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Gravitational Waves - Discovery of the Century

The announcement by the Scientists on 11th February 2016 about the discovery of 'Gravitational...

👤 Dr R Jagannathan1 March 2016 1:37 PM GMT
Gravitational Waves - Discovery of the Century
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The announcement by the Scientists on 11th February 2016 about the discovery of 'Gravitational waves', the ripples in the fabric of space-time, electrified the world of astronomy and scientists. This is the discovery of the century as the gravitational waves were predicted by Albert Einstein in 1916. In 1979, National Science Foundation funded California Institute of Technology and Massachusetts Institute of Technology to detect the waves. They set up Laser Interferometer Gravitational Observatory (LIGO) detectors to conduct the study.

Prime Minister Narendra Modi lauded the role of Indian Scientists who were part of the team that discovered the 'Gravitation waves'. "The historic detection of gravitational waves will open up new frontier for understanding of universe. Hope to move forward to make even bigger contribution with an advanced gravitational wave detector in the country", he tweeted.

Gravitational waves explained

We know that a stone tossed up, falls back to Earth because of its gravitational force that draws the stone to the earth. We have the Newton's law to explain and measure the force of gravity. This explanation is sufficient for theoretical understanding. What really happens is the following:

Imagine that two of us hold the four corners of a handkerchief so that the piece of cloth is now a plane surface. Now, imagine placing a very heavy iron ball at the centre of the handkerchief. The shape of the handkerchief gets curved as shown in the figure.

The curved space around a massive object like a star is called Space-Time fabric, since it is not just a change in length-breadth-width that occurs. Time changes too in this curvature. Therefore, a stone thrown above the earth travels back through this curvature of space-time and ultimately touches the central massive body (Earth), an action we term as the stone falling back on Earth.

If the central massive object remains at rest, or moves at a steady and consistent speed, the curvature of the space-time remains at rest, or moves at the same speed. But if the central mass moves with acceleration, then the changes of curvature of this space-time fabric generates gravitational waves. These waves propagate in space at the speed of light.

Einstein predicted the existence of these gravitational waves in 1916 itself as a consequence of his General Theory of Relativity.

Detection of These Waves

About 1.3 billion years ago, two black holes, each having a mass of about 30 times our Sun, attracted each other and collided with each other producing intense gravitational waves. INTENSE means these waves have a wavelength measuring millions of miles but with a sub-millimetre height. To detect such an extremely weak gravitational wave, the Laser Interferometer Gravitational Observatory (LIGO) Team in USA made a pair of coherent laser beams to travel in mutually perpendicular paths of about 4 km each in length and recorded the changes in the path lengths by observing an unambiguous interference pattern when these gravitational waves were crossed in the observatory. Had Einstein been alive today, he would have been amazed at the technology that enabled this detection.

The Significance of This Discovery

· For the first time we have direct evidence of a black-hole, rather two black-holes of about 30 solar masses colliding with each other, as predicted by Einstein.

· The gravitational waves that are now detected matched exactly with what Einstein had predicted.

Where Does This Discovery Lead Us To?

· Just as we have optical and radio telescopes to observe our Universe in-depth, we can now observe through gravitational-waves-interferometers, which can give us unblurred details.

· Our Universe has energy distribution roughly as follows: 68% dark energy, 27% dark matter and 5% normal matter.

· Remember that we are all made up of normal matter and hence currently, we can perceive only this 5% of the Universe. With this discovery, we can now probe the dark matter too since they have "mass" and can give rise to gravitational waves.

· We can see the Universe close-up to 2 or 3 seconds of its formation! The gravitational waves will pave the way to look in to such a nascent Universe. ( please note that we are now able to look at the Universe only after 0.28 billion years of its birth).

Benefits to a Common man

When the experiment at European Organization for Nuclear Research popularly known by the French acronym CERN, Geneva, was organised to detect the "GOD" particle, the scientists had the necessity to interlink many of their research computers, which gave the world the "World Wide Web" (www). The LIGO Labs in India (to be established soon) can now bring distinct advantages to our scientists, researchers, students, the government and the entire country.

The precision of the measurements involved in the detection of gravitational waves are so high that

  1. · early warning systems for disasters like tsunami will be absolute, correct and more reliable on the dot.
  2. · analysis and understanding of DNAs at the bond-level is possible and this can throw more light in understanding healthy and diseased conditions, leading to stunning biological discoveries.
  3. · it will give an unprecedented ability to process really big data, giving a direct advantageous edge – the following list is only indicative and not complete – to our military, disaster management and crisis management.

Please watch this video to get the visual details.

By Dr R. Jagannathan, Editorial Advisor, PreSense