What are gravitational waves? What does the discovery of it hold for the world? What is the contribution of India towards this project? (250 W)

Mentors Comment:

The demand of the question is straight forward.

You can use the first part of the question as your intro and simply discuss what are gravitational waves.

The second part will have the discussion on their importance to the world. This you have to discuss in bullet points, preferably.

The last part will be the role of Indian science community in the program and what benefit it holds for us.

Conclude the answer with mini paragraph. 

Answer:

Gravitational waves:
• Gravitational waves are ‘ripples’ in the fabric of space ­time caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity.
• Einstein’s mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space­time in such a way that ‘waves’ of distorted space would radiate from the source (like the movement of waves away from a stone thrown into a pond).
• Furthermore, these ripples would travel at the speed of light through the Universe, carrying with them information about their cataclysmic origins, as well as invaluable clues to the nature of gravity itself.

Significance:
• Detecting two colliding black holes is thrilling as no one knew for sure if black holes actually merged together to create even more ­massive black holes, but now there’s physical proof. • And there’s direct evidence for a phenomenon that was first predicted 100 years ago, using an instrument that was proposed 40 years ago.
• With this discovery emerges not only a pattern among black holes but also possibilities of gravitational wave astronomy, detection of new heavenly bodies and gaining a better understanding of that most elusive of theories Einstein’s general theory of relativity, and the fundamental force of gravitation.

How does LIGO detect gravitational waves?
• The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large ­scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational ­wave observations as an astronomical tool.
• Two large observatories were built in the United States with the aim of detecting gravitational waves to laser interferometry
• When a gravitational wave passes through the interferometer, the space time in the local area is altered. Depending on the source of the wave and its polarization, this results in an effective change in length of one or both of the cavities.
• The effective length change between the beams will cause the light currently in the cavity to become very slightly out of phase (antiphase) with the incoming light.
• The cavity will therefore periodically get very slightly out of coherence and the beams, which are tuned to destructively interfere at the detector, will have a very slight periodically varying detuning. This results in a measurable signal.
• The experimental data not only validates relativity but also provides a novel method of studying astronomical objects that are at a great distance from us simply by considering the gravitational waves they produce.

Indian contribution:
• The paper published on the discovery of gravitational waves had 1004 authors and among them were many Indians.
• In the preface, Laser Interferometer Gravitational ­Wave Observatory (LIGO) of India gets a significant mention where it says, ‘the LIGO detector in India will extend the network and significantly improve the position reconstruction and parameter estimation of sources’
• With nearly 67 Indians from 13 institutions across the country taking part in the theory and experiment
• This experiment opens many new areas for India for which it already set up research work in many elite institutes across India.
• LIGO­Indiaor INDIGO, is a planned collaborative project between the LIGO Laboratory and the Indian initiative in gravitational (IndIGO) to create a world­ class gravitational ­wave detector in India will extend the network and significantly improve the position reconstruction and parameter estimation of sources.