Image Credit: LIGO, https://skyandtelescope.org/wp-content/uploads/Waveform-LIGO.jpg
Gravitational waves are not phenomena that can be witnessed on a regular basis, they are rather rare events due to many underlying factors discussed in the earlier article/blog- Gravitational waves: Surpassing the limitations of Electromagnetic Radiation. But if it is uncertain then why pay attention to them?
The answer lies in Physics itself, Einstein’s theory predicted Space-time to be a surface that is not absolute and interacts to the influence of matter and energy on it. Gravity waves after 100 years of his prediction are one of the most important experimental proof of his theory. Gravitational waves will help humans discover Cosmological anomalies and even will allow Scientists to understand the very moment after “Big bang”, and who knows maybe something else awaits our future outcome for these detections.
Gravitational waves have a really small magnitude of wavelength as discussed earlier in (Gravitational waves: Surpassing the limitations of Electromagnetic Radiation), but then how are they detected?
If the magnitude is so small how are they detected?
A Physicist from Massachusetts Institute of Technology (MIT) Rainer Weiss, devised a method of detecting Gravity waves, using an interferometer. His mechanism was very simple, it was to shoot a light beam across an isolated tube from its interior and the other end would have a mirror that will reflect back the light beam to its initial source. If a Gravity wave according to the characteristics would distort Space-time, then the light beam will take variable time, this due to the fact that the arms will get stretched and squeezed not even barring light from its influence of “distortions” hence it would even alter light’s wavelength. In other words, the time taken for speed of light to travel to and fro from the mirror before the Gravity wave’s influence would be different from the time taken after the Gravitational wave’s influence on the system.
Image Credit: LIGO, Caltech, MIT, https://www.ligo.caltech.edu/news/ligo20170927
This was an initial idea which further was evolved into a mega structural design named Laser Interferometer Gravitational waves Observatory or “LIGO” for short. LIGO is a machine consisting of two large pipes that extend to about 4 km in length (each). It consists of two mirrors at each end of the two pipes (these mirrors are the world’s most perfectly created mirrors to avoid any shortcomings to the detections), along with a mirror placed at the vertex of the two arms (pipes) at a 450 angle from the laser source. At last, this mechanism consists of a Laser beam rather than any other light beam to maximize accuracy levels.
Working of the machine: Laser Interferometer-
Video Credit: LIGO
Rainer Weiss evolved his concept for detecting Gravitational waves (discussed above), in his new method the light beam from the source would split into two separate light beams (by the mirror placed at this vertex responsible for splitting the single beam into two separate ones) at the vertex of the two arms which hold the mirrors at the end. The two beams then travel through the path to reach the mirrors, then it reflects back and again reunites at the mirror at the vertex of the two arms. The two separated beams will reunite in a way that, other than the splitting point of the beams, the light would not escape anywhere else hence basically canceling each other’s effect.
When a Gravity wave hits the interferometer, it distorts the laser beam and the pipes contracting and expanding them. This will change the amount of time the two separate beams will take to reflect back from the end of the two pipes separately back to the mirror at the vertex of these two arms. Change in time results in escaping a little bit of light due to the failure of canceling each other’s effects. This light then is detected using a device and measuring its intensity will provide the Gravitational wave’s intensity. This method devised by Rainer was absolutely correct and very accurate if successfully implemented to detect Gravity waves to the magnitude of half the size of a vibrating proton.
What are the future prospects of LIGO and Gravitational-wave research?
In 2015, LIGO was successful at detecting Gravitational waves for the first time, in collaboration with another observatory called Virgo. This detection was made for two merging stellar Black holes which were in a Binary system. This provided the first definitive proof for Einstein’s “theory of General Relativity” that Space-time was not absolute and actually curved, one of the biggest milestones to be achieved to solidify the claims of modern physical research. The sound of these “colliding Black holes” is also made available in the public domain by MIT and Caltech so as to provide an interactive data representation of the above complex discovery. After 5 years in 2020, another discovery was made, this discovery was actually was totally unexpected since the mass of the resultant Blackhole after merging of two product Black holes is kind of impossible, the magnitude of its mass is extreme.
Video Credit: MIT & Caltech, Department of Astrophysics
The development of technology and mechanisms over the years in this domain is evident from the above successful detections. But Physicists need to continue to develop the methods of detections, to enhance its performance. Laser Interferometer Space Antenna or “LISA” an idea planned to be executed in the future is improvisation to the current machine LIGO, Gravity waves are very small and the vibrations on Earth (due to people, Earth’s tectonic activities, and other sound polluting phenomena) limits Interferometer’s functioning and hence covers up the important detection of the very low-intensity Gravity waves. To avoid these shortcomings just like a space telescope, a machine with almost the same functioning as LIGO will be placed in space to detect Gravity waves efficiently.
In the future scientists aim at detecting the Gravity waves released just after the “Big bang” to provide its first experimental proof. Not just this many of the experiments and projects are lined up which will bring us closer to understanding the Cosmos and define our existence in this wonderful Universe, or probably a multiverse?