According to Einstein’s General Theory of Relativity, gravity is the phenomenon resulting from the curvature of space time fabric and mass is the gravitational effect that curves space time sheet. When two massive bodies are accelerating through the space time, the curvature of the space time gets distorted and that passes through the fabric with a velocity of light in free space in a wave like manner. This is called Gravitational Wave which are the ripples formed on space time fabric. It can be within 10-7Hz to 1011Hz. Gravitational Wave can penetrate more regions in the space that’s why it allows us a deep observation about the objects in the distant galaxies and the merger of the black hole, but EM wave has some restrictions respect to GW. Due to GW, distance between two bodies gets increased and decreased in a rhythmic way and that forms an oscillation which has the same frequency as that of GW. Basically a binary neutron star system, black holes are the source of GW. A binary neutron star system that is rotating around each other(shown in fig.) in an in-spiral motion, comes closer to each other due to loss of energy and collide and generates GW. Besides, two objects orbiting around each other, will orbit the sun and form GW. A supernova will radiate except in the unlikely event that the explosion is perfectly symmetric. Like the sound, water and other EM waves, GW also carries energy, linear and angular momentum etc. and gets spread away from the source. As, in this case, gravity itself is the cause of distortion of space time, that’s why the red shifting of GW is different from the red shifting due to gravity. GW is detected by LIGO(Laser Interferometer Gravitational Wave Observatory). The principle of LIGO depends on theMichelson Interferometer. LIGO has been proposed in India. The primary interferometer consists of two arms of 3-4 km in length that forms power recycled interferometer. The two separated beams recombine at the beam splitter and they are kept out of phase, light waves subtract and no light should arrive at the photo diode. When a GW is passing through the interferometer, the distance along the arms are shortened and lengthened, causing the beams to be slightly out of phase. This results in the beams coming in phase and some light arrives at the photo diode. Light that doesn't contain any signal is back to the interferometer using a power recycling mirror. Observers compare the signals from both sites to reduce the effect of noise. Thus, LIGO is detecting GW and conducting observations to collect informations about the deep universe. Many of them has successfully been completed and many are under processing. It’s now has been one of the most demanding branches of space science and is a great mile stone for future obviously.
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