GRAVITATIONAL WAVES

Gravitational waves were first predicted by Albert Einstein in 1916, a year after the development of his new theory of gravitation known as the general theory of relativity. This theory established gravitation as the curvature of space-time produced by matter and energy. To be discernible even to the most sensitive instruments on Earth, the waves have to be produced by immensely massive objects like black holes and neutron stars which are rotating around each other, or in the extreme situations which prevail in the very early ages of the Universe. This book presents the story of the prediction of gravitational waves by Albert Einstein in 1916, the early attempts to detect the waves, the development of the first LIGO detector and its current form, and the extremely accurate measurements that are needed to detect gravitational waves. That is followed by descriptions of the first detection in 2016, the subsequent detections until the end of 2025, and the many unexpected and very interesting sources which have been found so far. All concepts are described without the use of any mathematics and advanced physics. To set the stage for understanding gravitational waves, the book contains descriptions of electromagnetism, Einstein’s special theory and general theory of relativity, white dwarfs, neutron stars and black holes and other concepts. The book covers these ideas in a simple and lucid fashion which should be accessible to all interested readers. The detection of gravitational waves and related stories, and the LIGO-India project have been widely covered in the print and electronic media. So, the curiosity of the non-technical audience has been aroused about what gravitational waves really are and why they are so important. This book seeks to answer such questions.

Ajit Kembhavi works at the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune. He was the director  and distinguished professor there until August 2015 and later a Raja Ramanna fellow.  He is currently a Visiting Distinguished Professor at IIT-Bombay.  He did his Ph.D. from the Tata Institute of Fundamental Research (TIFR) Mumbai, and was a postdoctoral fellow at the Institute of Astronomy, Cambridge. Professor Kembhavi is a distinguished astronomer who works on galaxies, quasars and other extragalactic objects, various areas of high energy astrophysics including X-ray and radio pulsars, and applications of  AI techniques to astronomy. He has published many research papers and several books. Professor Kembhavi has been a member of the Space Commission and is presently a member of the ISRO’s Apex Science Board. He was a vice-president of the International Astronomical Union, president of the Astronomical Society of India, and president of the Indian Association of General relativity and Gravitation. 
 
Prof. Pushpa Khafre is M.Sc. (Physics) gold medalist from Indore University. She did her Ph.D. in Astrophysics from the Tata Institute of Fundamental Research (TIFR) Mumbai and her postdoctoral work at the Max Planck Institute for Astronomy at Munich, Germany and at the University of Manchester, UK. She then joined as a professor of Physics at the Utkal University, Bhubaneswar, Orissa, in 1983. After retiring from there in 2010, she was CSIR Emeritus Fellow at the Inter-university Centre for Astronomy and Astrophysics, Pune for four years. She had been an associate of IUCAA, since its inception in 1990 till her retirement. She has mainly worked on the Interstellar medium, Quasar absorption lines and Gravitational lensing, and has published more than 50 research papers in international peer reviewed journals.  Professor Khare has visited several institutes around the world for teaching and research. She has been very active in astronomy popularisation and public outreach.