Gravitational Wave:
Gravitational wave are ripples in the curvature of the space and time, which are generated in certain gravitational interactions and propagate as waves outward from their source at a speed of light. Their possibility was discussed in 1893.
Introduction:
In 1916, the year after the final publication of the field equations of general relativity, Albert Einstein predicted the existence of Gravitational Waves. He found that linearized weak field equations had wave solutions transverse wave of spatial strain that travel at the speed of light, generated by time variations of the mass quadrupole moment of the source. Similarly in 1916 Schwarzschild published the solution for the field equations that was later understood to describe a black hole. After a century scientists discovered and proved the existence of Gravitational Wave.
Line Source: Observation of Gravitational waves from a Binary Black Hole / American Physical Society
Observatories for Gravitational waves:
- TAMA 300 in Japan
- GEO 600 in Germany
- LIGO in United States
LIGO - Laser Interferometer Gravititaional Wave Observatory:
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| Image Source: American Physical Journal / LIGO Published Paper |
There were two observatories similar to the LIGO. LIGO in Hanford, Washington and another in Livingston, Louisiana. They were constructed with advanced optic mirrors, laser as a source, and detectors. The observatory is in the shape of L of 4x4 kilometers. The mirrors were fixed with anti-shaking technology to avoid unwanted shaking due to earth rotation and some noises around the observatory. Around the long pipe high vacuum is developed to detect a very micro frequency.
Detection:
Two Neutron stars led to the discovery of gravitational wave. One star having 29 solar mass and one another having 36 solar mass collided with high velocity losing 3 solar mass to produce a gravitational waves. The neutron stars collided due to large gravity within them. Finally, their collision resulted in the formation of black hole. In 2015, Advanced LIGO became the first of a significantly more sensitive network of advanced detectors to begin observations. On 14th September 2015, at 09:50:45 UTC, the LIGO Hanford, Washington and Livingston, Louisiana detected the coincident signal GW150914.
When they detected the first wave, they were unable to confirm the wave was really gravitational wave or not. After few years, when they again received and detected the gravitational wave with similar coincident wave at both observatory in Hanford & Livingston. They finalized the Gravitational Wave.
Conclusion:
Gravitational wave was an amazing discovery of this century. After the discovery of Gravitation by Issac Newton and Theory of Relativity by Albert Einstein. It was a mind blowing discovery for further discussion and futuristic discovery about gravitation. It will be a great key for future development and understanding about the Gravity and Gravitation waves and also the formation of Universe. It seems like, very soon our scientists will detect the Gravitons responsible for the Gravity. The future is near. Great Job by LIGO Scientists. Congrats to all the 1000 of scientists who contributed for the discovery of Gravitational Waves.
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