On the occasion of National Technology Day(11th May), Prime Minister Narendra Modi laid the foundation stone of multiple scientific projects worth more than Rs 5800 crore. One of the most significant projects is the Laser Interferometer Gravitational-Wave Observatory, the Prime Minister said, &quot;LIGO-India will include us in one of the few countries to have such observatories in the world. It will give our students and scientists new and advanced opportunities.&quot;<br />”<br />”The LIGO-India, to be developed in Hingoli, Maharashtra, will be one of the handful Laser Interferometer Gravitational-wave observatories in the world. It is an extremely sensitive interferometer of 4 km arm length, the interferometers act as 'antennae' to detect gravitational waves. The LIGO-India will work in synchronization with two observatories operating in the United States; one in Hanford, Washington, and the other in Livingston, Louisiana. When LIGO-India is completed, it will join a global network of gravitational-wave observatories that includes Virgo in Italy and KAGRA in Japan.<br />”<br />”<br />”What are Gravitational Waves: A gravitational wave is an invisible (yet incredibly fast) ripple in space. Gravitational waves travel at the speed of light (186,000 miles per second). These waves squeeze and stretch anything in their path as they pass by.<br />”<br />”Einstein predicted that something special happens when two bodies’such as planets or stars’orbit each other. He believed that this kind of movement could cause ripples in space. These ripples would spread out like the ripples in a pond when a stone is tossed in. Scientists call these ripples of space gravitational waves.<br />”<br />”What causes gravitational waves?<br />”<br />”The most powerful gravitational waves are created when objects move at very high speeds. Some examples of events that could cause a gravitational wave are: when a star explodes asymmetrically (called a supernova), when two big stars orbit each other, and when two black holes orbit each other and merge.<br />”<br />”But these types of objects that create gravitational waves are far away. And sometimes, these events only cause small, weak gravitational waves. The waves are then very weak by the time they reach Earth. This makes gravitational waves hard to detect.<br />”<br />”How do we know that gravitational waves exist?<br />”<br />”In 2015, scientists detected gravitational waves for the very first time. They used a very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave Observatory). These first gravitational waves happened when two black holes crashed into one another. The collision happened 1.3 billion years ago. But, the ripples didn’t make it to Earth until 2015!<br />”<br />”The first detection of gravitational waves was a very important event in science. Before this, just about everything we knew about the universe came from studying waves of light. Now we have a new way to learn about the universe’by studying waves of gravity.<br />”<br />”Gravitational waves will help us learn many new things about our universe. We may also learn more about gravity itself!<br />”<br />”How are gravitational waves detected?<br />”<br />”When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two ‘arms’ that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.<br />”<br />”LIGO – India and its role in Unlayering the cosmic mystery: The Government will spend about $320 million to build LIGO-India, with first observations expected by the end of the decade. When LIGO-India will be completed, it will join a global network of gravitational-wave observatories that includes Virgo in Italy and KAGRA in Japan. With its advanced gravitational-wave-sensing technology, LIGO-India will greatly improve the ability of scientists to pinpoint the sky locations of the sources of gravitational waves. Because of its location on Earth with respect to LIGO, Virgo, and KAGRA, it will also fill in blind spots in the current gravitational-wave network.<br />”<br />”The gravitational waves that LIGO detects are caused by some of the most profoundly cataclysmic events in the Universe, colliding black holes, merging neutron stars, exploding stars, and possibly even the birth of the Universe itself. Detecting and analyzing the information carried by gravitational waves allows researchers, astronomers, and other scientists to glimpse into un-seeable wonders.<br />”<br />”The Professor of Physics at Caltech, Rana Adhikari observed that the observatory would increase the precision with which gravitational-wave events are observed. He added, &quot;This will greatly enhance our ability to answer fundamental questions about the universe, including how black holes form and the expansion rate of our universe, as well as to more rigorously test Einstein's general theory of relativity.&quot;<br />”<br />”Taking forward the learnings from Einstein: Albert Einstein predicted the existence of gravitational waves in 1916, and it took almost a century for scientists to detect them directly. The first indirect evidence of gravitational waves was discovered in 1974 by two astronomers using the Arecibo Radio Observatory. They observed a binary pulsar and found that its stars were getting closer to each other at precisely the rate predicted by general relativity if they were radiating gravitational waves.<br />”<br />”Further confirmations of gravitational waves were made by studying pulsar radio emissions. However, the direct detection of gravitational waves happened on 14th September 2015, when LIGO physically sensed the undulations in space-time caused by two colliding black holes 1.3 billion light-years away. This detection marked one of humanity's greatest scientific achievements.<br />”<br />”While the processes that generate gravitational waves are violent and destructive, the waves that reach Earth are thousands of billions of times smaller and diminish over time and space. LIGO was designed to make inconceivably small measurements, allowing scientists to detect these waves.<br />”<br />”The LIGO-India project would further open new avenues for exploring the universe. The scientific project is a collaboration between the LIGO Laboratory (operated by Caltech and MIT) and three Institutes in India: the Raja Ramanna Center for Advanced Technology (RRCAT, in Indore), the Institute for Plasma Research (IPR in Ahmedabad), and the Inter-University Centre for Astronomy and Astrophysics (IUCAA), in Pune.<b><br />”</b><br />