Albert Einstein predicted the existence of gravitational waves in 1916 based on his general theory of relativity. But even he doubted their existence. In 1936, twenty years after he first introduced the concept, Einstein submitted with his collaborator N. Rosen, a paper, titled Do gravitational waves exist?, to the Physical Review Letters, where he arrived at the surprising conclusion that gravitational waves do not exist. The same year, he wrote in a letter to his friend Max Born.
“Together with a young collaborator, I arrived at the interesting result that gravitational waves do not exist, though they had been assumed a certainty to the first approximation. This shows that the non-linear general relativistic field equations can tell us more, or rather, limit us more than we have believed up to now.”
But Einstein was wrong. Soon the reviewer found holes in his math, and he returned the manuscript with a critical review. Not pleased, Einstein withdraw the paper with the promise not to publish to Physical Review Letters ever again. His paper was, however, subsequently accepted for publication by the Journal of the Franklin Institute in Philadelphia, where it appeared with radically altered conclusions in early 1937.
And then, 100 years after Albert Einstein’s 1915 general theory of relativity, on September 14, 2015 at 5:51 a.m. EDT, the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, one located in Hanford, Washington, and the second in Livingston, Louisiana, USA, measured ripples in the fabric of space-time. These distortions are caused by some of the most violent and catastrophic events in the universe, such as colliding black holes, and the collapse of stellar cores (supernovae). They are so massive that they disrupt the very fabric of space and time itself. These distortions in the fabric of space-time are gravitational waves.
The detection of gravitational waves (an exceedingly faint signal) is a monumental breakthrough in science. It came after decades of research, through a world-wide effort of thousands of scientists and it marks the beginning of a new era of gravitational wave astronomy.
LIGO detectors is one of the most excited and complicated scientific facilities. Each detector is shaped like a giant L, each leg four kilometers long. Laser light bounces back and forth through the legs, reflecting off mirrors, while precise atomic clocks measure how long it takes to make the journey.
In her book, Black Hole Blues and Other Songs from Outer Space, Janna Levin, a professor of physics and astronomy at Barnard College, explores the LIGO project, from its humble beginnings, about forty years ago, as the dream of Rainer Weiss, to the years-long effort and dedicated work of Rainer Weiss, Kip Thorne and Ron Drever, a trio that is also known as the troika, to its exciting and successful completion.
The book is a chronicle of gravitational waves, “a soundtrack to match the silent movie – it is a tribute to a quixotic, epic, harrowing experimental endeavor, a tribute to a fool’s ambition,”as described in the book. It is equally divided between the science and the story of the people behind the endeavour, their dreams and their challenges, the drama and the excitement, the failures and the clashes of huge egos. Levin avoids using technical jargon and difficult scientific concepts associated with black holes. Very good read.
“Scientists are like those levers or knobs or those boulders helpfully screwed into a climbing wall. Like the wall is some cemented material made by mixing knowledge, which is a purely human construct, with reality, which we can only access through the filters of our minds. There is an important pursuit of objectivity in science and nature and mathematics, but still the only way up the wall is through the individual people. And they come in specifics – the French guy, the German guy, the American girl. So the climb is personal, a truly human endeavor, and the real expedition pixelates into individuals, not Platonic forms. In the end it’s personal, as much as we want to believe it’s objective.”
- A. Einstein , The Born–Einstein Letters: Friendship, Politics, and Physics in Uncertain Times, MacMillan, New York (2005), p. 122.
- Einstein, A., Rosen, N., On gravitational waves, Journal of the Franklin Institute, Volume 223, Issue 1, January 1937, Pages 43-54
- Featured image source: http://lisa.jpl.nasa.gov/popups/ripples.html