Nandkumar Kamat
Gravity waves are here now on the agenda of civil society and scientific community. On Valentine’s Day the world has something to celebrate in the perpetual quest of mankind to understand the nature of physical reality. Take time and watch the Hollywood Science Fiction film ‘Interstellar’, based on the same concept.
In April 1992 when the Cosmic Background Explorer (COBE) had discovered the ‘smoking gun of the Big Bang’, the cosmic microwave background radiation signature, astronomer George Smoot said that “it was like seeing The Face of God”. Using that analogy we can now say that the discovery of gravity waves is like feeling the ‘Touch of God”. It is a giant but humbling discovery. It would take some months for the world to soak in and think over the metaphysical and philosophical impacts of this discovery.
For generations to come, people will say: “Do you remember 11 February 2016, when the announcement was made by scientists on LIGO project funded by National Science Foundation, USA about gravity waves?” Even Prime Minister of India, Narendra Modi couldn’t suppress his excitement as he hailed the contributions of Indian gravitational physicists and cosmologists in this discovery.
A little contribution was made by Goa during the International Conference on Gravitation and Cosmology, ICGC, 1987 when cosmologists and experts in gravitational physics from all around the world had assembled in Panaji for five days. Many papers on various approaches to detect gravitational waves had been presented at Hotel Mandovi. All these efforts have now led to India spending ten billion rupees to build a gravitational wave detector and join the network of such detectors across the globe.
We can say that our loving universe has finally opened its heart to mankind by disclosing the real existence of space time continuum and its complex, intricate and really unreal and profoundly mysterious nature. It is more of a mathematical proof than a physical proof. By discovering the presence of gravitational or gravity waves the scientists have proven Albert Einstein correct.
This is an epochal discovery. It appears much more enigmatic when we know that the high energy event, the dancing and then merger of two black holes, which sent the gravity waves had occurred 1300 million years ago – a period when there were neither mammals nor plants on our planet.
How scientists finally reached this milestone? In 1915, Albert Einstein published the general theory of relativity. It had explained how gravity could distort space-time by mass or energy. In 1916, Einstein predicted how massive rotating objects will cause subtle ripples in the fabric of space-time. Idea of gravity waves had remained a scientific curiosity till 1962. Then a paper was published by Russian physicists Gertsenshtein and Pustovoit with a sketch showing optical method for detecting gravitational waves. But it was just the dawn of space age and their idea went unnoticed.
In 1969 Physicist Joseph Weber claimed that he could detect gravitational waves using massive aluminium cylinders. But there was no confirmation of this claim. In 1972 Rainer Weiss of the Massachusetts Institute of Technology (MIT) came out with the idea of using optical method for detecting waves. In 1974 scientists came very close to seeing the proof of existence of gravity waves when astronomers made a Nobel Prize winning discovery. They discovered a pulsar orbiting a neutron star. The surprising slowing down of the neutron star was attributed to gravitational radiation.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) a large-scale physics experiment to detect gravitational waves was approved in 1979 by National Science Foundation (NSF). But only in 1990 NSF sanctioned $250 million to the LIGO experiment. Scientists finally decided on two sites for LIGO in 1992 – Washington and Louisiana – but construction started 2 years later. In 1995, Germany had also begun construction on GEO600 gravitational wave detector. But it began to get data only in 2002. This facility partners with LIGO. In 1996 Italy joined the race to detect gravity waves by constructing VIRGO gravitational wave detector. It began to get data in 2007.
The NSF funded project in USA could not detect any gravity waves in the period 2002-2010. But global scientific collaborations made it possible in 2007 to bring together LIGO and VIRGO teams which agreed to share data. Today they form a single global network of gravitational wave detectors. During 2010 to 2015 LIGO detectors were upgraded raising their capacity and sensitivity. This Advanced LIGO facility began its trial runs in September 2015.
Finally the ‘wow’ moment came in September 2015 itself when a strong signal was recorded at Hanford, Washington and Livingston, Louisiana within a fraction of a second. However, the discipline of science demanded lots of checks, crosschecks and verifications. So the LIGO team waited till February 11 before the discovery was announced. For common man this discovery may not make any difference but for answering some very fundamental questions about the very existence and purpose of the universe – we now have the loving ‘Touch of God’.
The future is very exciting for India in this field and especially for aspiring students aiming to make a career in ‘Big Science’.