The legendary physicist, Albert Einstein, predicted the existence of gravitational waves years ago. It is no secret that the LIGO team has successfully discovered gravitational waves. Though, Einstein’s discovery of the theory of general relativity is quite well known, what is still not quite widespread that the theory of gravitational waves was also predicted by him.

A paper by Einstein was published in the journal ‘Sitzungsberichte der Königlich-Preussischen Akademie der Wissenschaften zu Berlin’ released by the Prussian Academy in 1916, bearing the title ‘Näherungsweise Integration der Feldgleichungen der Gravitation’ meaning ‘Approximate integration of the field equations of gravity’.

The field equations were Einstein’s equations, which he claimed to solve properly only by considering certain minute deviations from the accurate answers. Taking into consideration certain deviations is quite normal when treating fluctuations. It is understood that the above mentioned fluctuations would eventually come out to be gravitational waves and Einstein would ultimately arrive at them. Across the world this paper is now understood as the introduction of gravitational waves 100 years prior to their actual discovery by the LIGO team.

A distinctive feature of gravitational waves is that they do not possess dipole character, which means that the visible signal happens due to the to and fro movement of charges. In case of gravitational waves, the movement of the radiation is quadrupled, implying that the compression of density happens in one direction and the expansion happens in the orthogonal directions. It is due to this characteristic of the radiation which resulted in the ‘L-form’ of the LIGO interferometers in Hanford, Washington and Livingston, Louisiana.

Einstein realized some mathematical mistakes made in the paper and eventually published another article in 1918, by the name of ‘On Gravitational Waves’. He stated, "But since my exposition of the subject-matter at that time was not sufficiently transparent and furthermore blemished by a regrettable error in calculation, I have to return to the matter here one more time”.