Gravity Waves

Einstein predicted the existence of the gravitational waves in 1915,this theory came to be proven only recently in February 2016 when the LIGO (Laser Interferometer Gravitational-Wave Observatory )detectors in Louisiana ,USA detected a change in length of the tube detector equal to about one-thousandth of the width of a proton, a revolutionary discovery for our times . This phenomenon is based on spacetime. Einstein said that space and time can be merged to form the single continuum of spacetime which can be imagined like a mesh or a net in the universe, the mesh containing the three axes of length, breadth and depth and also the fourth axis of time together forming the spacetime continuum. This mesh is curved by the presence of mass or energy forming a crater in spacetime, greater the mass of the body larger the crater, all other inferior masses tend to fall in this crater, a phenomenon known as gravitation.


Fig. 1 Spacetime


Fig. 2 LIGO

The phenomenon of gravity waves is caused by an event of collision of two masses resulting in ripples in spacetime, described above. This is similar to a pebble being thrown in a pond causing ripples on its surface, the pond here being spacetime and the pebble an event of collision of two masses. The event leading to their discovery in the LIGO was the collision of two blackholes 2.3 billion light-years away. This supergalactic event took place about 2.3 billion years ago and is named GW150914.

The gravitational waves have properties similar to electromagnetic waves i.e. they are transverse waves and travel with the speed of light. They propagate by squeezing and stretching spacetime one after the other. The space at a point being squeezed to such an extent that a uniform meter bar as that made of a Platinum-Iridium alloy at Paris too would witness a bit of lengthening due to the wave but that would be only for an instant and the bar will become normal as soon as the wave passes over.

Gravity waves are caused, as described earlier, when mass or energy collides. This collision can be anything from the collision of two molecules to the collision or formation of neutron stars but the energy levels generated differ. Generally, events such as collision of two cars, breaking of a china cup, explosions etc, do not affect the spacetime mesh strongly and thus no observable changes in the length of matter are caused whereas astrophysical events of large magnitude such as formation of neutron stars or collision of blackholes cause ripples which are large enough in magnitude to cause barely detectable changes in the dimensions of matter. These waves unlike electromagnetic waves have the ability to pierce through all matter of any thickness thus having the capability of reaching places where electromagnetic waves could never have reached.

This recent detection of gravitational waves not only confirms Einstein’s theory which he envisioned about a hundred years before their actual discovery but also open up new realms of understanding the universe. These waves have proved the existence of blackholes (regions of extreme mass and gravity where spacetime is folded upon itself to such an extent that even light cannot escape from being sucked in) which were merely hypothetical till then. This discovery has opened up the possibilities of understanding our universe more widely as their permeability exceeds that of electromagnetic waves thus the objects at great distances in the universe can be ‘seen’ with help of these ripples in spacetime created by them as the electromagnetic spectrum will be absorbed travelling through these huge distances .Some scientists believe that the discovery of gravitational waves will help us to understand the big bang itself. The current effect on our daily lives of this discovery is not so tangible but that was the case when Maxwell predicted the radio waves until Hertz demonstrated them, and even at that time thought that they were not of much use.


Fig. 3 Gravity Waves


[Attribution, especially for the images, which were not created by the author, coming shortly]

One thought on “Gravity Waves

  1. vineeta

    Very Interesting read. I also read that the LIGO Laboratory is working closely with scientists in India at the Inter-University Centre for Astronomy and Astrophysics, the Raja Ramanna Centre for Advanced Technology, and the Institute for Plasma to establish a third Advanced LIGO detector on the Indian subcontinent. What are your thoughts about the same?


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