tuscany, I am building a dream. Roughly 150 scientists from around the world have come here to discuss the design of a third generation detector called the Einstein Telescope. When completed in 2020, or thereabouts, this ultra-sensitive instrument, which will probably be built in tunnels tens of kilometers underground, could hear the first sounds of gravity that were produced at the birth of our Universe. Bernard Schutz, who was key to my appointment at Cardiff, says in his highly acclaimed popular-science book Gravity from the ground up (Cambridge University Press, Cambridge, 2003) that
“. . . the most exciting possibility of all for the new detectors is that they may be able to detect a background of gravitational radiation in space that originated in the Big Bang, the event that started the expansion of the part of the Universe that we can see”.
Although our signals are going to be in the audio band, and hence the word ‘siren’, they are unlike the familiar sound waves in many respects. They are distortions in the very fabric of space and time caused by colliding black holes. It is going to be a daunting task but our quest is no small matter: our goal is to hear the first sounds of creation.
It was about thirty years ago on a warm November evening that I first heard about black holes during a Science Festival at the National College, Bangalore. The college is famous for organizing the festival each year . The speaker on the day was C.V.Vishveshwara, a young professor at the Raman Research Institute. Vishu’s talk came at a time when I was still debating between music and physics for my career. Vishu had just then published a paper on what would happen to a black hole that is subjected to external forces. The result was totally unexpected. Some of the energy would be absorbed by the black hole but some would be emitted in the form of gravitational radiation. The radiation would pretty much resemble the dying tones of a bell that is struck with a hammer. Vishu’s description of the phenomena was absolutely stunning.
As I walked home that night I built a dream to pursue a career in physics. However, not even in the most ambitious of my dreams did I ever fathom that there will be an opportunity in a land far away from home to realize those dreams. Would we soon hear black holes and the Big Bang via gravity’s outrageous siren? Will the dream really come true?