IASTopper-Gravitational-Waves
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Mains Articles

Gravitational Waves

It will open up new frontier for understanding of universe.
By IT' Mains Articles Team
April 11, 2016

Contents

  • Why we study gravitational waves in detail?
  • First thing, what are these gravitational waves?
  • Significance of Gravitational Waves
  • Albert Einstein
  • Ligo
  • Role of Indian Scientists

        Around 100 years ago, Albert Einstein had predicted the gravitational waves which are now confirmed and detected by the Laser Interferometer Gravitational Observatory (LIGO) — specialised laboratories in Louisiana and Washington in the US. 


Why we study gravitational waves in detail?


For two reasons:

  1. Because it is a landmark achievement in the history of scientific developments.
  2. The detection was also contributed to by a group of Indian scientists.


First thing, what are these gravitational waves?


In Brief:


Gravitational waves are ‘ripples’ or disturbances in the fabric of space-time.  They are produced when whole black holes collide and stars explode.

These waves are sound track of cosmos.


Practical Examples:

 

  • If you drag your hand through a still pool of water, you’ll notice that waves follow in its path, and spread outward through the pool. The same thing happens when heavy objects move through space-time.
  • One famous way of visualizing this is to take a taut rubber sheet and place a heavy object on it. That object will cause the sheet to sag around it. If you place a smaller object near the first one, it will fall toward the larger object.

A star exerts a pull on planets and other celestial bodies in the same manner.


In details:


Although, physics supports the existence of gravitational waves, the strength of such waves even due to astronomically heavy bodies is awfully weak to be detected.

There are four types of Gravitational Waves categorized by LIGO:

  1. Continuous Gravitational Waves,
  2. Compact Binary in spiral Gravitational Waves,
  3. Stochastic Gravitational Waves, and
  4. Burst Gravitational Waves.


Significance of Gravitational Waves:


Discovery of gravitational waves would represent a scientific landmark, opening the door to an entirely new way to observe the cosmos and unlock secrets about the early universe and mysterious objects like black holes and neutron stars.

  • As vibrations in the fabric of space-time, gravitational waves are often compared to sound, and have even been converted into sound snippets. Gravitational-wave telescopes allow scientist to ‘hear’ phenomena at the same time as light- based telescopes ‘see’ them.
  • The ability to detect them has the potential to revolutionize astronomy.
  • This discovery is the first detection of a black hole binary system and the first observation of black holes merging. These waves are a ripple in the invisible fabric of the universe, called the space-time continuum which was propounded by Albert Einstein.
  • Gravitational waves could also help physicists understand the fundamental laws of the universe.
  • Gravitational waves are important in telling about the early universe.


Three names revolve around GWs:

 

  1. Albert Einstein (who predicted)
  2. LIGO (who detected)
  3. A group of Indian scientists (who contributed)


Albert Einstein


Around 100 years ago, Albert Einstein’s general theory of relativity had predicted the gravitational waves. (Almost everything the theory predicted has been confirmed by observation or experiment, except gravitational waves.)

Albert-Einstein

  • Einstein’s theory showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that ‘waves’ of distorted space would radiate from the source.
  • 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.
  • Gravitational waves cannot exist in the Newtonian theory of gravitation, since Newtonian theory postulates that physical interactions propagate at infinite speed.

GWs


LIGO


The Laser Interferometer Gravitational-Wave Observatory known as LIGO is a large-scale physics experiment aiming to directly detect gravitational waves.

LIGO_Hanford_Observatory_620x331

  • LIGO has been searching for these cosmic ripples for over a decade. Last September, it upgraded to Advanced-LIGO, a more sensitive system that’s also better at filtering out noise. Advanced-LIGO has a much stronger chance of collecting concrete evidence of gravitational waves.
  • LIGO operates two gravitational wave observatories in unison:
  1. The LIGO Livingston Observatory in Louisiana, and
  2. The LIGO Hanford Observatory, Washington.

These sites are separated by 3,002 kilometers. Since gravitational waves are expected to travel at the speed of light, this distance corresponds to a difference in gravitational wave arrival times of up to ten milliseconds.

IASToppers-LIGO-Functioning

The LIGO work is funded by the National Science Foundation, an independent agency of the U.S. government.


Role of Indian Scientists


The Indian scientists also have contributed significantly for finding out for gravitational waves.

  • Earlier in 1971, the theory of black holes merging was predicted by Indian Scientist C V Vishweshwara.
  • Inter University Centre for Astronomy and Astrophysics (IUCCA) is one of 15 institutes in the country associated with the LIGO project, but the centre incubated the project since the beginning.
  • The detection was also contributed to by INDIGO (Indian Initiative in Gravitational Wave Observations).
  • IUCAA was involved in the project from the time gravitational waves were not taken seriously in India.

 

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