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38) Republic Day 2020 Parade HIGHLIGHTS: Colourful tableaux, daredevilry, navy might on display

India Republic Day -- Indian Republic Day 2020 March, Flag Hosting HIGHLIGHTS: Primary Minister Narendra Modi paid his tributes to martyrs by laying a wreath at the National War Memorial in the presence of Support Minister Rajnath Singh, 3 service chiefs and Main of Defence Staff Bipin Rawat. India Republic Moment Parade 2020, Flag Web hosting service HIGHLIGHTS: India is celebrating its 70th Republic Moment Today. The celebration at Rajpath started with Primary Minister Narendra Modi paying out homage to the fallen troopers at the newly-built National War Memorial on the Republic Moment for the first time instead of the Amar Jawan Jyoti beneath the India Door arch. This was followed by President Ram Nath Kovind unfurling the tricolour. The occasion marks the day when India’s Constitution came into effect, along with the country became a republic. Heavylift helicopter Chinook and also attack helicopter Apache, each recently inducted in the Indian Air Force, took part from the Repub...
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LIGO

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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 by laser interferometry. These observatories use mirrors spaced four kilometers apart which are capable of detecting a change of less than one ten-thousandth the charge diameter of a proton. The initial LIGO observatories were funded by the National Science Foundation (NSF) and were conceived, built and are operated by Caltech and MIT. They collected data from 2002 to 2010 but no gravitational waves were detected. The Advanced LIGO Project to enhance the original LIGO detectors began in 2008 and continues to be supported by the NSF, with important contributions from the United Kingdom's Science and Technology Facilities Council, the Max Planck Society of Ger...
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History

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Background edit The LIGO concept built upon early work by many scientists to test a component of Albert Einstein's theory of general relativity, the existence of gravitational waves. Starting in the 1960s, American scientists including Joseph Weber, as well as Soviet scientists Mikhail Gertsenshtein and Vladislav Pustovoit, conceived of basic ideas and prototypes of laser interferometry, and in 1967 Rainer Weiss of MIT published an analysis of interferometer use and initiated the construction of a prototype with military funding, but it was terminated before it could become operational. Starting in 1968, Kip Thorne initiated theoretical efforts on gravitational waves and their sources at Caltech, and was convinced that gravitational wave detection would eventually succeed. Prototype interferometric gravitational wave detectors (interferometers) were built in the late 1960s by Robert L. Forward and colleagues at Hughes Research Laboratories (with mirrors mounted on a vibration isola...
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Mission

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LIGO's mission is to directly observe gravitational waves of cosmic origin. These waves were first predicted by Einstein's general theory of relativity in 1916, when the technology necessary for their detection did not yet exist. Their existence was indirectly confirmed when observations of the binary pulsar PSR 1913+16 in 1974 showed an orbital decay which matched Einstein's predictions of energy loss by gravitational radiation. The Nobel Prize in Physics 1993 was awarded to Hulse and Taylor for this discovery. Direct detection of gravitational waves had long been sought. Their discovery has launched a new branch of astronomy to complement electromagnetic telescopes and neutrino observatories. Joseph Weber pioneered the effort to detect gravitational waves in the 1960s through his work on resonant mass bar detectors. Bar detectors continue to be used at six sites worldwide. By the 1970s, scientists including Rainer Weiss realized the applicability of laser interferometry ...
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Observatories

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LIGO operates two gravitational wave observatories in unison: the LIGO Livingston Observatory ( 30°33′46.42″N 90°46′27.27″W  /  30.5628944°N 90.7742417°W  / 30.5628944; -90.7742417 ) in Livingston, Louisiana, and the LIGO Hanford Observatory, on the DOE Hanford Site ( 46°27′18.52″N 119°24′27.56″W  /  46.4551444°N 119.4076556°W  / 46.4551444; -119.4076556 ), located near Richland, Washington. These sites are separated by 3,002 kilometers (1,865 miles) straight line distance through the earth, but 3,030 kilometers (1,883 miles) over the surface. 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. Through the use of trilateration, the difference in arrival times helps to determine the source of the wave, especially when a third similar instrument like Virgo, located at an even greater distance in Europe, is added. Each observatory supports an L-shaped ultra ...
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Operation

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The parameters in this section refer to the Advanced LIGO experiment. The primary interferometer consists of two beam lines of 4 km length which form a power-recycled Michelson interferometer with Gires–Tournois etalon arms. A pre-stabilized 1064 nm Nd:YAG laser emits a beam with a power of 20 W that passes through a power recycling mirror. The mirror fully transmits light incident from the laser and reflects light from the other side increasing the power of the light field between the mirror and the subsequent beam splitter to 700 W. From the beam splitter the light travels along two orthogonal arms. By the use of partially reflecting mirrors, Fabry–Pérot cavities are created in both arms that increase the effective path length of laser light in the arm. The power of the light field in the cavity is 100 kW. When a gravitational wave passes through the interferometer, the spacetime in the local area is altered. Depending on the source of the wave and its polarization, this results in ...
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Observations

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Based on current models of astronomical events, and the predictions of the general theory of relativity, gravitational waves that originate tens of millions of light years from Earth are expected to distort the 4-kilometre (2.5 mi) mirror spacing by about 10−18 m , less than one-thousandth the charge diameter of a proton. Equivalently, this is a relative change in distance of approximately one part in 10 21 . A typical event which might cause a detection event would be the late stage inspiral and merger of two 10-solar-mass black holes, not necessarily located in the Milky Way galaxy, which is expected to result in a very specific sequence of signals often summarized by the slogan chirp, burst, quasi-normal mode ringing, exponential decay. In their fourth Science Run at the end of 2004, the LIGO detectors demonstrated sensitivities in measuring these displacements to within a factor of 2 of their design. During LIGO's fifth Science Run in November 2005, sensitivity reached th...
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