8
The working of LIGO:
LIGO, the largest and most ambitious project ever funded by NSF, consists of two massive L-shaped tubes called interferometers, one in Louisiana and the other in Washington State. Each arm of an L-tube is 4 km in length. Light beams are made to travel along the arms between pairs of mirrors. A passing gravitational wave would stretch space in one direction and shrink it in the perpendicular direction. This would increase the distance between one pair of mirrors and decrease the distance between the other pair. By swinging thus, the mirrors are responding to the stretching and compression of space-time. The minute changes in distance can then be registered by a detector, put in place to record the laser light returning from the two interferometer arms. To ensure that the signal received was an authentic gravitational wave, both interferometers need to do the " dancing mirrors " thing together causing the signal to be picked up by both detectors. When did LIGO detect waves?
On 11 February 2016, the LIGO collaboration announced the detection of gravitational waves, from a signal detected at 09:50:45 GMT on 14 September 2015 of two black holes with masses of 29 and 36 solar masses merging about 1.3 billion light years away. On 15 June 2016, the LIGO group announced the detection of a second set of gravitational waves, which was observed at 03:38:53 GMT on 26 December 2015.
The singularities about LIGO:
● Unlike optical or radio telescopes, LIGO cannot see electromagnetic radiation because gravitational waves are not part of the electromagnetic spectrum.
● As there is no need to collect light from stars or other objects in the Universe, LIGO doesn ' t need to be dish-shaped. LIGO has two long steel vacuum tubes arranged in the shape of an “ L”.
● Gravitational wave observatories like LIGO cannot operate solo. The only way to definitively detect a gravitational wave is by operating in unison with a distant twin.
What other pioneering work is being done? After decades of development and delays, the European Space Agency ( ESA) has given the Laser Interferometer Space Antenna ( LISA) mission there green signal. LISA will use three spacecraft to detect these minute ripples in the fabric of space-time. The spacecrafts will be stationed millions of kilometres apart in space, and linked via laser beams. Each spacecraft carries test masses that are shielded in such a way that the only force they respond to is gravity. Lasers measure the distances to test masses in all three spacecraft. Tiny changes in the lengths of each two-spacecraft arm signals the passage of gravitational waves through the formation.
Thus, gravitational waves are the very foundation of “ new astronomy” - astronomy in which information about new cosmic events will be given not through light but through ripples in the fabric of spacetime itself. Only time can tell what new mysteries gravitational waves might solve.